Which example shows a chemical change?

A evaporating water

B. melting ice

C. rust

D cutting pap​

Answer:

-1.9 KJ/mol

Explanation:

In order to solve the problem, we have to rearrange the equations in a way in which all molecules of O₂ and CO₂ are eliminated:

2C(diamond) + 2O₂(g) → 2CO₂(g)     ΔH₁= 2 x (-395.4 KJ) ------> we multiply by 2 both reactants and products

2 CO₂(g) → 2CO(g) + O₂(g)         ΔH₂= 566.0 KJ

CO₂(g) → C(graphite) + O₂(g)     ΔH₃= -1 x (-393.5 KJ) ------> we use reverse rxn

2CO(g) → C(graphite) + CO₂(g)   ΔH₄= -172.5 KJ

When we cancel the molecules that appear both in reactants and products, the total reaction is the following:

2C(diamond) → 2C(graphite)

ΔHt= ΔH₁ + ΔH₂ + ΔH₃ + ΔH₄ = 2 x (-395.4 KJ) + 566.0 KJ + (-1 x (-393.5 KJ)) - 172.5 KJ

ΔHt= 347.2 KJ

This is for 2 mol of C(diamond) which are converted in 2 mol of C(graphite). To obtain ΔH for the reaction of 1 mol C(diamond) to 1 mol (graphite) we have to divide into 2:

ΔH= -3.8 KJ/2mol= -1.9 KJ/mol

To determine ΔHrxn for the reaction C(diamond) → C(graphite), we can use Hess's law and the given equations. By canceling out common compounds/products and summing the remaining equations, we can calculate ΔHrxn. The enthalpy change can be determined by summing the enthalpy changes of the canceled equations.

This type of calculation usually involves the use of Hess's law, which states: If a process can be written as the sum of several stepwise processes, the enthalpy change of the total process equals the sum of the enthalpy changes of the various steps. For this specific reaction, we can use the given equations to determine the enthalpy change ΔHrxn for C(diamond) → C(graphite).

To obtain the ΔHrxn for C(diamond) → C(graphite), we need to cancel out common compounds/products in these equations. From the given equations, we can see that CO2(g) is a common compound in steps 1, 2, and 3, and thus we can cancel it out. Likewise, O2(g) is present in steps 1, 2, and 3, so we can also cancel it out. By summing the canceled equations, we get the final equation:

C(diamond) → C(graphite)

The enthalpy change for this reaction is the sum of the enthalpy changes of the canceled equations:

ΔHrxn = ΔH1 + ΔH2 + ΔH3 + ΔH4 = -395.4 kJ + 566.0 kJ + (-393.5 kJ) + (-172.5 kJ) = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + (-393.5 kJ) + 566.0 kJ + (-172.5 kJ) = -395.4 kJ - 393.5 kJ + 566.0 kJ - 172.5 kJ = -395.4 kJ - 393.5 kJ + 566.0 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ = -395.4 kJ + 566.0 kJ - 393.5 kJ - 172.5 kJ

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Answer : The concentration of the NaOH solution is, 0.738 M

Explanation :

To calculate the concentration of base, we use the equation given by neutralization reaction:

[tex]n_1M_1V_1=n_2M_2V_2[/tex]

where,

[tex]n_1,M_1\text{ and }V_1[/tex] are the n-factor, molarity and volume of acid which is [tex]H_2SO_4[/tex]

[tex]n_2,M_2\text{ and }V_2[/tex] are the n-factor, molarity and volume of base which is NaOH.

We are given:

[tex]n_1=2\\M_1=0.300M\\V_1=24.6mL\\n_2=1\\M_2=?\\V_2=20.0mL[/tex]

Putting values in above equation, we get:

[tex]2\times 0.300M\times 24.6mL=1\times M_2\times 20.0mL[/tex]

[tex]M_2=0.738M[/tex]

Thus, the concentration of the NaOH solution is, 0.738 M

Answer:

Photosystems PSI (P700) and PSII (P680) and photolysis of water releases energy

In the form of movement of electrons which is later extracted as ATP

Explanation:

On absorbing light energy electrons obtained from photolysis of water and those present in and those present in the reaction centres PSI and PSII move to the higher energy level and electron acceptors accept them. They then move down through the electron transport chain to the lower energy level during which ATP is produced which is a chemical form of energy.

Answer:

The following must be true for diffusion of a solute to occur across a partition that separates two compartments

The partition is semi permeable

There is  concentration gradient across the partition

The process is known as Osmosis

Explanation:

Diffusion is the migration of particles of a substance, liquid or gas, from a region of high concentration to a region of lower concentration and it only occurs where there is a concentration gradient for example spraying a perfume at a corner of a room, the spray sent spreads across the room as there is a concentration gradient

Osmosis is the movement or diffusion of solvent molecules across a semi permeable membrane from a region of low solute concentration to a region of high solute concentration to create a balanced concentration of solute on both sides of the compartment.

Diffusion requires a concentration gradient and a membrane permeable to the solute; in osmosis, water diffuses to balance solute concentrations.

For the diffusion of a solute to occur across a partition that separates two compartments, there must be a concentration gradient present, where the solute molecules move from an area of higher concentration to an area of lower concentration. Additionally, permeability of the membrane to the solute is crucial, as only materials capable of passing through will diffuse.

