Calculate the internal energy change, ΔrU, for the combustion of 6.9261 g of diethylene glycol (C4H10O3, molar mass = 106.120 g mol-1) if the combustion inside a bomb calorimeter, Ccal = 13.84 kJ °C-1, causes a temperature change from 22.8 °C to 34.0 °C.

A) -4.39 × 103 kJ mol-1 B) -9.16 × 102 kJ mol-1 C) -2.37 × 103 kJ mol-1 D) 4.39 × 103 kJ mol-1 E) 1.18 × 103 kJ mol-1 A) -4.39 × 103 kJ mol-1 B) -9.16 × 102 kJ mol-1 C) -2.37 × 103 kJ mol-1 D) 4.39 × 103 kJ mol-1 E) 1.18 × 103 kJ mol-1

Exam 6: Thermochemistry

A 35.6 g sample of ethanol (C₂H₅OH) is burned in a bomb calorimeter according to the following reaction. If the temperature rose from 35.0 °C to 76.0°C and the heat capacity of the calorimeter is 23.3 kJ , what is the value of ΔU°? The molar mass of ethanol is 46.07 g . C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(g) ΔU°= ?

(Multiple Choice)

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Question 21

Which of the following is not a major contributor to energy consumption?

(Multiple Choice)

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Question 22

Calculate the internal energy change, Δ_rU, for the combustion of 6.9261 g of diethylene glycol (C₄H₁₀O₃, molar mass = 106.120 g mol^-1) if the combustion inside a bomb calorimeter, C_cal = 13.84 kJ °C^-1, causes a temperature change from 22.8 °C to 34.0 °C.

(Multiple Choice)

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Question 23

Explain the difference between ΔH and ΔU.

(Essay)

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Question 24

Describe the energy changes that occur when a book is held 1 m off the floor and then dropped.

(Essay)

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Question 25

A piece of iron (C = 0.449 J g^-1 °C^-1 and a piece of gold (C = 0.128 J g^-1 °C^-1) have identical masses. If the iron has an initial temperature of 498 K and the gold has an initial temperature of 298 K, which of the following statements is TRUE of the outcome when the two metals are placed in contact with one another? Assume no heat is lost to the surroundings.

(Multiple Choice)

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Question 26

An unknown metal alloy, mass = 36.1 g, has a temperature change of 31.6 to 24.8 °C after a heat transfer of -103.0 J. Calculate the specific heat capacity of the alloy.

(Multiple Choice)

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Question 27

Calculate the final temperature of 68.4 g of molecular hydrogen (specific heat capacity = 14.304 J g^-1 °C^-1) initially at 8.24 °C that releases 25.3 kJ of energy into the surroundings.

(Multiple Choice)

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Question 28

An unknown metal alloy, specific heat capacity = 0.613 J g^-1 °C^-1, has a temperature change of 31.02 to 24.77 °C after a heat transfer of -106.4 J. Calculate the mass of the alloy in question.

(Multiple Choice)

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Question 29

Which of the following processes is exothermic?

(Multiple Choice)

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Question 30

The temperature rises from 25.00 °C to 29.00 °C when 3.50 g of sucrose undergoes combustion in a bomb calorimeter. Calculate U for the combustion of sucrose in kJ sucrose. The heat capacity of the calorimeter is 4.90 kJ . The molar mass of sugar is 342.3 g .

(Multiple Choice)

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Question 31

Identify a substance that is in a non-standard state.

(Multiple Choice)

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Question 32

If a reaction is carried out at constant volume, then the change in internal energy of the chemical reaction is equal to the ________.

(Multiple Choice)

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Question 33

Define chemical energy.

(Essay)

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Question 34

The water at the top of a waterfall contains ________ energy.

(Multiple Choice)

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Question 35

Define specific heat capacity.

(Multiple Choice)

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Question 36

Which of the following processes is endothermic?

(Multiple Choice)

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Question 37

The specific heat of copper is 0.385 J . If 34.2 g of copper, initially at 21.0 °C, absorbs 4.689 kJ, what will be the final temperature of the copper?

(Multiple Choice)

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Question 38

Calculate the amount (mass) of acetic acid (C₂H₄O₂, molar mass = 60.052 g mol^-1) that causes a bomb calorimeter with a heat capacity of 8.43 kJ °C^-1 to have a temperature increase from 24.5 °C to 36.8 °C. The Δ_rU for the combustion of acetic acid is -874.2 kJ mol^-1.

