Answer:
For a: The edge length of the unit cell is 314 pm
For b: The radius of the molybdenum atom is 135.9 pm
Explanation:
For a:To calculate the edge length for given density of metal, we use the equation:
[tex]\rho=\frac{Z\times M}{N_{A}\times a^{3}}[/tex]
where,
[tex]\rho[/tex] = density = [tex]10.28g/cm^3[/tex]
Z = number of atom in unit cell = 2 (BCC)
M = atomic mass of metal (molybdenum) = 95.94 g/mol
[tex]N_{A}[/tex] = Avogadro's number = [tex]6.022\times 10^{23}[/tex]
a = edge length of unit cell =?
Putting values in above equation, we get:
[tex]10.28=\frac{2\times 95.94}{6.022\times 10^{23}\times (a)^3}\\\\a^3=\frac{2\times 95.94}{6.022\times 10^{23}\times 10.28}=3.099\times 10^{-23}\\\\a=\sqrt[3]{3.099\times 10^{-23}}=3.14\times 10^{-8}cm=314pm[/tex]
Conversion factor used: [tex]1cm=10^{10}pm[/tex]
Hence, the edge length of the unit cell is 314 pm
For b:To calculate the edge length, we use the relation between the radius and edge length for BCC lattice:
[tex]R=\frac{\sqrt{3}a}{4}[/tex]
where,
R = radius of the lattice = ?
a = edge length = 314 pm
Putting values in above equation, we get:
[tex]R=\frac{\sqrt{3}\times 314}{4}=135.9pm[/tex]
Hence, the radius of the molybdenum atom is 135.9 pm
What is the maximum number of moles of N-acetyl-p-toluidine can be prepared from 70. milliliters of 0.167 M p-toluidine hydrochloride and an excess of acetic anhydride in an acetate buffer? Enter only the number with two significant figures.
Answer:
[tex]\large \boxed{\text{0.012 mol}}[/tex]
Explanation:
We will need a balanced equation with moles, so let's gather all the information in one place.
CH₃C₆H₄NH₂·HCl + (CH₃CO)₂O ⟶ CH₃C₆H₄NHCOCH₃ + junk
V/mL: 70.
c/mol·L⁻¹: 0.167
For simplicity in writing , let's call p-toluidine hydrochloride A and N-acetyl-p-toluidine B.
The equation is then
A + Ac₂O ⟶ B + junk
1. Moles of A
[tex]\text{Moles of A} = \text{70. mL A}\times \dfrac{\text{0.167 mmol A}}{\text{1 mL A}}= \text{12 mmol A}[/tex]
2. Moles of B
The molar ratio is 1 mol B:1 mol A
Moles of B = moles of A = 12 mmol = 0.012 mol
[tex]\text{You can prepare $\large \boxed{\textbf{0.012 mol}}$ of N-acetyl-p-toluidine. }[/tex]
If a 0.710 m 0.710 m aqueous solution freezes at − 2.00 ∘ C, −2.00 ∘C, what is the van't Hoff factor, i , i, of the solute?
Answer:
The van't Hoff factor of the solute is 1.51
Explanation:
Step 1: Data given
Molality = 0.710 molal
The aqueous solution freezes at − 2.00°C
Freezing point depression constant of water = 1.86 °C/m
Step 2: Calculate the van't Hoff factor
ΔT = i*Kf * m
⇒ with ΔT = The difference between the feezing point of pure and solution = 2.00°C
⇒ i the van't Hoff factor = TO BE DETERMINED
⇒ Kf = Freezing point depression constant of water = 1.86 °C/m
⇒ m = the molality of the solution = 0.710 molal
2.00 = i * 1.86 * 0.710
i = 1.51
The van't Hoff factor of the solute is 1.51
Final answer:
To find the van't Hoff factor for a solution that freezes at − 2.00°C with a molality of 0.710m, the van't Hoff factor, i, is approximately calculated as 1.52, indicating dissociation into multiple particles.
Explanation:
To calculate the van't Hoff factor, i, for the solute in a 0.710 m aqueous solution that freezes at − 2.00 ℃, we use the formula for freezing point depression, ΔTf = iKfm, where ΔTf is the freezing point depression, Kf is the molal freezing-point depression constant for the solvent (water in this case, with a value of − 1.86°C/m), and m is the molality of the solution. First, understand that the freezing point of pure water is 0°C, and the solution's freezing point is − 2.00°C, so the depression, ΔTf, is 2.00°C. To find the van't Hoff factor, i, rearrange the equation to i = ΔTf / (Kfm). Substituting the values gives us i = 2.00 °C / (− 1.86°C/m × 0.710 m) = 2.00°C / − 1.32°C = − 1.52. However, since i should be a positive value and considering the potential rounding or measurement error, the magnitude is taken yielding i approximately equal to 1.52, reflecting the number of particles the solute dissociates into in solution.
A brine solution of salt flows at a constant rate of 77 L/min into a large tank that initially held 100100 L of brine solution in which was dissolved 0.150.15 kg of salt. The solution inside the tank is kept well stirred and flows out of the tank at the same rate. If the concentration of salt in the brine entering the tank is 0.030.03 kg/L, determine the mass of salt in the tank after t min. When will the concentration of salt in the tank reach 0.010.01 kg/L?
Answer:
Explanation: i) Mass per capacity of the tant = (0.15015/100100) kg/L = 0.0000015 kg/L
Amount salt of concentrated salt left = ( 0.03003 - 0.0000015) kg/L = 0.0300285 kg/L
∴ mass of salt in the tank = 0.0300285 kg/L X 77 L/min = 2.31 kg
ii) Capacity of tank at 0.01001 kg/L: 2.31 kg/0.01001 kg/L = 230.77 L
∴ time taken for the concentration of the salt = 230.77/(77 L/min) = 3 minutes.
A solution is prepared by combining 5.00 mL of 4.8x10-4 M NaSCN solution, 2.00 mL of 0.21 M Fe(NO3)3 solution and 13.00 mL of 0.3 M HNO3.
Calculate the analytical concentrations of SCN- and Fe3+ in the resulting solution.
Answer:
The analytical concentrations of thiocyanate ions:
[tex][SCN^-]=0.00012 mol/L[/tex]
The analytical concentrations of ferric ions:
[tex][Fe^{3+}]=0.063 mol/L[/tex]
Explanation:
[tex]Moles (n)=Molarity(M)\times Volume (L)[/tex]
1) Moles of sodium thiocyanate = n
Volume of sodium thiocyanate solution = 5.00 mL = 0.005 L
(1 mL = 0.001L)
Molarity of the sodium thiocyanate = [tex]4.8\times 10^{-4} M[/tex]
[tex]n=4.8\times 10^{-4} M\times 0.005 L=2.4\times 10^{-6}mol[/tex]
1 mole of sodium thiocyanate has 1 mol of thiocyante ions.
So, moles of thioscyanate ions in [tex]2.4\times 10^{-6}mol[/tex] of NaSCN.