In certain situations, such as osmosis, water will move across the membrane to balance the concentration gradient of solutes, when the solutes themselves cannot pass through the membrane. In living systems, osmosis is a dynamic and continuous process that maintains the balance of fluids.

Answer:

Option (4)

Explanation:

The primitive atmosphere was comprised of lesser or no amount of oxygen. With the progressive time, primitive organisms appeared such as the primitive aquatic plants, algae, and cyanobacteria, that carried out the process of photosynthesis in the presence of sunlight, water, and CO₂, and in return produced the food and oxygen. This is how the rapid photosynthesis process led to the increasing amount of oxygen in the atmosphere that facilitates the growth and evolution of different life forms on earth.

Thus, the correct answer is option (4).

Answer:

The answer to your question is None of your answers is correct, maybe the data are wrong.

Explanation:

Data

Concentration 1 = C1 = 1 M

Volume 2 = 5 ml

Concentration 2 = 0.05 M

Volume 1 = x

To solve this problem use the dilution formula

             Concentration 1 x Volume 1 = Concentration 2 x Volume 2

Solve for Volume 1

              Volume 1 = (Concentration 2 x Volume 2)/ Concentration 1

Substitution

              Volume 1 = (0.05 x 5) / 1

Simplification

              Volume 1 = 0.25/1

Result

               Volume 1 = 0.25 ml

Answer:

[tex]\rho=7.15\ g/cm^3[/tex]

Explanation:

The expression for density is:

[tex]\rho=\frac {Z\times M}{N_a\times {{(Edge\ length)}^3}}[/tex]

[tex]N_a=6.023\times 10^{23}\ {mol}^{-1}[/tex]

M is molar mass of Chromium = 51.9961 g/mol

For body-centered cubic unit cell , Z= 2

[tex]\rho[/tex] is the density  

Radius = 125 pm = [tex]1.25\times 10^{-8}\ cm[/tex]

Also, for BCC, [tex]Edge\ length=\frac{4}{\sqrt{3}}\times radius=\frac{4}{\sqrt{3}}\times 1.25\times 10^{-8}\ cm=2.89\times 10^{-8}\ cm[/tex]

Thus,  

[tex]\rho=\frac{2\times \:51.9961}{6.023\times \:10^{23}\times \left(2.89\times 10^{-8}\right)^3}\ g/cm^3[/tex]

[tex]\rho=7.15\ g/cm^3[/tex]

The density of solid crystalline chromium will be "7.15 g/cm³".

According to the question,

Radius,

Molar mass of Chromium,

For body-centered,

For BCC,

The edge length will be:

= [tex]\frac{4}{\sqrt{3} }\times radius[/tex]

= [tex]\frac{4}{\sqrt{3} }\times 1.25\times 10^{-8}[/tex]

= [tex]2.89\times 10^{-8} \ cm[/tex]

hence

The expression for density will be:

→  [tex]\rho = \frac{Z\times M}{N_a(Edge \ length)^3}[/tex]

By substituting the values, we get

      [tex]= \frac{2\times 51.9961}{6.023\times 10^{23}\times (2.89\times 10^{-8})}[/tex]

      [tex]= 7.15 \ g/cm^3[/tex]

Thus the above approach is right.

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Answer:

a) C₈H₁₈ + (23/2)O₂ -----> 8CO₂ + 9H₂O

b) Mass of CO₂ produced annually from this combustion of isooctane gasoline = 1.12 × 10⁵ Kg

c) CO₂ produced from the combustion of the gasoline in a year will occupy 5.632 × 10⁷ L

d) There needs to be a minimum of 1.752 × 10⁷ moles of air and 3.92 × 10⁸ L of air for the oxygen to be in excess all through the year of gasoline combustion.

Explanation:

a) C₈H₁₈ + (23/2)O₂ -----> 8CO₂ + 9H₂O

b) C₈H₁₈ has a density of 0.792 mg/L.

Since density = mass/volume;

mass = density × volume

Mass of C₈H₁₈ with 4.6 x 10^10 L volume = 0.792 × 4.6 x 10^10 = 3.643 × 10^10 mg = 3.643 × 10⁷ g.

To obtain the mass of CO₂ produced, we need the number of moles of C₈H₁₈ that burned.

Number of moles = mass/molar mass

Molar mass of C₈H₁₈ = (8×12) + 18 = 114g/mol

Number of moles of C₈H₁₈ = (3.643 × 10⁷)/114 = (3.2 × 10⁵) moles.

From the chemical reaction,

1 mole of C₈H₁₈ burns to give 8 moles of CO₂

(3.2 × 10⁵) moles will give 8 × 3.2 × 10⁵ = (2.56 × 10⁶) moles of CO₂

Mass of CO₂ produced = number of moles × Molar mass

Molar mass of CO₂ = 44 g/mol

Mass of CO₂ produced = 2.56 × 10⁶ × 44 = 1.12 × 10⁸ g = 1.12 × 10⁵ kg

c) 1 mole of any gas at stp occupies 22.4L

2.56 × 10⁶ moles of CO₂ will occupy 2.56 × 10⁶ × 22.4 = 5.632 × 10⁷ L

d) 1 mole of C₈H₁₈ requires 23/2 moles of O₂ for complete combustion yearly.

