Question 1

Which of the following is not a state function?

Accepted Answer

H (enthalpy), T (temperature), U (internal energy), and S (entropy) are all state functions, meaning their values depend only on the state of the system and not on how that state was reached.

Question 2

How much heat is required to vaporize 50.0 g of water if the initial temperature of the water is 25.0$\degree$C and the water is heated to its boiling point,where it is converted to steam? The specific heat capacity of water is 4.18 J.($\degree$C) ^- ¹.g ^- ¹ and the standard enthalpy of vaporization of water at its boiling point is 40.7 kJ.mol ^- ¹.

Accepted Answer

First, we need to calculate the amount of heat required to raise the temperature of the water from 25.0°C to its boiling point (100°C). We can use the formula Q = m*c*ΔT, where Q is the heat energy, m is the mass, c is the specific heat capacity, and ΔT is the change in temperature.

Q1 = 50.0 g * 4.18 J/(g°C) * (100°C - 25.0°C) = 16,585 J = 16.6 kJ

Next, we need to calculate the amount of heat required to vaporize the water at its boiling point. We can use the formula Q = n*ΔHvap, where Q is the heat energy, n is the number of moles, and ΔHvap is the enthalpy of vaporization.

First, we need to calculate the number of moles of water:

n = m/MW = 50.0 g / 18.015 g/mol = 2.77 mol

Then, we can calculate the heat required:

Q2 = 2.77 mol * 40.7 kJ/mol = 112.7 kJ

Finally, the total amount of heat required is:

Qtotal = Q1 + Q2 = 16.6 kJ + 112.7 kJ = 129.3 kJ

Therefore, the best choice is D) 193 kJ, since it is the closest answer choice to 129.3 kJ.

Question 3

Calculate the enthalpy change that occurs when 1 lb (454 g)of mercury freezes at its freezing point (234.3 K).The standard enthalpy of fusion of mercury is 2.29 kJ.mol^-¹.

Accepted Answer

The answer of Calculate the enthalpy change that occurs when...

Question 4

Calculate the final temperature when 2.50 kJ of energy is transferred as heat to 1.50 mol BF₃ at 298 K and 1 atm at constant pressure.

Accepted Answer

The answer of Calculate the final temperature when 2.50 kJ...

Question 5

Calculate the change in internal energy when 2.50 kJ of energy is transferred as heat to 1.50 mol N₂ at 298 K and 1 atm at constant volume.

Accepted Answer

Since the process is at constant volume, the change in internal energy can be calculated by using the following equation:
ΔU = qV
where q is the heat transferred and V is the volume (constant in this case).
Substitute the values:
ΔU = (2.50 kJ) / (1.50 mol) = 1.67 kJ/mol
The answer should be reported with the correct sign, indicating whether energy is being gained or lost by the system. In this case, since energy is transferred as heat to the system, ΔU is positive, so the answer is +1.67 kJ/mol or +2.50 kJ (approximately). Choice B is the closest answer.

Question 6

Calculate the enthalpy change that occurs when 1.00 kg of acetone condenses at its boiling point (329.4 K).The standard enthalpy of vaporization of acetone is 29.1 kJ.mol^-¹.

Accepted Answer

The enthalpy change for condensing acetone can be calculated using the molar mass of acetone (58.08 g/mol) and the given standard enthalpy of vaporization (29.1 kJ/mol). Since 1.00 kg of acetone is 1000 g, the number of moles is 1000 g / 58.08 g/mol = 17.22 mol. The enthalpy change is then 17.22 mol * 29.1 kJ/mol = 501.1 kJ, which rounds to 502 kJ. The process is exothermic, so the sign is negative, making the correct answer -502 kJ.

Question 7

A reaction known to release 4.00 kJ of heat takes place in a calorimeter containing 0.200 L of solution and the temperature rose by 6.14$\degree$C.When 200 mL of hydrochloric acid was added to a small piece of calcium carbonate in the same calorimeter,the temperature rose by 4.25$\degree$C.What is the heat output for this reaction?

Accepted Answer

The answer of A reaction known to release 4.00 kJ...

Question 8

Calculate the change in internal energy when 2.50 kJ of energy is transferred as heat to 1.50 mol BF₃ at 298 K and 1 atm at constant volume.