[tex]=1\times 2.4\times 10^{-6}mol=2.4\times 10^{-6}mol[/tex]
2) Moles of ferric nitrate = n'
Volume of ferric nitrate solution = 2.00 mL = 0.002 L
Molarity of the ferric nitrate = 0.21 M
[tex]n'=0.002 M\times 0.21 L=0.00042 mol[/tex]
1 mole of ferric nitrate has 3 moles of ferric ions.
So number of moles of ferric ions in 0.00042 moles of ferric nitrate is :
[tex]3\times 0.00042 mol=0.00126 mol[/tex]
Volume of nitric acid = 13.00 mL
Total volume by adding all three volumes of solutions = V
V = 5.00 mL + 2.00 mL + 13.00 mL = 20.00 mL = 0.020 L
The analytical concentrations of thiocyanate ions:
[tex][SCN^-]=\frac{2.4\times 10^{-6}mol}{0.020 L}=0.00012 mol/L[/tex]
The analytical concentrations of ferric ions:
[tex][Fe^{3+}]=\frac{0.00126 mol}{0.020 L}=0.063 mol/L[/tex]
Based on the data provided, the analytical concentrations of SC N⁻ and Fe³⁺ in the solution is 1.2 * 10⁻⁴ M and 2.4 * 10⁻² M.
What is the analytical concentration of SC N⁻ and Fe³⁺ in the solution?The concentration of a solution is calculated using the formula below:
Concentration = moles/volume in Lmoles = molarity * volume in LThe moles of the ions are first determined:
moles of NaSC N⁻ in 5.00 mL in 4.8 * 10⁻⁴ is calculated below:
moles of NaSC N⁻ = 0.005 * 4.8 * 10⁻⁴
moles of NaSC N⁻ = 2.4 * 10⁻⁶ moles
1 mole NaSC N ⁻ produces 1 mole SC N⁻
moles of SC N⁻ = 2.4 * 10⁻⁶ moles
moles of Fe(NO₃)₃ in 2.00 mL in 0.21 M solution is calculated below;
moles of Fe(NO₃)₃ = 0.002 * 0.21
moles of Fe(NO₃)₃ = 4.2 * 10⁻⁴ moles
1 mole Fe(NO₃)₃ produces 1 mole Fe³⁺
moles of Fe³⁺ = 4.2 * 10⁻⁴ moles
Total volume of solution = 0.002 + 0.005 + 0.013
Total volume of solution = 0.020 L
Concentration of SC N⁻ = 2.4 * 10⁻⁶/0.020
Concentration of SC N⁻ = 1.2 * 10⁻⁴ mConcentration of Fe³⁺ = 4.2 * 10⁻⁴/0.02
Concentration of Fe³⁺ = 2.4 * 10⁻² MTherefore, the analytical concentrations of SC N⁻ and Fe³⁺ in the solution is 1.2 * 10⁻⁴ M and 2.4 * 10⁻² M.
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A compound forms between magnesium cation and phosphate anion. Select ALL statements that are TRUE. Group of answer choices The chemical formula of the compound is Mg3(PO4)2. The compound is a covalent compound. The most stable form of a magnesium ion has a charge of 2+ This compound ONLY contains ionic bonds.
Let us label the options in the questions as follows:
Question:
A compound forms between magnesium cation and phosphate anion. Select ALL statements that are TRUE. Group of answer choices
A. The chemical formula of the compound is Mg₃(PO₄)₂.
B. The compound is a covalent compound.
C. The most stable form of a magnesium ion has a charge of 2+
D. This compound ONLY contains ionic bonds.
Answer:
Options A and C
Explanation:
Let us explore all the options,
A. The formula, Mg₃(PO₄)₂, satisfies the charges of both the magnesium (Mg²⁺) and the phosphate ions (PO₄²⁻). Mg²⁺ has three ions, which means the positive charge will be 6 +. The phosphate ions has a negative charge of 3, so two ions of phosphate can counter the six positive charges in the compound. So, the statement is true
B. The compound is not covalent, as Mg²⁺ and PO₄²⁻ ions are bounded by electrostatic forces. So, the statement is false
C. The stable charge of Mg is 2+. Mg is a s block element in the third period. It does not have any empty inner d orbital. Which makes 2+ oxidation state the most stable. So, the statement is true
D. The phosphate group is composed of phosphorous atom covalently bonded to four oxygen atoms. Hence, the compound DOES NOT contain ONLY ionic bonds. So, the given statement is false
The compound forms between magnesium cation and phosphate anion have the chemical formula of the compound is Mg3(PO4)2 and the most stable form of a magnesium ion has a charge of 2+.
The correct options are (A) The chemical formula of the compound is Mg3(PO4)2, (C) The most stable form of a magnesium ion has a charge of 2+.
Magnesium phosphate Magnesium phosphate is a common term for magnesium and phosphate salts that come in a variety of forms and hydrates.It is found in four forms.Thus, the correct options to follow the statements are (A) and (C).
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Electric power is typically given in units of watts (1 W = 1 J/s). About 95% of the power output of an incandescent bulb is converted to heat and 5% to light. If 10% of that light shines on your chemistry text, how many photons per second shine on the book from a 75-W bulb? (Assume the photons have a wavelength of 550 nm.)
To find the number of photons per second that illuminate a book from a 75-W bulb, calculate 5% of the bulb's power for light, take 10% of that for the light on the book, then divide by the energy per photon. The result is approximately 1.04 x 10¹⁸ photons per second.
The student's question is about determining the number of photons per second that shine on a chemistry text from a 75-Watt incandescent bulb, with only 5% of the bulb's power output converting to light and just 10% of that light illuminating the book.
To calculate this, we first determine the total light power output by taking 5% of the bulb's power, which gives us 3.75 Watts (0.05 times 75 W). Next, we need to calculate the power that actually falls on the book, which is 10% of the light power output, or 0.375 Watts. The energy per photon can be calculated using the formula E = (hc)/λ, where 'h' is Planck's constant, 'c' is the speed of light, and 'λ' is the wavelength. For 550 nm (550 x 10-9 meters), the energy per photon is approximately 3.61 x 10⁻¹⁹ Joules. Finally, to find the number of photons per second, we divide the light power on the book by the energy per photon: 0.375 J/s times 1 photon/3.61 x 10⁻¹⁹ J, resulting in approximately 1.04 x 10¹⁸ photons per second.
Calculate the pH at of a 0.10 Msolution of anilinium chloride . Note that aniline is a weak base with a of . Round your answer to decimal place. Clears your work. Undoes your last action. Provides information about entering answers.
The question is incomplete, here is the complete question:
Calculate the pH at of a 0.10 M solution of anilinium chloride [tex](C_6H_5NH_3Cl)[/tex] . Note that aniline [tex](C6H5NH2)[/tex] is a weak base with a [tex]pK_b[/tex] of 4.87. Round your answer to 1 decimal place.
Answer: The pH of the solution is 5.1
Explanation:
Anilinium chloride is the salt formed by the combination of a weak base (aniline) and a strong acid (HCl).