3.2 × 10⁵ moles would require 3.2 × 10⁵ × 23/2 = 3.68 × 10⁶ moles of O₂

O₂ makes up 21% of the air

That is,

0.21 moles of O₂ would be contained in 1 mole of air

3.68 × 10⁶ moles of O₂ would be contained in (3.68 × 10⁶ × 1)/0.21 = 1.752 × 10⁷ moles of air.

1 mole of any gas at stp occupies 22.4L

1.752 × 10⁷ of air will occupy

1.752 × 10⁷ × 22.4/1 = 3.92 × 10⁸ L of air!

Final answer:

The balanced equation for the combustion of isooctane is C8H18(l) + 11O2(g) → 8CO2(g) + 9H2O(g). Assuming that gasoline is 100% isooctane, the mass of CO2 produced each year by the annual US gasoline consumption of 4.6 x 10^10 L is 9.04 x 10^6 kg. The volume of this CO2 at STP is 2.03 x 10^11 L. We use the molar ratios from the balanced equation to determine the number of moles of air necessary for the combustion of 1 mol of isooctane. The volume in L of this air at STP is 1173 L.

Explanation:

The balanced chemical equation for the combustion of isooctane (C8H18) is:

C8H18(l) + 11O2(g) → 8CO2(g) + 9H2O(g)

Assuming that gasoline is 100% isooctane, we can use the balanced equation to calculate the mass of CO2 produced each year by the annual US gasoline consumption of 4.6 x 1010 L. We start by calculating the mass of isooctane consumed, then use the molar ratios from the balanced equation to calculate the mass of CO2 produced. Given that the density of isooctane is 0.792 g/mL, the mass consumed is 4.6 x 1010 L x 0.792 g/mL = 3.64 x 1010 g. The molar mass of CO2 is 44.01 g/mol, so the number of moles of CO2 produced is 28 x 3.64 x 1010 g / 114.22 g/mol = 9.04 x 109 mol. Finally, we convert to kilograms by dividing by 1000, so the CO2 produced is 9.04 x 106 kg.

To calculate the volume of CO2 at STP, we use the ideal gas law. At STP (Standard Temperature and Pressure), 1 mole of gas occupies 22.4 L. So, the volume of CO2 at STP is 9.04 x 109 mol x 22.4 L/mol = 2.03 x 1011 L.

We use the molar ratios from the balanced equation to determine the number of moles of air necessary for the combustion of 1 mol of isooctane. From the equation, we can see that 11 moles of O2 are required for the combustion of 1 mol of isooctane. Since air is 21.0% O2 by volume, the volume of air required is 11 / 0.21 = 52.4 mol. At STP, 1 mole of gas occupies 22.4 L, so the volume of air required is 52.4 mol x 22.4 L/mol = 1173 L.

Answer:

Option a.

0.01 mol of CaCl₂ will have the greatest effect on the colligative properties, because it has the biggest i

Explanation:

To determine which of the solute is going to have a greatest effect on colligative properties we have to consider the Van't Hoff factor (i)

These are the colligative properties:

ΔP = P° . Xm . i  →  Lowering vapor pressure

ΔT = Kb . m . i  → Boiling point elevation

ΔT = Kf . m . i  →  Freezing point depression

π = M . R . T  →  Osmotic pressure

Van't Hoff factor are the numbers of ions dissolved in the solution. For nonelectrolytes, the i values 1.

CaCl₂ and KNO₃ are two ionic solutes. They dissociate as this:

CaCl₂  → Ca²⁺ + 2Cl⁻

We have 1 mol of Ca²⁺ and 2 chlorides, so 3 moles of ions → i = 3

KNO₃ → K⁺ + NO₃⁻

We have 1 mol of K⁺ and 1 mol of nitrate, so 2 moles of ions → i = 2

Option a, is the best.

0.01 mol of CaCl2 has the greatest effect on colligative properties because it dissociates into three ions per formula unit, resulting in a higher number of dissolved particles compared to the same amount of KNO3, which dissociates into two ions, and CO(NH2)2, which does not dissociate.

The solute that has the greatest effect on the colligative properties for a given mass of pure water from the options provided would be 0.01 mol of CaCl2 (an electrolyte). This is because the colligative properties such as freezing point depression, boiling point elevation, and osmotic pressure depend on the total number of dissolved particles in solution.

When CaCl2 dissolves in water, it dissociates into three ions: one Ca2+ ion and two Cl- ions. This means for every mole of CaCl2 we get three moles of particles. In contrast, 0.01 mol of KNO3, another electrolyte, produces two ions per formula unit, and 0.01 mol of CO(NH2)2 (urea, a nonelectrolyte) does not dissociate into ions when dissolved, hence producing only one mole of particles per mole of solute.

Therefore, for the given mass of 0.01 mol, CaCl2 produces the greatest number of particles and therefore has the greatest effect on colligative properties when compared to KNO3 and urea.

Answer:

The terms used to describe the given process in Chemical weathering.

Explanation:

Weathering of rock is defined as breaking down of the rock into small pieces.

There are two types pf weathering :

Mechanical weathering : This weathering is due to change in physical parameters : temperature change, pressure change etc.

For example : When water soaked up in cracks or crevices of rocks freezes it expands and physically breaks the rock.

Chemical weathering : This weathering is decomposition of rocks due to action of chemicals.This type of weathering also changes chemical composition of rocks.