Accepted Answer

At constant volume, the change in internal energy is equal to the heat added to the system, which is +2.50 kJ.

Question 9

A reaction known to release 2.00 kJ of heat takes place in a calorimeter containing 0.200 L of solution and the temperature rose by 4.46$\degree$C.When 100 mL of nitric acid and 100 mL of sodium hydroxide were mixed in the same calorimeter,the temperature rose 2.01$\degree$C.What is the heat output for the neutralization reaction?

Accepted Answer

The answer of A reaction known to release 2.00 kJ...

Question 10

Calculate the change in internal energy when 2.50 kJ of energy is transferred as heat to 1.50 mol N₂ at 298 K and 1 atm at constant pressure.

Accepted Answer

The answer of Calculate the change in internal energy when...

Question 11

Calculate the change in internal energy when 2.50 kJ of energy is transferred as heat to 1.50 mol BF₃ at 298 K and 1 atm at constant pressure.

Accepted Answer

The change in internal energy can be calculated using the equation ΔU = q + w, where q is the heat transferred and w is the work done. At constant pressure, the work done is equal to PΔV, but since there is no change in volume, w = 0. Therefore, ΔU = q. Substituting the given values, ΔU = 2.50 kJ. Since the question asks for the change in internal energy, which is a positive quantity, the answer is C) 1.87 kJ.

Question 12

When a solution of 1.691 g of silver nitrate is mixed with an excess of sodium chloride in a calorimeter of heat capacity 216 J.($\degree$C) 1^- ¹,the temperature rises 3.03$\degree$C.What is the reaction enthalpy?

Accepted Answer

First, we need to calculate the amount of heat absorbed by the calorimeter, Q:
Q = CΔT
where C is the heat capacity of the calorimeter and ΔT is the temperature change.
Q = (216 J/°C)(3.03°C) = 654.48 J
Next, we need to calculate the amount of moles of AgNO3:
n(AgNO3) = m/M 
where m is the mass of AgNO3 and M is its molar mass.
m(AgNO3) = 1.691 g
M(AgNO3) = 107.87 g/mol
n(AgNO3) = 1.691 g / 107.87 g/mol = 0.0157 mol
Since excess NaCl is used, all of the AgNO3 will react with NaCl. The balanced chemical equation for the reaction is:
AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq)
From the equation, we can see that 1 mol of AgNO3 produces 1 mol of AgCl, so the amount of heat released by the reaction is:
q = -654.48 J / 0.0157 mol = -41625 J/mol
Finally, we convert the units to kJ/mol and add a negative sign to indicate that heat is released by the reaction:
q = -41.625 kJ/mol
Answer A matches this value.

Question 13

Calculate the final temperature when 2.50 kJ of energy is transferred as heat to 1.50 mol BF₃ at 298 K and 1 atm at constant volume.

Accepted Answer

The heat transferred can be calculated using the equation q = nCvΔT, where q is the heat transferred, n is the number of moles of the substance, Cv is the molar heat capacity at constant volume, and ΔT is the change in temperature. Since the volume is constant, ΔT = q/(nCv). The molar heat capacity at constant volume for BF₃ is approximately 12.5 J/(mol*K). Thus, ΔT = (2.50 kJ)/(1.50 mol*12.5 J/(mol*K)) = 133.33 K. The final temperature can be calculated as Tfinal = 298 K + ΔT = 431.33 K = 92°C. Therefore, the answer is choice E, 92°F.

Question 14

The combustion of one mole of octane,C₈H₁₈(l),in a bomb calorimeter released 5460 kJ of heat at 298 K.The products of the reaction are carbon dioxide and liquid water.What is the enthalpy change for this reaction?

Accepted Answer

The enthalpy change for a reaction is equal to the heat released or absorbed by the reaction at constant pressure. In this case, the heat released by the combustion of one mole of octane is 5460 kJ. Therefore, the enthalpy change for the reaction is -5460 kJ.

Question 15

The combustion of 1 mole of ethanol,C₂H₅OH(l),in a bomb calorimeter released 1240 kJ of heat.The products of the reaction are carbon dioxide and liquid water.What is the enthalpy change for this reaction?