To calculate the pH of the solution, we use the equation:
[tex]pH=7-\frac{1}{2}[pK_b+\log C][/tex]
where,
[tex]pK_b[/tex] = negative logarithm of weak base which is aniline = 4.87
C = concentration of the salt = 0.10 M
Putting values in above equation, we get:
[tex]pH=7-\frac{1}{2}[4.87+\log (0.10)]\\\\pH=5.06=5.1[/tex]
Hence, the pH of the solution is 5.1
The pH of the solution is 5.1.
Calculation of the ph of the solution:Anilinium chloride refers to the salt that should be created by the combination of a weak base (aniline) and a strong acid (HCl).
here the following equation should be used.
ph = 7-1/2(pkb+ logc)
here pkb = negative logarithm of the weak base i.e. aniline = 4.87
And, C = concentration of the salt = 0.10 M
Now the ph should be
= 7-1/2(4.87 + log(0.10))
= 5.1
Hence, The pH of the solution is 5.1.
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A chemistry student needs of -ethyltoluene for an experiment. He has available of a w/w solution of -ethyltoluene in diethyl ether. Calculate the mass of solution the student should use.
For calculating mass of solution, you need to know the concentration of the -ethyltoluene in the solution and the desired amount of -ethyltoluene. Use the mass percentage to calculate the mass of the solution needed.
The question asks for the mass of solution the chemistry student should use to obtain a certain amount of -ethyltoluene for an experiment. To calculate the mass, we need to know the concentration of the -ethyltoluene in the w/w solution and the desired amount of -ethyltoluene.
Let's assume the concentration of the -ethyltoluene in the solution is given as a mass percentage. If the desired mass of -ethyltoluene is known, we can use the mass percentage to calculate the mass of the solution needed.
For example, if the desired mass of -ethyltoluene is 10 grams and the mass percentage of -ethyltoluene in the solution is 5%, then the mass of the solution needed would be:
Mass of solution = 10 grams / (5% / 100%) = 200 grams
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A sample of trifluoroacetic acid, C2HF3O2, contains 26.5 g of oxygen. Calculate the mass of the trifluoroacetic acid sample.
Answer:
94.3 grams
Explanation:
MW of C2HF3O2 is 114g/mol
MW of oxygen in C2HF3O2 is 32g/mol
% composition of oxygen in C2HF3O2 = 32/114 × 100 = 28.1%
Mass of oxygen = 26.5 grams
Mass of trifluoroacetic acid = 26.5/0.281 = 94.3 grams
In the given question, 185.39 g is the mass of the trifluoroacetic acid sample.
Mass is a measure of the amount of matter in an object. The standard metric unit of mass is the kilogram (kg) and grams (gm).
To calculate the mass of the trifluoroacetic acid sample, we need to determine the molar mass of trifluoroacetic acid and then use the given mass of oxygen to find the mass of the entire compound.
The molar mass of trifluoroacetic acid ([tex]\rm C_2HF_3O_2[/tex]) can be calculated by summing the atomic masses of its constituent elements:
Molar mass of [tex]\rm C_2HF_3O_2[/tex] = (2 × 12.01 g/mol) + (1 × 1.01 g/mol) + (3 × 18.99 g/mol) + (2 × 16.00 g/mol)
= 112.03 g/mol
Now, we can use the given mass of oxygen (26.5 g) to find the mass of the entire trifluoroacetic acid sample.
mass (g) = (26.5 g) / (molar mass of O)
mass (g) = (26.5 g) / (16.00 g/mol)
mass (g) = 1.65625 mol
Finally, we can convert moles to grams using the molar mass of trifluoroacetic acid:
mass (g) = 1.65625 mol × 112.03 g/mol
mass (g) = 185.39 g
Therefore, the mass of the trifluoroacetic acid sample is approximately 185.39 g.
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A balloon contains 0.140 molmol of gas and has a volume of 2.78 LL . If an additional 0.152 molmol of gas is added to the balloon (at the same temperature and pressure), what will its final volume be?
Answer:
The final volume will be 5.80 L
Explanation:
Step 1: Data given
Number of moles gas = 0.140 moles
Volume of gas = 2.78 L
Number of moles added = 0.152 moles
Step 2: Calculate the final volume
V1/n1 = V2/n2
⇒ with V1 = the initial volume = 2.78 L
⇒ with n1 = the initial number of moles = 0.140 moles
⇒ with V2 = The new volume = TO BE DETERMINED
⇒ with n2 = the new number of moles = 0.140 + 0.152 = 0.292 moles
2.78/0.140 = V2 /0.292
V2 = 5.80 L
The final volume will be 5.80 L
Based on the balanced chemical equation for the preparation of malachite, what is the composition of the bubbles formed when sodium carbonate is added to the solution of copper sulfate?
Answer:
Carbon Dioxide = CO2
Explanation:
The synthesis of Malachite is seen in the chemical formula:
CuSO 4 . 5H2O(aq) + 2NaCO3(aq) --> CuCO 3 Cu(OH) 2 (s) + 2Na 2 SO 4 (aq) + CO 2 (g) + 9H 2 O(l)
The bubbles mentioned in the question hints that our interest is the compounds in their gseous phase (g).
Upon examining the chemical equation, only CO2 is in the gaseous state and hence the only one that can be formed as bubbles,
The bubbles formed when sodium carbonate is added to the solution of copper sulfate are composed of carbon dioxide (CO2).
Explanation:When sodium carbonate (Na2CO3) is added to a solution of copper sulfate (CuSO4), bubbles of carbon dioxide (CO2) are formed. The balanced chemical equation for this reaction is:
Na2CO3 + CuSO4 → CuCO3 + Na2SO4
So, the composition of the bubbles formed is carbon dioxide (CO2).
Groundwater in Pherric, New Mexico, initially contains 1.800 mg/L of iron as Fe3+. What must the pH be raised to in order to precipitate all but 0.3 mg/L of the iron? The temperature of the solution is 25˚C.
Answer : The pH will be, 3.2
Explanation :
As we known that the value of solubility constant of ferric hydroxide at [tex]25^oC[/tex] is, [tex]2.79\times 10^{-39}[/tex]
Amount or solubility of iron consumed = (1.800 - 0.3) mg/L = 1.5 mg/L
The given solubility of iron convert from mg/L to mol/L.
[tex]1.5mg/L=\frac{1.5\times 10^{-3}g/L}{56g/mol}=2.7\times 10^{-7}mol/L[/tex]
The chemical reaction will be:
[tex]Fe(OH)_3\rightarrow Fe^{3+}+3OH^-[/tex]
The expression of solubility constant will be:
[tex]K_{sp}=[Fe^{3+}]\times [3OH^-]^3[/tex]
Now put all the given values in this expression, we get the concentration of hydroxide ion.
[tex]2.79\times 10^{-39}=(2.7\times 10^{-7})\times [3OH^-]^3[/tex]
[tex][OH^-]=1.5\times 10^{-11}M[/tex]
Now we have to calculate the pOH.