For example : when gases like carbon dioxide, sulfur oxide get dissolves in water present in rock to form weak acid which ease up the dissolving of rock in that weak acid.

Answer:

The corrext answer is E. make; break

Explanation:

In living organisms, the metabolism is either anabolic or catabolic where anabolic metabolism is energy consuming and catabolic metabolism is eneegy releasesing. It should however be noted that anabolic reaction builds or biosynthesize new mollecular structures while catabolic reaction breaks down complex structure bonds into simple structures

The braking down of bonds in catabolic reations realeses energy to sustain the anabolic rection process for the formation of new bonds

Anabolic reactions create or 'make' new bonds while forming complex structures, requiring energy. Catabolic reactions involve 'break' down bonds to create simpler structures, often releasing energy.

The correct answer is E. Anabolic reactions are those that 'make' or form new bonds, they involve the joining of smaller molecules to form larger, more complex ones. This process often requires energy. Conversely, catabolic reactions are those that 'break' or degrade bonds, they involve the breaking down of larger molecules into smaller, simpler ones. This process often releases energy.

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The gas laws involve Charles' Law, showing a direct proportionality between volume and temperature for a gas. The new volume of the gas after being cooled from 20°C to -60°C (converted to Kelvin), which is under constant pressure, is calculated to be approximately 30.6 mL.

This question involves the concept of the gas laws in Physics, specifically, Charles' Law which states that the volume of a given mass of an ideal gas is directly proportional to its temperature on an absolute scale if pressure and the amount of gas remain constant.

First, let's convert the Celsius temperatures to Kelvin by adding 273.15. This gives us initial temperature T1 = 20°C + 273.15 = 293.15 K and final temperature T2 = -60°C + 273.15 = 213.15 K. The initial volume V1 is 42 mL.

According to Charles' Law, V1/T1 = V2/T2. Substituting the given values, we find the new volume V2 = V1*(T2/T1) = 42 mL * (213.15 K / 293.15 K) = 30.6 mL.

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Answer: that one

Explanation:

Answer:

Unstable Nuclei. ... Too many neutrons or protons upset this balance disrupting the binding energy from the strong nuclear forces making the nucleus unstable. An unstable nucleus tries to achieve a balanced state by given off a neutron or proton and this is done via radioactive decay.

Explanation:

Answer:FeS

Explanation:

Mass of sulphur=5.95-3.78=2.17g

Fe S

3.78/56. 2.17/32

0.0675/0.0675. 0.0678/0.0675

1:1

Empirical formula=Fe1S1=FeS

An empirical formula is a compound's chemical formula that only specifies the ratios of the elements it contains and not the precise number or arrangement of atoms. The empirical formula is FeS.

The formula of a material expressed with the smallest integer subscript is referred to as an empirical formula for a compound. The empirical formula provides details regarding the ratio of atom counts in the molecule. A compound's empirical formula is directly related to its % content.

Mass of sulphur = 5.95 - 3.78 = 2.17g

Moles of Fe and S are:

Fe = 3.78/56

n = 0.0675

S = 2.17/32

n = 0.0678

Dividing with the smallest number:

0.0675/0.0675 = 1

0.0678/0.0675 = 11

The ratio is:

1:1

Empirical formula = FeS

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Answer:

Option B.

Explanation:

Let's replace the data given in the formula of Ideal Gases Law.

P. V = n . R . T

3L . 1000kPa = n . 8.31 L.kPa/mol.K . 298K

(3L . 1000 kPa) / ( 8.31 L.kPa/mol.K . 298K) = n

1.21 moles

The number of moles of oxygen by using ideal gas equation is 1.21 moles. Hence, the correct option is B.

[tex]PV=nRT[/tex]

Here, P is the pressure, V is the volume, n is the number of moles, R is the gas constant, T is the temperature.

We can calculate the number of moles by using the above equation as follows:-

[tex]PV = n R T\\ 1000kPa\times 3L = n \times 8.31 L.kPa/mol.K \times298K\\(3L . 1000 kPa) / ( 8.31 L.kPa/mol.K . 298K) = n\\n=1.21 moles[/tex]

So, the number of moles of oxygen is 1.21 moles.

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Answer:

The sun is the large astronomical body that is located at the center of the solar system. The interior structure of the sun are as follows-

Answer:

Vital

Explanation:

Hello! The factors mentioned previously are essential substances for the life and health of our bodies. Not only in humans, but also for animals. They are factors that are linked and contribute to physical and mental energy, growth and life. Are essentials because humans can't live without that.

Thanks for your question! Feel free to ask more!

Average C-H bond energy: Ethane = 764.93 kJ/mol, Ethene = 627.79 kJ/mol, Ethyne = 528.26 kJ/mol.

To find the average C-H bond energy in ethane (C₂H₆), ethene (C₂H₄), and ethyne (C₂H₂), we can use Hess's law and the given reactions along with the average C-H bond energy in methane (CH₄), which is 415 kJ/mol.

1. **Calculate the average C-H bond energy in ethane (C₂H₆):**

  Given reaction:

[tex]\[C2H6 (g) + H2 (g) \rightarrow 2CH4 (g) \quad \Delta H_{\text{rxn}} = -65.07 \, \text{kJ/mol}\][/tex]

  This reaction breaks one C-C bond and adds two C-H bonds.