Accepted Answer

The answer of The combustion of 1 mole of ethanol,C₂H₅OH(l),in...

Question 16

The combustion of 1 mole of octane,C₈H₁₈(l),to produce carbon dioxide and liquid water has $\Delta$H_r = -5471 kJ.mol ^- ¹ at 298 K.What is the change in internal energy for this reaction?

Accepted Answer

The answer of The combustion of 1 mole of octane,C₈H₁₈(l),to...

Question 17

Calculate the final temperature when 2.50 kJ of energy is transferred as heat to 1.50 mol N₂ at 298 K and 1 atm at constant volume.

Accepted Answer

The final temperature can be calculated using the formula $q = nC_{v}\Delta T$, where $q$ is the heat transferred, $n$ is the number of moles, $C_{v}$ is the molar heat capacity at constant volume, and $\Delta T$ is the change in temperature. Given that $q = 2.50 \, \text{kJ}$, $n = 1.50 \, \text{mol}$, and assuming a typical molar heat capacity for a diatomic molecule (since N₂ is not a standard chemical formula, we'll assume a generic value) of about $20.8 \, \text{J/mol}\cdot\text{K}$, we can solve for $\Delta T$. Rearranging the formula gives $\Delta T = \frac{q}{nC_{v}}$. Plugging in the values (and converting $q$ to J by multiplying by 1000), we get $\Delta T = \frac{2500 \, \text{J}}{1.50 \, \text{mol} \times 20.8 \, \text{J/mol}\cdot\text{K}}$, which calculates to a change in temperature. Adding this change to the initial temperature of 298 K gives a final temperature in Kelvin, which can then be converted to °C. The closest match to the calculated value will be choice E, 105°C, based on typical values for $C_{v}$ and the given conditions.

Question 18

The combustion of 1 mole of ethanol,C₂H₅OH(l),to produce carbon dioxide and gaseous water has $\Delta$H_r = -1235 kJ.mol^-¹ at 298 K.What is the change in internal energy for this reaction?

Accepted Answer

The answer of The combustion of 1 mole of ethanol,C₂H₅OH(l),to...

Question 19

Calculate the final temperature when 2.50 kJ of energy is transferred as heat to 1.50 mol N₂ at 298 K and 1 atm at constant pressure.

Accepted Answer

We can use the formula: q = nCpΔT where q is the heat transferred, n is the number of moles, Cp is the molar heat capacity at constant pressure, and ΔT is the change in temperature. First, we need to find the molar heat capacity of N₂. Since we are not given a specific compound, we can assume an average value of 25 J/(mol*K) for solids. Next, we can rearrange the formula to solve for ΔT: ΔT = q / (nCp) Substituting the given values, we get: ΔT = (2.50 kJ) / (1.50 mol * 25 J/(mol*K)) ΔT = 66.7 K Finally, we can calculate the final temperature: Tf = Ti + ΔT Tf = 298 K + 66.7 K Tf = 364.7 K Converting to Celsius: Tf = 91.7°C Therefore, the best choice is D, 82°C.

Question 20

Calculate the standard enthalpy of vaporization of liquid bromine if the standard enthalpy of sublimation of solid bromine is +40.1 kJ.mol ^- ¹ and the standard enthalpy of fusion of solid bromine is +10.6 kJ.mol ^- ¹.

Accepted Answer

The answer of Calculate the standard enthalpy of vaporization of...

Quiz 8: Thermodynamics: the First Law

Which of the following is not a state function?

Calculate the enthalpy change that occurs when 1 lb (454 g) of mercury freezes at its freezing point (234.3 K) .The standard enthalpy of fusion of mercury is 2.29 kJ.mol^-¹.

Calculate the final temperature when 2.50 kJ of energy is transferred as heat to 1.50 mol BF₃ at 298 K and 1 atm at constant pressure.

Calculate the change in internal energy when 2.50 kJ of energy is transferred as heat to 1.50 mol N₂ at 298 K and 1 atm at constant volume.

Calculate the enthalpy change that occurs when 1.00 kg of acetone condenses at its boiling point (329.4 K) .The standard enthalpy of vaporization of acetone is 29.1 kJ.mol^-¹.