(Multiple Choice)

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Question 39

When 1.50 mol of CH₄(g) reacts with excess Cl₂(g) at constant pressure according to the chemical equation shown below, 1062 kJ of heat are released. Calculate the value of ΔH for this reaction, as written. 2CH₄(g) + 3Cl₂(g) → 2CHCl₃(l) + 3H₂(g) H° = ?

(Multiple Choice)

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Question 40

Showing 21 - 40 of 161

Exam 6: Thermochemistry

Which of the following is not a major contributor to energy consumption?

Calculate the internal energy change, ΔrU, for the combustion of 6.9261 g of diethylene glycol (C4H10O3, molar mass = 106.120 g mol-1) if the combustion inside a bomb calorimeter, Ccal = 13.84 kJ °C-1, causes a temperature change from 22.8 °C to 34.0 °C.

Explain the difference between ΔH and ΔU.

Describe the energy changes that occur when a book is held 1 m off the floor and then dropped.

An unknown metal alloy, mass = 36.1 g, has a temperature change of 31.6 to 24.8 °C after a heat transfer of -103.0 J. Calculate the specific heat capacity of the alloy.

Calculate the final temperature of 68.4 g of molecular hydrogen (specific heat capacity = 14.304 J g-1 °C-1) initially at 8.24 °C that releases 25.3 kJ of energy into the surroundings.

An unknown metal alloy, specific heat capacity = 0.613 J g-1 °C-1, has a temperature change of 31.02 to 24.77 °C after a heat transfer of -106.4 J. Calculate the mass of the alloy in question.

Which of the following processes is exothermic?

The temperature rises from 25.00 °C to 29.00 °C when 3.50 g of sucrose undergoes combustion in a bomb calorimeter. Calculate U for the combustion of sucrose in kJ sucrose. The heat capacity of the calorimeter is 4.90 kJ . The molar mass of sugar is 342.3 g .

Identify a substance that is in a non-standard state.

If a reaction is carried out at constant volume, then the change in internal energy of the chemical reaction is equal to the ________.

Define chemical energy.

The water at the top of a waterfall contains ________ energy.

Define specific heat capacity.

Which of the following processes is endothermic?

The specific heat of copper is 0.385 J . If 34.2 g of copper, initially at 21.0 °C, absorbs 4.689 kJ, what will be the final temperature of the copper?

Calculate the amount (mass) of acetic acid (C2H4O2, molar mass = 60.052 g mol-1) that causes a bomb calorimeter with a heat capacity of 8.43 kJ °C-1 to have a temperature increase from 24.5 °C to 36.8 °C. The ΔrU for the combustion of acetic acid is -874.2 kJ mol-1.

When 1.50 mol of CH4(g) reacts with excess Cl2(g) at constant pressure according to the chemical equation shown below, 1062 kJ of heat are released. Calculate the value of ΔH for this reaction, as written. 2CH4(g) + 3Cl2(g) → 2CHCl3(l) + 3H2(g) H° = ?

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Calculate the internal energy change, Δ_rU, for the combustion of 6.9261 g of diethylene glycol (C₄H₁₀O₃, molar mass = 106.120 g mol^-1) if the combustion inside a bomb calorimeter, C_cal = 13.84 kJ °C^-1, causes a temperature change from 22.8 °C to 34.0 °C.

Calculate the final temperature of 68.4 g of molecular hydrogen (specific heat capacity = 14.304 J g^-1 °C^-1) initially at 8.24 °C that releases 25.3 kJ of energy into the surroundings.

An unknown metal alloy, specific heat capacity = 0.613 J g^-1 °C^-1, has a temperature change of 31.02 to 24.77 °C after a heat transfer of -106.4 J. Calculate the mass of the alloy in question.

Calculate the amount (mass) of acetic acid (C₂H₄O₂, molar mass = 60.052 g mol^-1) that causes a bomb calorimeter with a heat capacity of 8.43 kJ °C^-1 to have a temperature increase from 24.5 °C to 36.8 °C. The Δ_rU for the combustion of acetic acid is -874.2 kJ mol^-1.

When 1.50 mol of CH₄(g) reacts with excess Cl₂(g) at constant pressure according to the chemical equation shown below, 1062 kJ of heat are released. Calculate the value of ΔH for this reaction, as written. 2CH₄(g) + 3Cl₂(g) → 2CHCl₃(l) + 3H₂(g) H° = ?