  Change in bond energy = Total energy of bonds broken - Total energy of bonds formed

[tex]\[= 1 \times (\text{C-C bond energy}) - 2 \times (\text{C-H bond energy})\][/tex]

  From the given reaction, the change in bond energy is -65.07 kJ/mol.

  Substituting the known values:

 [tex]\[-65.07 \, \text{kJ/mol} = 1 \times (\text{C-C bond energy}) - 2 \times (415 \, \text{kJ/mol})\][/tex]

  Solving for the C-C bond energy:

[tex]\[\text{C-C bond energy} = 2 \times 415 - 65.07 \, \text{kJ/mol} = 764.93 \, \text{kJ/mol}\][/tex]

2. **Calculate the average C-H bond energy in ethene (C₂H₄):**

  Given reaction:

[tex]\[C2H4 (g) + H2 (g) \rightarrow 2CH4 (g) \quad \Delta H = -202.21 \, \text{kJ/mol}\][/tex]

  This reaction breaks one C=C bond and adds two C-H bonds.

  Change in bond energy = Total energy of bonds broken - Total energy of bonds formed

[tex]\[= 1 \times (\text{C=C bond energy}) - 2 \times (\text{C-H bond energy})\][/tex]

  From the given reaction, the change in bond energy is -202.21 kJ/mol.

  Substituting the known values:

[tex]\[-202.21 \, \text{kJ/mol} = 1 \times (\text{C=C bond energy}) - 2 \times (415 \, \text{kJ/mol})\][/tex]

  Solving for the C=C bond energy:

 [tex]\[\text{C=C bond energy} = 2 \times 415 - 202.21 \, \text{kJ/mol} = 627.79 \, \text{kJ/mol}\][/tex]

3. **Calculate the average C-H bond energy in ethyne (C₂H₂):**

  Given reaction:

  [tex]\[C2H2 (g) + 3H2 (g) \rightarrow 2CH4 (g) \quad \Delta H = -376.74 \, \text{kJ/mol}\][/tex]

  This reaction breaks one C≡C bond and adds four C-H bonds.

  Change in bond energy = Total energy of bonds broken - Total energy of bonds formed

[tex]\[= 1 \times (\text{C≡C bond energy}) - 4 \times (\text{C-H bond energy})\][/tex]

  From the given reaction, the change in bond energy is -376.74 kJ/mol.

  Substituting the known values:

[tex]\[-376.74 \, \text{kJ/mol} = 1 \times (\text{C≡C bond energy}) - 4 \times (415 \, \text{kJ/mol})\][/tex]

  Solving for the C≡C bond energy:

 [tex]\[\text{C = C bond energy} = 4 \times 415 - 376.74 \, \text{kJ/mol} = 528.26 \, \text{kJ/mol}\][/tex]

So, the average C-H bond energy in ethane [tex](C2H6) is \(764.93 \, \text{kJ/mol}\), in ethene (C2H4) is \(627.79 \, \text{kJ/mol}\), and in ethyne (C2H2) is \(528.26 \, \text{kJ/mol}\).[/tex]

Answer:

The metallic bond of the sodium metal is weaker than the ionic bond of the sodium chloride

Explanation:

The metallic bond of the sodium metal is weaker than the ionic bond of the sodium chloride. This is seen in the fact that the melting point of the sodium metal which is 97.8°C is lower than the melting point of the sodium chloride which is 801°C. This shows that the inter-atomic bonds of the sodium metal are weaker than that of the inter-ionic bonds of the sodium chloride which will require higher energy to break which is shown by its high melting point of 801°C. The melting point of the sodium metal of 97.8 °C which is lower requires less energy to break its bonds. This is shown by its lower melting point.

Answer:

C. Running bond

Explanation:

The common bond is a structural bonding pattern for bricks with a single wythe.

The structural bonding pattern for bricks that features a single wythe is the common bond.

Answer:

Archaebacteria belong to the kingdom 'Archaea'. They resemble bacteria when observed under a microscope.They are single-cell organisms. However,they differ from prokaryotes in many ways.

•They have a completely different cell membrane so that they can survive and thrive in harsh environments

•Unlike bacteria,their cell wall and membrane can be stiff and gives a specific shape such as flat,rod shaped or cubic.

•the absence of peptidoglycan in cell wall,instead contain lipid and protein to give them strength and resistance against chemical.

•The cell membrane of archae are made up of phospholipid bilayer but unlike bacteria and eukaryotes,the bilayers have ether bonds.These ether bonds have the ability to resist chemical and helps them to survive in very extreme environments that might otherwise kill them.

•They have multiple RNA polymerase that contain multiple polypeptide

•They have initiator tRNA with unmodified methionine(unlike bacteria).

•They have the ability to survive in very high temperatures,in acidic environment and alkaline environments and even have tolerance for high salt content.

Equation of reaction

NaHCO3 +  HCl  --------->  NaCl  +  H2O  +  CO2(g)

1)The mass(actual yield) of CO2 can be gotten by isolating it from other products and getting its mass.