Calculate the change in internal energy when 2.50 kJ of energy is transferred as heat to 1.50 mol BF₃ at 298 K and 1 atm at constant volume.

Calculate the change in internal energy when 2.50 kJ of energy is transferred as heat to 1.50 mol N₂ at 298 K and 1 atm at constant pressure.

Calculate the change in internal energy when 2.50 kJ of energy is transferred as heat to 1.50 mol BF₃ at 298 K and 1 atm at constant pressure.

When a solution of 1.691 g of silver nitrate is mixed with an excess of sodium chloride in a calorimeter of heat capacity 216 J.( $\degree$ C) 1^- ¹,the temperature rises 3.03 $\degree$ C.What is the reaction enthalpy?

Calculate the final temperature when 2.50 kJ of energy is transferred as heat to 1.50 mol BF₃ at 298 K and 1 atm at constant volume.

The combustion of one mole of octane,C₈H₁₈(l) ,in a bomb calorimeter released 5460 kJ of heat at 298 K.The products of the reaction are carbon dioxide and liquid water.What is the enthalpy change for this reaction?

The combustion of 1 mole of ethanol,C₂H₅OH(l) ,in a bomb calorimeter released 1240 kJ of heat.The products of the reaction are carbon dioxide and liquid water.What is the enthalpy change for this reaction?

The combustion of 1 mole of octane,C₈H₁₈(l) ,to produce carbon dioxide and liquid water has $\Delta$ H_r = -5471 kJ.mol ^- ¹ at 298 K.What is the change in internal energy for this reaction?

Calculate the final temperature when 2.50 kJ of energy is transferred as heat to 1.50 mol N₂ at 298 K and 1 atm at constant volume.

The combustion of 1 mole of ethanol,C₂H₅OH(l) ,to produce carbon dioxide and gaseous water has $\Delta$ H_r = -1235 kJ.mol^-¹ at 298 K.What is the change in internal energy for this reaction?

Calculate the final temperature when 2.50 kJ of energy is transferred as heat to 1.50 mol N₂ at 298 K and 1 atm at constant pressure.

Calculate the standard enthalpy of vaporization of liquid bromine if the standard enthalpy of sublimation of solid bromine is +40.1 kJ.mol ^- ¹ and the standard enthalpy of fusion of solid bromine is +10.6 kJ.mol ^- ¹.

Quiz 8: Thermodynamics: the First Law

Which of the following is not a state function?

Calculate the enthalpy change that occurs when 1 lb (454 g) of mercury freezes at its freezing point (234.3 K) .The standard enthalpy of fusion of mercury is 2.29 kJ.mol-1.

Calculate the final temperature when 2.50 kJ of energy is transferred as heat to 1.50 mol BF3 at 298 K and 1 atm at constant pressure.

Calculate the change in internal energy when 2.50 kJ of energy is transferred as heat to 1.50 mol N2 at 298 K and 1 atm at constant volume.

Calculate the enthalpy change that occurs when 1.00 kg of acetone condenses at its boiling point (329.4 K) .The standard enthalpy of vaporization of acetone is 29.1 kJ.mol-1.

Calculate the change in internal energy when 2.50 kJ of energy is transferred as heat to 1.50 mol BF3 at 298 K and 1 atm at constant volume.

Calculate the change in internal energy when 2.50 kJ of energy is transferred as heat to 1.50 mol N2 at 298 K and 1 atm at constant pressure.

Calculate the change in internal energy when 2.50 kJ of energy is transferred as heat to 1.50 mol BF3 at 298 K and 1 atm at constant pressure.

When a solution of 1.691 g of silver nitrate is mixed with an excess of sodium chloride in a calorimeter of heat capacity 216 J.( °\degree° C) 1- 1,the temperature rises 3.03 °\degree° C.What is the reaction enthalpy?

Calculate the final temperature when 2.50 kJ of energy is transferred as heat to 1.50 mol BF3 at 298 K and 1 atm at constant volume.

The combustion of one mole of octane,C8H18(l) ,in a bomb calorimeter released 5460 kJ of heat at 298 K.The products of the reaction are carbon dioxide and liquid water.What is the enthalpy change for this reaction?