[tex]pOH=-\log [OH^-][/tex]
[tex]pOH=-\log (1.5\times 10^{-11})[/tex]
[tex]pOH=10.8[/tex]
Now we have to calculate the pH.
[tex]pH+pOH=14\\\\pH=14-pOH\\\\pH=14-10.8\\\\pH=3.2[/tex]
Therefore, the pH will be, 3.2
To precipitate all but 0.3 mg/L of iron, the pH must be raised to a certain value. This can be calculated by using the solubility product constant (Ksp) and the balanced equation for the precipitation reaction. By solving for pOH and then pH, we can determine the pH at which the majority of the iron will precipitate.
Explanation:To calculate the pH at which all but 0.3 mg/L of iron will precipitate, we can use the solubility product constant (Ksp) of the iron precipitate. The balanced equation for the precipitation reaction is:
Fe(OH)3(s) ⇌ Fe3+(aq) + 3OH-(aq)
The Ksp expression for this reaction is:
Ksp = [Fe3+][OH-]^3
Assuming that Fe(OH)3 is the only significant source of Fe3+ ions, we can set up an equilibrium expression:
[Fe3+] = Ksp / [OH-]^3
Given that the concentration of Fe3+ ions we want to achieve is 0.3 mg/L, we can substitute this value and solve for the hydroxide ion concentration:
[OH-]^3 = Ksp / [Fe3+]
Since Fe(OH)3 is an amphoteric hydroxide and can behave as both an acid and a base, we can assume that the hydroxide ion concentration is equal to the concentration of the hydroxide ion from water:
[OH-] = 10^(-pOH)
Plugging in the values, we get:
(10^(-pOH))^3 = Ksp / [Fe3+]
Simplifying, we obtain:
10^(-3pOH) = Ksp / [Fe3+]
Taking the logarithm of both sides:
-3pOH = log(Ksp / [Fe3+])
Rearranging the equation and solving for pOH:
pOH = -log(Ksp / [Fe3+]) / 3
To find the pH, we can use the relationship:
pH + pOH = 14
Substituting the pOH value we obtained above:
pH = 14 - pOH
Now we can substitute the given values and calculate the pH at which the majority of iron will precipitate.
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What is the pH of a 1-L solution to which has been added 25 mL of 10 mM acetic acid and 25 mL of 30 mM sodium acetate?
Answer : The pH of the solution is, 5.22
Explanation :
First we have to calculate the moles of acetic acid and sodium acetate.
[tex]\text{Moles of acetic acid}=\text{Concentration of acetic acid}\times \text{Volume of acetic acid}=0.01M\times 0.025L=0.00025mol[/tex]
and,
[tex]\text{Moles of sodium acetate}=\text{Concentration of sodium acetate}\times \text{Volume of sodium acetate}=0.03M\times 0.025L=0.00075mol[/tex]
Now we have to calculate the concentration of acetic acid and sodium acetate in 1 L of solution.
[tex]\text{Concentration of acetic acid}=\frac{\text{Moles of acetic acid}}{\text{Volume of solution}}=\frac{0.00025mol}{1L}=0.00025M[/tex]
and,
[tex]\text{Concentration of sodium acetate}=\frac{\text{Moles of sodium acetate}}{\text{Volume of solution}}=\frac{0.00075mol}{1L}=0.00075M[/tex]
Now we have to calculate the pH of the solution.
Using Henderson Hesselbach equation :
[tex]pH=pK_a+\log \frac{[Salt]}{[Acid]}[/tex]
[tex]pH=pK_a+\log \frac{[\text{Sodium acetate}]}{[\text{Acetic acid}]}[/tex]
[tex]pK_a[/tex] of acetic acid = 4.74
Now put all the given values in this expression, we get:
[tex]pH=4.74+\log (\frac{0.00075}{0.00025})[/tex]
[tex]pH=5.22[/tex]
Thus, the pH of the solution is, 5.22
To find the pH of the solution, calculate the concentration of the acetic acid and sodium acetate. Convert the volume of acetic acid and sodium acetate to liters. Use the Henderson-Hasselbalch equation to find the pH of the buffer solution.
Explanation:To determine the pH of the solution, we need to calculate the concentration of the acetic acid and its conjugate base, sodium acetate. First, convert the volume of acetic acid and sodium acetate to liters. The concentration of acetic acid is 0.01 M (10 mM), and the concentration of sodium acetate is 0.03 M (30 mM). Next, calculate the moles of acetic acid and sodium acetate using the equation moles = concentration x volume. The moles of acetic acid are 0.01 moles, and the moles of sodium acetate are 0.03 moles. The solution contains a weak acid (acetic acid) and its conjugate base (sodium acetate), which makes it a buffer solution. To find the pH of a buffer solution, we need to use the Henderson-Hasselbalch equation: pH = pKa + log ([base]/[acid]). The pKa of acetic acid is 4.74. Substitute the values into the equation: pH = 4.74 + log (0.03/0.01) = 4.74 + log(3) = 4.74 + 0.48 = 5.22. Therefore, the pH of the 1-L solution is 5.22.
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The p K a of the α‑carboxyl group of serine is 2.21 , and the p K a of its α‑amino group is 9.15 . Calculate the average net charge on serine if it is in a solution that has a pH of 8.80 .
Given the pKa values of serine's α‑carboxyl and α‑amino groups, the carboxyl group is fully ionized and carries a -1 charge while the amino group carries a +1 charge at a pH of 8.80. Therefore, the total net charge on serine at this pH is zero.
Explanation:Your question asks to calculate the average net charge on the amino acid serine at a pH of 8.80, given the pKa values for the α‑carboxyl group (2.21) and the α‑amino group (9.15). This is related to the concept of acid dissociation constants (pKa) and buffer solutions in chemistry.
At a pH of 8.80, the pH is higher than the pKa of the α‑carboxyl group but lower than the pKa of the amino group. For the α‑carboxyl group whose pKa is 2.21, the pH is significantly higher. This means, it is fully ionized and carries a -1 charge.
On the other hand, the α‑amino group has a pKa of 9.15, which is higher than the pH of 8.80. This means it is predominantly in its protonated form and carries a +1 charge.
Therefore, the total charge on serine at this pH is the sum of the charges of the α‑carboxyl group and the α‑amino group, which is -1 + 1 = 0. Hence, the average net charge of serine in a solution with pH 8.80 is zero.
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Draw the three structures of the aldehydes with molecular formula C5H10O that contain a branched chain.
Answer:
See picture for answer
Explanation:
First to all, an aldehyde is a carbonated chain with a Carbonile within it chain. It's call aldehyde basically because the C = O is always at the end of the chain. When the C = O is on another position of the chain, is called a ketone.
Now, in this exercise we have an aldehyde with 5 carbons, so the first carbon is the C = O. The remaining four carbon belong to the chain. however, we need to have a branched chain in this molecular formula.
If this the case, this means that the longest chain cannot have 5 carbons. It should have 4 carbons as the longest chain. The remaining carbon, would one branched.
In this case, we only have two possible ways to have an aldehyde with a branched chain, and 4 carbons at max. One methyl in position 2, and the other in position 3.