Assume 1.0g of CO2 was gotten as a product of the experiment

2) For the theoretical yield

The mass of NaHCO3 was not stated, but for the purpose of this solution, I would assume 2g of NaHCO3 was used for the experiment. You can substitute any parameter by following the steps I follow

Number of mole of NaHCO3 = Mass of NaHCO3/ Molar Mass of NaHCO3

Number of mole of NaHCO3 = 2/84.01 = 0.0238 moles

1 mole of NaHCO3 yielded 1 mole of CO2

0.0238 moles of NaHCO3 will yield 0.0238 moles of CO2

Mass of CO2 = Number of moles * Molar Mass

Mass of CO2 = 0.0238 * 44 = 1.0472g

Theoretical yield of CO2 = 1.0472 grams

3) Percentage yield of CO2 = Actual yield/Theoretical yield *100%

Percentage yield of CO2 = 1.0/1.0472 *100

Percentage yield of CO2 = 95.49%

Answer:

1) The mass of [tex]CO_{2}[/tex] produced is 1.29g

2) The theoretical yield for [tex]CO_{2}[/tex] is 1.311g

3) The percent yield is 98.4%

Explanation:

Step 1: in an experiment let's allow sodium bicarbonate (baking soda) to react with hydrochloric acid HCl to obtain high yield [tex]CO_{2}[/tex].

[tex]NaHCO_{3}+HCl[/tex] ⇒ [tex]NaCl + H_{2} O + CO_{2}[/tex]

from the balanced equation it can be seen that 1 mole of [tex]NaHCO_{3[/tex] produces 1 mole of [tex]CO_{2}[/tex].

Step 2: Let assume 2.5g of [tex]NaHCO_{3[/tex] were used

mole of [tex]NaHCO_{3[/tex] = 2.5g/molecular mass of [tex]NaHCO_{3[/tex]

molecular mass of[tex]NaHCO_{3[/tex] = 23+1+12+(16×2) = 84g/mol

converting mass of [tex]NaHCO_{3[/tex] into mole we have:

           [tex]\frac{2.5g}{84gmol^{-1} }[/tex]= 0.0298 moles

Step 3: since [tex]NaHCO_{3[/tex] : [tex]CO_{2}[/tex] mole is ratio 1:1, then 0.0298 mole of [tex]NaHCO_{3[/tex] will produce 0.0298 mole of [tex]CO_{2}[/tex]

The mass of this amount of [tex]CO_{2}[/tex] = 0.0298 × molecular mass of [tex]CO_{2}[/tex]

                = 0.0298 mol × ( 12+(16×2))g/mol = 1.3111g of [tex]CO_{2}[/tex]

 therefore; the theoretical yield expected is 1.311g

Step 4: Let assume for the experiment that we obtained 1.29g  of [tex]CO_{2}[/tex] as the actual yield

then, percent yield for [tex]CO_{2}[/tex] = [tex]\frac{Actual yield obtained}{theoretical yield that should have been obtained}[/tex] × 100%

                                             = 1.2g/1.311g × 100% =98.4%

Answer:62.66°C or 235.66K

Explanation:Q=McpT, the energy was given in calories so you first convert to Joules by multiplying the value in calories by 4.184J.

17*4.184=71.128kJ.

71.128kJ=mcpT

71.128kJ=245*4.187*(T-Tm)

Tm is the final temperature of the mixture. The T is the temperature given which should be converted to Kelvin by adding 273...T=32+273=305K.

71128J=245*4.187*(305-Tm)

71128=312873.575-1025.815Tm

1025.815Tm=312873.575-71128

1025.815Tm=241745.58

Tm=241745.58/1025.815

Tm=235.66K

Answer:

0.1976 atm is the total pressure in the container at equilibrium.

Explanation:

The value of [tex]K_p[/tex] for the given reaction = 0.842

Partial pressure of the hydrogen sulfide = 0.104 atm

Partial pressure of the hydrogen sulfide at equilibrium = (0.104-x) atm

Partial pressure of the hydrogen gas at equilibrium = x

Partial pressure of the sulfur gas at equilibrium = x

[tex]H_2S(g)\rightleftharpoons 2H_2(g)+S(g)[/tex]

Initially

0.104 atm                      0  0

At equilibrium

(0.104 -2x)                      2x   x

The expression of  [tex]K_p[/tex] is given by ;

[tex]K_p=\frac{x\times x}{(0.104 -x) }[/tex]

[tex]0.842 =\frac{x^2}{(0.104-x)}[/tex]

Solving for x:

x = 0.0936 atm

Partial pressure of the hydrogen sulfide at equilibrium = (0.104-x) atm

= (0.104-0.0936 ) atm = 0.0104 atm

Partial pressure of the hydrogen gas at equilibrium = x = 0.0936 atm

Partial pressure of the sulfur gas at equilibrium = x = 0.0936 atm

Total pressure in the container will be sum of all the partial pressure of the hydrogen sulfide gas, hydrogen gas and sulfur gas at the equilibrium.

P = 0.0104 atm + 0.0936 atm + 0.0936 atm = 0.1683 atm

0.1976 atm is the total pressure in the container at equilibrium.

The total pressure in the system at equilibrium is calculated using the equilibrium constant Kp and the initial pressure of the system. By setting up a equilibrium constant expression and solving the quadratic equation for 'x', the change in pressure, we find that the total pressure at equilibrium in the system is ~0.101 atm.

The decomposition reaction of H2S into H2 and S is a chemical equilibrium problem in which the equilibrium constant is given in terms of pressure, or Kp. We know that at the beginning, only H2S is present at a pressure of 0.104 atm, and at equilibrium, the pressure of H2S decreases by 'x', being 'x' the pressure of H2 and S at equilibrium. According to the expression of the equilibrium constant Kp, Kp = (pH2* pS) / p_H2S = x^2 / (0.104-x).