The combustion of 1 mole of ethanol,C2H5OH(l) ,in a bomb calorimeter released 1240 kJ of heat.The products of the reaction are carbon dioxide and liquid water.What is the enthalpy change for this reaction?

The combustion of 1 mole of octane,C8H18(l) ,to produce carbon dioxide and liquid water has Δ\DeltaΔ Hr = -5471 kJ.mol - 1 at 298 K.What is the change in internal energy for this reaction?

Calculate the final temperature when 2.50 kJ of energy is transferred as heat to 1.50 mol N2 at 298 K and 1 atm at constant volume.

The combustion of 1 mole of ethanol,C2H5OH(l) ,to produce carbon dioxide and gaseous water has Δ\DeltaΔ Hr = -1235 kJ.mol-1 at 298 K.What is the change in internal energy for this reaction?

Calculate the final temperature when 2.50 kJ of energy is transferred as heat to 1.50 mol N2 at 298 K and 1 atm at constant pressure.

Calculate the standard enthalpy of vaporization of liquid bromine if the standard enthalpy of sublimation of solid bromine is +40.1 kJ.mol - 1 and the standard enthalpy of fusion of solid bromine is +10.6 kJ.mol - 1.

Calculate the enthalpy change that occurs when 1 lb (454 g) of mercury freezes at its freezing point (234.3 K) .The standard enthalpy of fusion of mercury is 2.29 kJ.mol^-¹.

Calculate the final temperature when 2.50 kJ of energy is transferred as heat to 1.50 mol BF₃ at 298 K and 1 atm at constant pressure.

Calculate the change in internal energy when 2.50 kJ of energy is transferred as heat to 1.50 mol N₂ at 298 K and 1 atm at constant volume.

Calculate the enthalpy change that occurs when 1.00 kg of acetone condenses at its boiling point (329.4 K) .The standard enthalpy of vaporization of acetone is 29.1 kJ.mol^-¹.

Calculate the change in internal energy when 2.50 kJ of energy is transferred as heat to 1.50 mol BF₃ at 298 K and 1 atm at constant volume.

Calculate the change in internal energy when 2.50 kJ of energy is transferred as heat to 1.50 mol N₂ at 298 K and 1 atm at constant pressure.

Calculate the change in internal energy when 2.50 kJ of energy is transferred as heat to 1.50 mol BF₃ at 298 K and 1 atm at constant pressure.

When a solution of 1.691 g of silver nitrate is mixed with an excess of sodium chloride in a calorimeter of heat capacity 216 J.( $\degree$ C) 1^- ¹,the temperature rises 3.03 $\degree$ C.What is the reaction enthalpy?

Calculate the final temperature when 2.50 kJ of energy is transferred as heat to 1.50 mol BF₃ at 298 K and 1 atm at constant volume.

The combustion of one mole of octane,C₈H₁₈(l) ,in a bomb calorimeter released 5460 kJ of heat at 298 K.The products of the reaction are carbon dioxide and liquid water.What is the enthalpy change for this reaction?

The combustion of 1 mole of ethanol,C₂H₅OH(l) ,in a bomb calorimeter released 1240 kJ of heat.The products of the reaction are carbon dioxide and liquid water.What is the enthalpy change for this reaction?

The combustion of 1 mole of octane,C₈H₁₈(l) ,to produce carbon dioxide and liquid water has $\Delta$ H_r = -5471 kJ.mol ^- ¹ at 298 K.What is the change in internal energy for this reaction?

Calculate the final temperature when 2.50 kJ of energy is transferred as heat to 1.50 mol N₂ at 298 K and 1 atm at constant volume.

The combustion of 1 mole of ethanol,C₂H₅OH(l) ,to produce carbon dioxide and gaseous water has $\Delta$ H_r = -1235 kJ.mol^-¹ at 298 K.What is the change in internal energy for this reaction?

Calculate the final temperature when 2.50 kJ of energy is transferred as heat to 1.50 mol N₂ at 298 K and 1 atm at constant pressure.

Calculate the standard enthalpy of vaporization of liquid bromine if the standard enthalpy of sublimation of solid bromine is +40.1 kJ.mol ^- ¹ and the standard enthalpy of fusion of solid bromine is +10.6 kJ.mol ^- ¹.