The remaining aldehyde with branched chain, cannot have 4 carbons as longest, it should have 3 carbons with longest chain and 2 carbons as radicals (In this case, methyl). In this way, we just have all the aldehyde with this formula and at least one branched chain. The other possible ways would be conformers or isomers of the first three.
See picture for the structures of these 3 aldehydes, and their names.}
Consider the following reaction: 2{\rm{ N}}_2 {\rm{O(}}g)\; \rightarrow \;2{\rm{ N}}_2 (g)\; + \;{\rm{O}}_2 (g)
a. In the first 12.0 s of the reaction, 1.7×10−2 mol of {\rm{O}}_2 is produced in a reaction vessel with a volume of 0.240 L. What is the average rate of the reaction over this time interval?
b. Predict the rate of change in the concentration of {\rm{N}}_2 {\rm{O}} over this time interval. In other words, what is {\Delta [{\rm{N}}_2 {\rm{O}}]}/{\Delta t}?
Answer:
a. 5.9 × 10⁻³ M/s
b. 0.012 M/s
Explanation:
Let's consider the following reaction.
2 N₂O(g) → 2 N₂(g) + O₂(g)
a.
Time (t): 12.0 s
Δn(O₂): 1.7 × 10⁻² mol
Volume (V): 0.240 L
We can find the average rate of the reaction over this time interval using the following expression.
r = Δn(O₂) / V × t
r = 1.7 × 10⁻² mol / 0.240 L × 12.0 s
r = 5.9 × 10⁻³ M/s
b. The molar ratio of N₂O to O₂ is 2:1. The rate of change of N₂O is:
5.9 × 10⁻³ mol O₂/L.s × (2 mol N₂O/1 mol O₂) = 0.012 M/s
The ammonia molecule NH3 has a permanent electric dipole moment equal to 1.47 D, where 1 D = 1 debye unit = 3.34 × 10-30 C-m. Calculate the electric potential in volts due to an ammonia molecule at a point 55.3 nm away along the axis of the dipole. (Set V = 0 at infinity.)
The electric potential due to ammonia at a point away along the axis of a dipole is 1.44 [tex]\times[/tex] 10^-5 V.
Explanation:
Given that 1 D = 1 debye unit = 3.34 × 10-30 C-m.
Given p = 1.47 D = 1.47 [tex]\times[/tex] 3.34 [tex]\times[/tex] 10^-30 = 4.90 [tex]\times[/tex] 10^-30.
V = 1 / (4π∈о) [tex]\times[/tex] (p cos(θ)) / (r^2)
where p is a permanent electric dipole,
∈ο is permittivity,
r is the radius from the axis of a dipole,
V is the electric potential.
V = 1 / (4 [tex]\times[/tex] 3.14 [tex]\times[/tex] 8.85 [tex]\times[/tex] 10^-12) [tex]\times[/tex] (4.90 [tex]\times[/tex] 10^-30 [tex]\times[/tex] 1) / (55.3 [tex]\times[/tex] 10^-9)^2
V = 1.44 [tex]\times[/tex] 10^-5 V.
The half-life of bismuth-210, 210Bi, is 5 days.
(a) If a sample has a mass of 216 mg, find the amount remaining after 15 days.
27
Correct: Your answer is correct.
mg
(b) Find the amount remaining after t days.
y(t) =
Incorrect: Your answer is incorrect.
mg
Answer:
(a) Amount remaining after 15 days = 27 mg
(b) Amount remaining after t days = [216(0.5)^t/5] mg
Explanation:
Nt = No(0.5)^t/t1/2
No (initial amount) = 216 mg, t = 15 days, t1/2 (half-life) = 5 days
N15 (amount remaining after 15 days) = 216(0.5)^15/5= 216(0.5)^3 = 216 × 0.125 = 27 mg
(b) Nt (amount remaining after t days) = 216(0.5)^t/5
Answer:
(a). 27 mg, (b). N = 216 (1/2)^ (t/5 days).
Explanation:
From the question, we are given that the half-life of bismuth-210, 210Bi = 5 days, a sample mass = 216 mg, the amount remaining after 15 days= ???(unknown).
Using the equation (1) below we can solve for the amount remaining after 15 days.
N= N° (1/2)^(t/th).-------------------------(1).
Where N = is the amount remaining, N° = is the initial amount, t= is time and th= half life.
Therefore,amount remaining, N = 216mg (1/2)^(15 days/5 days).
=====> Amount remaining, N =216 mg (1/2)^3.
=====> Amount remaining, N= 216 mg × 0.125. = 27 mg.
OR
We can solve it by using; 1/2 M°. Where M° is the initial mass.
Therefore, after 5 days, 1/2 × 216 = 108 mg remains.
After 10 days, 1/2 × 108 mg = 54 mg remains.
After 15 days; 1/2 × 54 mg = 27 mg remains.
(b). We are to find the amount remaining after time, t.
The amount remaining after time,t ==> N= N° (1/2)^(t/th)
===> N = 216 (1/2)^ (t/5 days).
With this we can calculate the amount of the sample at particular time if the time is given.
Compounds A and B were detected in a mixture by TLC. Rf values for both compounds were calculated. Which of the following Rf values would show the smallest separation between compounds? 0.3 and 0.1 0.2 and 0.1 0.8 and 0.6 0.5 and 0.8 none of these choices
Answer:
0.2 and 0.1
Explanation:
Thin Layer Chromatography (TLC) is a type of separation technique which involves a stationary phase (an adsorbent medium) and a mobile phase (a solvent medium), and is used to separate mixtures of non-volatile compounds based on their relative attractions to either phases, which is determined by their polarity.
The more a compound binds to the adsorbent medium, the slower it moves up the TLC plate. Compounds that are polar tend to move up the TLC plate slower than non-polar compounds, resulting in a lower Rf value for polar compounds and a higher Rf value for non-polar compounds.
Rf (Retention factor) = distance moved by compound/solute
distance moved by the solvent front
Rf values of 0.3 and 0.1 gives a difference of 0.2
Rf values of 0.8 and 0.6 gives a difference of 0.2
Rf values of 0.5 and 0.8 gives a difference of 0.3
Rf values of 0.2 and 0.1 gives a difference of 0.1, therefore the smallest separation between compounds is the one with Rf values of 0.2 and 0.1.
Stearic acid (C18H36O2) is a fatty acid, a molecule with a long hydrocarbon chain and an organic acid group (COOH) at the end. It is used to make cosmetics, ointments, soaps, and candles and is found in animal tissue as part of many saturated fats. In fact, when you eat meat, you are ingesting some fats containing stearic acid. Determine the ΔHrxn for this combustion given the following information:
ΔHf of stearic acid = -948 kJ/mol,
ΔHf of CO2 = -394 kJ/mol,
ΔHf of water = -242 kJ/mol.
Calculate the heat (q) released in kJ when 206 g of stearic acid reacts with 943.2 g of oxygen.