From here, if we solve for 'x' using the quadratic formula and the given Kp = 0.842, we find two solutions, ~0.0967 atm and ~0.0072 atm. We discard the result 0.0967 because it cannot be higher than the initial pressure of the system, so the correct 'x' is ~0.0072 atm. Therefore, the total pressure will be the sum of the individual pressures at equilibrium. Total Pressure = pH2 + pS + p_H2S = 2x + (0.104-x) = 2*0.0072 + (0.104-0.0072) = ~0.101 atm.

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Answer:

130 g of O₂

Explanation:

Let's apply the Ideal Gases Law, to solve this.

Pressure . volume = moles . R . T° (K)

First of all, we need to convert the volume in mL to L, because the units of R

10000 mL . 1L/1000mL = 10L

Let's replace → 10 atm . 10L = n . 0.082L.atm/mol.K . 300K

(100 atm.L) / (0.082L.atm/mol.K . 300K) = n

4.06 moles = n

Let's convert the moles to mass → 4.06 mol . 32 g/1mol = 130 g

Answer:

a. Molecular formula of phenylalanine → C₉H₁₁NO₂

b. 234.2 g of C₉H₁₁NO₂

Explanation:

Let's think the reaction:

C₁₄H₁₈N₂O₅  +  2H₂O →  CH₃OH  +  ‎C₉H₁₁NO₂ + C₄H₇NO₄

In order to work with this reaction, we assume that water is on excess.

Let's determine the moles of aspartame → molar mass = 294 g/mol

Moles = mass / molar mass → 378 g / 294 g/mol = 1.28 moles

As ratio is 1:1, 1 mol of aspartame can produce 1 mol of phenylalanine; therefore 1.28 moles of aspartame must produce 1.28 moles of phenylalanine.

Let's convert the moles to mass → molar mass C₉H₁₁NO₂ = 183 g/mol

Moles . molar mass = Mass → 1.28 mol . 183 g/mol = 234.2 g

A. The molecular formula of phenylalanine is C₉H₁₁NO₂

B. The mass of phenylalanine, C₉H₁₁NO₂ produced from 378 g of aspartame is 212.14 g

A. Determination of the molecular formula of phenylalanine.

To obtain the molecular formula of phenylalanine, we shall write the balanced equation. This is given below

C₁₄H₁₈N₂O₅ + 2H₂O → C₄H₇NO₄ + CH₃OH + C₉H₁₁NO₂

Thus, the molecular formula of phenylalanine is C₉H₁₁NO₂

B. Determination of the mass of phenylalanine, C₉H₁₁NO₂ produced from 378 g of aspartame

C₁₄H₁₈N₂O₅ + 2H₂O → C₄H₇NO₄ + CH₃OH + C₉H₁₁NO₂

Molar mass of C₁₄H₁₈N₂O₅ = (14×12) + (18×1) + (14×2) + (16×5) = 294 g/mol

Mass of C₁₄H₁₈N₂O₅ from the balanced equation = 1 × 294 = 294 g

Molar mass of C₉H₁₁NO₂ = (9×12) + (11×1) + 14 + (16×2) = 165 g/mol

Mass of C₉H₁₁NO₂ from the balanced equation = 1 × 165 = 165 g

From the balanced equation above,

294 g of C₁₄H₁₈N₂O₅ reacted to produce 165 g of C₉H₁₁NO₂

Therefore,

378 g of C₁₄H₁₈N₂O₅ will react to produce = (378 × 165) / 294 = 212.14 g of C₉H₁₁NO₂

Thus, 212.14 g of C₉H₁₁NO₂ were obtained from the reaction.

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Answer: 0.75 moles of Phosphorus and 4.5 moles of Hydrogen are produced respectively from 3 moles of Phosporus.

Explanation:

4PH3 --------> P4 + 6H2

From the stochiometry of the reaction,

4 moles of Phosphine gives 1 mole of Phosphorus

3 moles of Phosphine will give (3×1)/4 moles of Phosphorus.

Therefore, 0.75 moles of Phosphorus is produced.

Similarly, 4 moles of Phosphine gives 6 moles of Hydrogen

3 moles of Phosphine will give (3×6)/4 moles of Hydrogen.

Therefore, 4.5 moles of Hydrogen is produced.

QED!

Answer:

Full disk encryption

Explanation:

Disk encryption is a protection technique used in securing information by converting it into unreadable codes that cannot decrypt in other to prevent unauthorized persons from accessing the information.

When cryptography is applied to entire disks, it is termed Full disk encryption.

The volume change during Iron's BCC to FCC transformation is computed via cubing the atomic radii and applying them to a percent change formula. The increasing radius hints at a likely volume increase, however, the exact percent change requires numerical calculation.

To answer your question on whether the volume increases or decreases during the allotropic transformation of Iron (Fe) from a BCC phase (with atomic radius rBCC = 0.12584 nm) to an FCC phase (rFCC = 0.12894 nm), we need to recognize that the volume of an atom in a crystal structure can be determined by cubing its atomic radius, and the volume change can be obtained by taking the difference between the initial and final volumes.