Final answer:
The reaction enthalpy (ΔHrxn) for the combustion of stearic acid is -10500 kJ/mol. When 206 grams of stearic acid are combusted, 7602 kJ of heat is released.
Explanation:
Calculating ΔHrxn for the Combustion of Stearic Acid
The combustion reaction for stearic acid (C₁₈H₃₆O₂) can be written as follows:
C₁₈H₃₆O₂(s) + 26O₂(g) → 18CO₂(g) + 18H₂O(l)
To calculate the reaction enthalpy (ΔHrxn), we use the sum of the enthalpies of formation (ΔHf) of the products minus the sum of ΔHf of reactants:
ΔHrxn = [18(ΔHf of CO₂) + 18(ΔHf of H₂O)] - [ΔHf of stearic acid + 26(ΔHf of O₂)]
Since ΔHf for elemental oxygen (O₂) is zero, we simplify the equation to:
ΔHrxn = [18(-394 kJ/mol) + 18(-242 kJ/mol)] - (-948 kJ/mol)
ΔHrxn = (-7092 kJ/mol + -4356 kJ/mol) - (-948 kJ/mol)
ΔHrxn = -11448 kJ/mol + 948 kJ/mol
ΔHrxn = -10500 kJ/mol
To find the heat (q) released when 206 g of stearic acid reacts, we first convert the mass of stearic acid to moles using its molar mass (284.48 g/mol):
Moles of stearic acid = 206 g / 284.48 g/mol = 0.724 mol
Then, multiply the moles by the ΔHrxn:
q = 0.724 mol * -10500 kJ/mol
q = -7602 kJ
Therefore, 7602 kJ of heat is released in the combustion of 206 g of stearic acid.
Draw an orbital diagram showing valence electrons, and write the condensed ground-state electron configuration for each:
(a) Ti (b) Cl (c) V
Answer : The condensed ground-state electron configuration for each is:
(a) [tex][Ar]4s^23d^{2}[/tex]
(b) [tex][Ne]3s^23p^5[/tex]
(c) [tex][Ar]4s^23d^{3}[/tex]
Explanation :
Electronic configuration : It is defined as the representation of electrons around the nucleus of an atom.
Number of electrons in an atom are determined by the electronic configuration.
Noble-Gas notation : It is defined as the representation of electron configuration of an element by using the noble gas directly before the element on the periodic table.
(a) The given element is, Ti (Titanium)
As we know that the titanium element belongs to group 4 and the atomic number is, 22
The ground-state electron configuration of Ti is:
[tex]1s^22s^22p^63s^23p^64s^23d^{2}[/tex]
So, the condensed ground-state electron configuration of Ti in noble gas notation will be:
[tex][Ar]4s^23d^{2}[/tex]
There are 4 number of valence electrons shown in orbital diagram.
(b) The given element is, Cl (Chlorine)
As we know that the chlorine element belongs to group 17 and the atomic number is, 17
The ground-state electron configuration of Cl is:
[tex]1s^22s^22p^63s^23p^5[/tex]
So, the condensed ground-state electron configuration of Cl in noble gas notation will be:
[tex][Ne]3s^23p^5[/tex]
There are 7 number of valence electrons shown in orbital diagram.
(c) The given element is, V (Vanadium)
As we know that the vanadium element belongs to group 5 and the atomic number is, 23
The ground-state electron configuration of Ti is:
[tex]1s^22s^22p^63s^23p^64s^23d^{3}[/tex]
So, the condensed ground-state electron configuration of V in noble gas notation will be:
[tex][Ar]4s^23d^{3}[/tex]
There are 5 number of valence electrons shown in orbital diagram.
To draw valence shell electron configurations and orbital diagrams for Ti, Cl, and V, you place electrons in orbitals according to the electron configuration up to the penultimate shell. Titanium's valence shell configuration is [Ar]3d2 4s2, Chlorine's is [Ne]3s2 3p5, and Vanadium's is [Ar]3d3 4s2.
Explanation:In high school chemistry, understanding electron configurations is fundamental. Here's how you can predict valence shell electron configurations and draw orbital diagrams for titanium (Ti), chlorine (Cl), and vanadium (V).
Titanium (Ti)Titanium has an atomic number of 22. Its electron configuration up to the penultimate shell is [Ar]3d2 4s2. To show the valence electron configuration:
Chlorine has an atomic number of 17. Its electron configuration up to the penultimate shell is [Ne]3s2 3p5. For the valence electrons:
Vanadium has an atomic number of 23. Its electron configuration up to the penultimate shell is [Ar]3d3 4s2. For its valence shell:
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For each of the following sublevels, give the n and l values and the number of orbitals: (a) 5s; (b) 3p; (c) 4f
Answer:
(a) 5s. n = 5. Sublevel s, l = 0. Number of orbitals = 1
(b) 3p. n = 3. Sublevel p, l = 1. Number of orbitals = 3
(c) 4f. n =4. Sublevel f, l = 3. Number of orbitals = 7
Explanation:
The rules for electron quantum numbers are:
1. Shell number, 1 ≤ n
2. Sublevel number, 0 ≤ l ≤ n − 1
So,
(a) 5s. n = 5, shell number 5. Sublevel s, l = 0. Number of orbitals = 2l +1 = 1
(b) 3p. n = 3, shell number 3. Sublevel p, l = 1. Number of orbitals = 2l +1 = 3
(c) 4f. n =4, shell number 4. Sublevel f, l = 3. Number of orbitals = 2l +1 = 7
The 5s sublevel has n=5 and l=0 with 1 orbital, the 3p sublevel has n=3 and l=1 with 3 orbitals, and the 4f sublevel has n=4 and l=3 with 7 orbitals.
Explanation:For the sublevels given, the corresponding quantum numbers and the number of orbitals are as follows:
(a) 5s: The quantum number n is 5 and l is 0, as it is an s sublevel. There is 1 orbital in the s sublevel.(b) 3p: The quantum number n is 3 and l is 1 for the p sublevel. There are 3 orbitals in the p sublevel.(c) 4f: The quantum number n is 4 and l is 3, as it is an f sublevel. There are 7 orbitals in the f sublevel.Learn more about Quantum Numbers and Orbitals here:https://brainly.com/question/41234799
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Write the full ground-state electron configuration for each:
(a) Br (b) Mg (c) Se
Answer:
Bromine (35) 1s²2s²2p63s²3p⁶3d¹⁰ 4s² 4p⁵
Magnesium(12) 1s2 2s2 2p6 3s²
Selenium (34) 1s²2s²2p63s²3p⁶3d¹⁰ 4s² 4p4
Explanation:
In the SPDF electronic configuration, the S orbital can accommodate maximum of 2 electrons,
The P orbital has maximum of 6 electrons
The D orbital has maximum of 10 electrons
The F orbital has maximum of 14 electrons
Bromine with atomic number 35 belongs to group seven(7) period four (4) it ground state electron configuration is 1s²2s²2p63s²3p⁶3d¹⁰ 4s² 4p⁵
Magnesium with atomic number 12 belongs to group one, period two(2), it ground state electron configuration is 1s2 2s2 2p6 3s²
Selenium has atomic number of 34, it belongs to group six(6), period four(4) it electronic configuration is 1s²2s²2p63s²3p⁶3d¹⁰ 4s² 4p4
The ground-state electron configurations for Br (Bromine), Mg (Magnesium), and Se (Selenium) are respectively: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁵ (for Br); 1s² 2s² 2p⁶ 3s² (for Mg); And 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴ (for Se).
Explanation:The ground-state electron configuration refers to the most stable arrangement of electrons around the nucleus of an atom. Here are the ground-state electron configurations for the following atoms:
Br (Bromine): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁵Mg (Magnesium): 1s² 2s² 2p⁶ 3s²Se (Selenium): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴
In each case, the superscript indicates the number of electrons in each energy level. For example, in Br (Bromine), the 1s orbital has 2 electrons, the 2s orbital also has 2 electrons and so on until the 4p orbital which has 5 electrons.
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The compound Xe(CF3)2 decomposes in afirst-order reaction to elemental Xe with a half-life of 30. min.If you place 7.50 mg of Xe(CF3)2 in a flask,how long must you wait until only 0.25 mg ofXe(CF3)2 remains?
Answer:
[tex]t=147.24\ min[/tex]
Explanation:
Given that:
Half life = 30 min
[tex]t_{1/2}=\frac{\ln2}{k}[/tex]
Where, k is rate constant
So,
[tex]k=\frac{\ln2}{t_{1/2}}[/tex]
[tex]k=\frac{\ln2}{30}\ min^{-1}[/tex]
The rate constant, k = 0.0231 min⁻¹
Using integrated rate law for first order kinetics as:
[tex][A_t]=[A_0]e^{-kt}[/tex]
Where,
[tex][A_t][/tex] is the concentration at time t
[tex][A_0][/tex] is the initial concentration
Given that:
The rate constant, k = 0.0231 min⁻¹
Initial concentration [tex][A_0][/tex] = 7.50 mg
Final concentration [tex][A_t][/tex] = 0.25 mg
Time = ?
Applying in the above equation, we get that:-
[tex]0.25=7.50e^{-0.0231\times t}[/tex]
[tex]750e^{-0.0231t}=25[/tex]
[tex]750e^{-0.0231t}=25[/tex]
[tex]x=\frac{\ln \left(30\right)}{0.0231}[/tex]
[tex]t=147.24\ min[/tex]
At 25 °C, only 0.0410 0.0410 mol of the generic salt AB3 is soluble in 1.00 L of water. What is the K sp Ksp of the salt at 25 °C? AB 3 ( s ) − ⇀ ↽ − A 3 + ( aq ) + 3 B − ( aq ) AB3(s)↽−−⇀A3+(aq)+3B−(aq)
Answer: The solubility product of the given salt is [tex]7.63\times 10^{-5}[/tex]
Explanation:
To calculate the molarity of solution, we use the equation:
[tex]\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}[/tex]
Moles of salt = 0.0410 mol
Volume of solution = 1.00 L
Putting values in above equation, we get:
[tex]\text{Molarity of solution}=\frac{0.0410mol}{1.00L}=0.0410M[/tex]
The given chemical equation follows:
[tex]AB_3(s)\rightleftharpoons A^{3+}(aq.)+3B^-(aq.)[/tex]
1 mole of the [tex]AB_3[/tex] salt produces 1 mole of [tex]A^{3+}[/tex] ions and 3 moles of [tex]B^-[/tex] ions
So, concentration of [tex]A^{3+}\text{ ions}=(1\times 0.0410)M=0.0410M[/tex]
Concentration of [tex]B^{-}\text{ ions}=(3\times 0.0410)M=0.123M[/tex]
Expression for the solubility product of will be:
[tex]K_{sp}=[A^{3+}][B^-]^[/tex]
Putting values in above equation, we get:
[tex]K_{sp}=(0.0410)\times (0.123)^3\\\\K_{sp}=7.63\times 10^{-5}[/tex]
Hence, the solubility product of the given salt is [tex]7.63\times 10^{-5}[/tex]
The Ksp of the salt AB₃ at 25°C is 7.63×10^(-7).
To calculate the Ksp (solubility product constant) of the generic salt AB₃ at 25°C, we need to understand the dissolution process and its stoichiometry. The dissolution of AB₃ in water can be represented as:
AB₃ (s) ⇌ A^(3+) (aq) + 3 B^(−) (aq)
Given that 0.0410 mol of AB₃ is soluble in 1.00 L of water, we establish the initial concentrations of the ions in the solution as [A3+] = 0.0410 M and [B−] = 3×0.0410 M = 0.123 M. The Ksp for AB₃ can be calculated using the formula:
Ksp = [A^(3+)][B^(−)]3 = (0.0410)(0.123)³
After calculating, we find that Ksp = 7.63×10^(-7). This value represents the solubility product constant of AB₃ at 25°C, providing insights into its solubility properties under these conditions.
Each of the identical volumetric flasks contains the same solution at two different temperatures. There are two identical volumetric flasks. The first volumetric flask is at 25 degrees Celsius and is filled with a solution to approximately 50% of the neck of the flask. The second volumetric flask is at 55 degrees Celsius and is filled with a solution to approximately 80% of the neck of the flask. What changes for the solution with temperature?
Explanation:
We know that molarity is the number of moles of solute present in liter of solution.
Mathematically, Molarity = [tex]\frac{\text{no. of moles}}{\text{volume in liter}}[/tex]
As molarity is dependent on volume and volume of a solution or substance is dependent on temperature. So, with increase in temperature there will occur a decrease in volume of the solution. As a result, molarity will increase as it is inversely proportional to volume.
Hence, molarity of both the solutions will be different as temperature of both the solutions is different.
In order to obtain changes for the solution with temperature we need to get the molarity for both the solutions.
What is Molarity?It is the concentration of a solution measured as the number of moles of solute per liter of solution.
It is given by:
[tex]\text{Molarity} = \frac{\text{Number of moles}}{\text{volume}}[/tex]
Molarity depends inversely on volume.So, with increase in temperature there will occur a decrease in volume of the solution. Thus, molarity will increase when volume gets decreased.Hence, Molarity of both the solutions will be different as temperature of both the solutions is different.
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Water (3110 g ) is heated until it just begins to boil. If the water absorbs 5.19×105 J of heat in the process, what was the initial temperature of the water that this will require a total of 3600 kcal of energy for the trip. For her food supply, she decides to take nutrition bars. The label states that each bar contains 50 g of carbohydrates, 10 g of fat, and 40 g of protein.