The initial volume (of the BCC phase) is (0.12584 nm)³, while the final volume (of the FCC phase) is (0.12894 nm)³. The percent volume change can then be computed by [(final volume - initial volume)/initial volume] x 100%.

If this calculation yields a positive value, this would mean the volume increases; if the result is a negative value, the volume decreases. While it's evident that the radius increases during this transformation, due to the cubic relationship between radius and volume, it's likely that the volume also increases, although the actual percent volume change would require numerical computation.

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Final answer:

The percent volume change during the allotropic transformation of iron from BCC to FCC can be calculated using the given atomic radii and results in an increase in volume.

Explanation:

To compute the percent volume change associated with the allotropic transformation of iron (Fe) from a BCC (body-centered cubic) structure to an FCC (face-centered cubic) structure at 912°C, we can use their respective atomic radii and the equation for the volume of a sphere, V = (4/3)πr3. Given the atomic radii for BCC as rBCC = 0.12584 nm and for FCC as rFCC = 0.12894 nm, the respective volumes can be calculated.

After obtaining the volumes, we calculate the percent volume change with the formula: Volume Change (%) = (VFCC - VBCC)/VBCC x 100%. Using the given radii, we find that the volume of FCC iron is larger than BCC iron, indicating that the volume increases during the transformation. The actual numerical percent volume change can be computed using the given radii values and the volume equation stated above.

Answer: The molar composition of nitrogen gas is 0.6 and that of oxygen gas is 0.4

Explanation:

To calculate the molarity of solution, we use the equation:

[tex]\text{Molarity of the solution}=\frac{\text{Mass of solute}}{\text{Molar mass of solute}\times \text{Volume of solution (in L)}}[/tex]

Given mass of nitrogen gas = 51.3 mg = 0.0513 g     (Conversion factor:  1 g = 1000 mg)

Molar mass of nitrogen gas = 28 g/mol

Volume of solution = 2 L

Putting values in above equation, we get:

[tex]\text{Molarity of nitrogen gas}=\frac{0.0513g}{28g/mol\times 2L}\\\\\text{Molarity of nitrogen gas}=9.16\times 10^{-4}mol/L[/tex]

To calculate the partial pressure, we use the equation given by Henry's law, which is:

[tex]C_{N_2}=K_H\times p_{N_2}[/tex]

where,

[tex]K_H[/tex] = Henry's constant = [tex]6.1\times 10^{-4}mol/L.atm[/tex]

[tex]C_{N_2}[/tex] = molar solubility of nitrogen gas = [tex]9.16\times 10^{-4}mol/L[/tex]

Putting values in above equation, we get:

[tex]9.16\times 10^{-4}mol/L=6.1\times 10^{-4}mol/L.atm\times p_{N_2}\\\\p_{N_2}=\frac{9.16\times 10^{-4}mol/L}{6.1\times 10^{-4}mol/L.atm}=1.50atm[/tex]

We are given:

Total pressure of the mixture = 2.50 atm

Partial pressure of oxygen gas = 2.50 - 1.50 = 1.00 atm

To calculate the mole fraction of a substance at 25°C, we use the equation given by Raoult's law, which is:

[tex]p_{A}=p_T\times \chi_{A}[/tex]       ......(1)

where,

[tex]p_A[/tex] = partial pressure

[tex]p_T[/tex] = total pressure

[tex]\chi_A[/tex] = mole fraction

We are given:

[tex]p_{N_2}=1.50atm\\p_T=2.50atm[/tex]

Putting values in equation 1, we get:

[tex]1.50atm=2.50\times \chi_{N_2}\\\\\chi_{N_2}=\frac{1.50}{2.50}=0.6[/tex]

We are given:

[tex]p_{O_2}=1.00atm\\p_T=2.50atm[/tex]

Putting values in equation 1, we get:

[tex]1.00atm=2.50\times \chi_{O_2}\\\\\chi_{O_2}=\frac{1.00}{2.50}=0.4[/tex]

Hence, the molar composition of nitrogen gas is 0.6 and that of oxygen gas is 0.4

The mole fraction of nitrogen and oxygen is 0.6 and 0.4 respectively.

Data Given;

The law states that the mass of a dissolved gas in a given volume of solvent at equilibrium will be proportional to the partial pressure of the gas.

Mathematically;

C = KP

The number of moles Nitrogen dissolved is

[tex]n = mass/ molar mass\\ n = 0.0513/28\\ n = 0.00183127 moles[/tex]

The concentration of Nitrogen in water is

[tex]\frac{0.00183127}{2} *1 = 0.0009156M[/tex]

Applying Henry's law,

[tex]0.0009156 = 6.1*10^-^4 * P\\ P = 1.5atm[/tex]

The partial pressure of nitrogen in the mixture is 1.5atm

The total pressure of the gas is 2.50atm

Partial Pressure of oxygen = total pressure - partial pressure of nitrogen

partial pressure of oxygen = 2.50 - 1.50 = 1

The pressure fraction of the gas is the ratio between the partial pressure to the total pressure

pressure fraction of nitrogen = 1.5/2.5 = 0.6

pressure fraction of oxygen = 1/2.5 = 0.4

But partial pressure is equal to molar fraction.

This makes the mole fraction of nitrogen equals 0.6 and mole fraction of oxygen equals 0.4.

Learn more about Henry's law here;

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