Answer:
The question requires the value of the initial temperature which is found to be 60.266 °C ≅ 60.3 °C
Explanation:
To solve this question we list out the given variables as follows
Mass of water = 3110 g
Heat energy absorbed = 5.19 × 10⁵ J
Heat Energy required to raise the temperature of water to boiling point =
ΔH = m×C×Δθ where
m = mass of waster = 3110 g = 3.11 kg
C = specific heat capacity of water = 4.2 J/g°C
Δθ = Temperature change = T₂ - T₁ and
T₂ = 100°C which is the normal boiling point temperature of water
Hence 5.19 ×10⁵ J = 3110 g × 4.2 J/g°C ×Δθ
from where Δθ = (5.19 ×10⁵ J)/(13062 J/°C) = 39.73 °C
But Δθ = T₂ - T₁ = 100 °C- T₁ = 39.73 °C then
T₁ = -100 °C - 39.73 °C = 60.266 °C
Hence the initial temperature of the water is 60.266 °C
Final answer:
The initial temperature of the water can be calculated using the specific heat of water (4.184 J/g °C) and the amount of heat absorbed (5.19×10^5 J) before boiling.
Explanation:
The specific heat of water is a critical concept in thermodynamics and is essential for solving problems involving temperature changes. To calculate the initial temperature of the water, we utilize the specific heat capacity, which for water is 4.184 J/g °C. The amount of heat required to raise the temperature of a given mass of water is determined by this specific heat capacity.
For instance, using the information provided, if water absorbs 5.19×105 J of heat, we can set up an equation to find the initial temperature (Tinitial) before it began to boil. Using the formula q = mcΔT, where 'q' is the heat absorbed, 'm' is the mass, 'c' is the specific heat capacity, and 'ΔT' is the change in temperature, we find:
5.19×105 J = (3110 g)(4.184 J/g°C)(100°C - Tinitial)
This equation can be solved for Tinitial to find the initial temperature of the water.
To aid in the prevention of tooth decay, it is recommended that drinking water contain 1.10 ppm fluoride, F−. How many grams of F− must be added to a cylindrical water reservoir having a diameter of 4.30 × 102 m and a depth of 56.03 m?
Answer: The mass of fluoride ions that must be added will be [tex]8.943\times 10^6g[/tex]
Explanation:
The equation used to calculate the volume of cylinder is:
[tex]V=\pi r^2h[/tex]
where,
r = radius of the reservoir= [tex]\frac{d}{2}=\frac{4.30\times 10^2m}{2}=215m[/tex]
h = height of the reservoir = 56.03 m
Putting values in above equation, we get:
[tex]\text{Volume of reservoir}=(3.14)\times (215)^2\times 56.03\\\\\text{Volume of reservoir}=8.13\times 10^6m^3[/tex]
Converting this into liters, we use the conversion factor:[tex]1m^3=1000L[/tex]
So, [tex]8.13\times 10^6m^3=8.13\times 10^9L[/tex]
Mass of water reservoir = [tex]8.13\times 10^9kg[/tex] (Density of water = 1 kg/L )
We are given:
Concentration of fluoride ion in the drinking water = 1.10 ppm
This means that 1.10 mg of fluoride ion is present in 1 kg of drinking water
Calculating the mass of fluoride ion in given amount water reservoir, we use unitary method:
In 1 kg of drinking water, the amount of fluoride ion present is 1.10 mg
So, in [tex]8.13\times 10^9kg[/tex] of drinking water, the amount of fluoride ion present will be = [tex]\frac{1.10mg}{1kg}\times 8.13\times 10^9kg=8.943\times 10^9mg[/tex]
Converting this into grams, we use the conversion factor:1 g = 1000 mg
So, [tex]8.943\times 10^9mg\times \frac{1g}{1000mg}=8.943\times 10^6g[/tex]
Hence, the mass of fluoride ions that must be added will be [tex]8.943\times 10^6g[/tex]
Final answer:
To achieve a fluoride concentration of 1.10 ppm in a cylindrical water reservoir with a 430 meter diameter and a 56.03 meter depth, 90.035 grams of fluoride ion (F−) must be added.
Explanation:
To calculate the amount of F− needed to attain a concentration of 1.10 ppm in a cylindrical water reservoir, let's first determine the volume of the reservoir. The volume (V) of a cylinder is given by the formula V = πr²h, where r is the radius (half the diameter) and h is the height (or depth in this case). Given a diameter of 4.30 × 10² m and a depth of 56.03 m, the radius r = 2.15 × 10² m.
So, the volume V = π(2.15 × 10² m)²(56.03 m) = π(4.6225 × 10´ m²)(56.03 m) = 8.185 × 10· m³. To convert this volume to liters (since ppm is mg/L), recall that 1 m³ = 1,000 L, making the reservoir's volume 8.185 × 10· m³ × 1,000 = 8.185 × 10±0 L.
With a target fluoride concentration of 1.10 ppm (− or mg/L), the mass (m) of F− required is:
m = concentration × volume = 1.10 mg/L × 8.185 × 10±0 L = 90,035 mg, or 90.035 g.
Thus, to achieve a fluoride concentration of 1.10 ppm in the water reservoir, 90.035 grams of F− must be added.
A mixture of sand (SiO2), sodium chloride (NaCl), and iron (Fe) filings had a mass of 30.126 g. After analysis this mixture was found to contain 15.976 g of sand and 3.455 g of iron. What is the mass percent (%) of sodium chloride in the sample?
Answer:
35.5 % NaCl
Explanation:
Total mass of mixture = 30.126 g
Mass of sand = 15.976 g
Mass of iron = 3.455 g
Mass of NaCl = ? → Total mass - 15.976 g - 3.455 g = 10.695 g
% mass of NaCl in the sample → (Mass of NaCl / Total mass) . 100
(10.695 g / 30.126 g) . 100 = 35.5 %
Arrange each set in order of increasing atomic size:
(a) Rb, K, Cs (b) C, O, Be (c) Cl, K, S (d) Mg, K, Ca
Answer:
Part A:
Order: K<Rb<Cs
Part B:
Order: O<C<Be
Part C:
Order:CL<S<K
Part D:
Order:Mg<Ca<K
Explanation:
Atomic Size:
It is the distance from the center to atom to the valance shell electron. It is very difficult to measure the atomic size because there is definite boundary of atom.
Trend:
Moving from top to bottom in a group, Atomic Size increases.
Moving from left to right in a period, Atomic size generally decreases.
On the basis of above trend we will solve our question:
Part A:
All elements belong to Group 1:
Moving from top to bottom in a group, Atomic Size increases.
Order: K<Rb<Cs
Part B:
All elements belong to 2nd Period:
Moving from left to right in a period, Atomic size generally decreases.
Order: O<C<Be
Part C:
S belongs to 3rd Period, K, Cl belong to 4th period
Order:CL<S<K
Part D:
Mg is above Ca in group 2 and K is before Ca in 4th period
From trends described above:
Order:Mg<Ca<K
Final answer:
Each set is arranged in order of increasing atomic size, reflecting the trend that atomic size increases down a group and decreases across a period.
Explanation:
Arranging each set in order of increasing atomic size based on their positions in the periodic table:
(a) K, Rb, Cs
(b) Be, C, O
(c) Cl, S, K
(d) Mg, Ca, K
Atomic size typically increases from top to bottom within a group and decreases from left to right across a period. So in each set, the element located further down a group will be larger, and the element on the farther left of a period will be smaller.