# Thermodynamics Section 2 Quiz

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Questions: 10 | Attempts: 587  Settings  Quiz

• 1.

### Thermodynamic reactions play important roles in all of the following except...

• A.

Car engines

• B.

Refrigerators

• C.

Hitting baseballs

• D.

Cooking food

C. Hitting baseballs
Explanation
Thermodynamic reactions play important roles in car engines, refrigerators, and cooking food. However, hitting baseballs does not involve any thermodynamic reactions.

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• 2.

### What is a calorimeter?

• A.

A unit of calories per meter.

• B.

An insulated device used to measure the amount of heat absorbed or released during a chemical or physical process.

• C.

The amount of heat required to raise the temperature of one gram of pure water by one degree Celsius.

• D.

All of the above.

B. An insulated device used to measure the amount of heat absorbed or released during a chemical or physical process.
Explanation
A calorimeter is an insulated device used to measure the amount of heat absorbed or released during a chemical or physical process. It is designed to prevent any heat exchange with the surroundings, allowing for accurate measurement of the heat involved in a reaction or process. This device is commonly used in scientific experiments to determine the energy content of substances or to study the heat transfer in various processes. The other options provided in the question do not accurately define a calorimeter.

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• 3.

### What is the formula for measuring quantity of heat?

• A.

Q = c × m × ∆T

• B.

∆H rxn = H final - H initial

• C.

PV = nRT

• D.

F = ma

A. Q = c × m × ∆T
Explanation
The formula q = c × m × ∆T is the correct answer for measuring the quantity of heat. This equation represents the heat transfer, where q is the amount of heat transferred, c is the specific heat capacity of the substance, m is the mass of the substance, and ∆T is the change in temperature. By multiplying these values together, we can calculate the quantity of heat transferred in a system.

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• 4.

### Chemical reactions and physical changes that absorb energy from their surroundings are __________.

• A.

Isothermic

• B.

Exothermic

• C.

Endothermic

• D.

Mesothermic

C. Endothermic
Explanation
Endothermic reactions and physical changes absorb energy from their surroundings. This means that they require an input of energy to occur. During an endothermic process, energy is taken in from the surroundings, causing a decrease in temperature. Examples of endothermic reactions include the evaporation of water and the reaction between baking soda and vinegar.

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• 5.

### The universe is defined as the system plus the surroundings. universe = system + surroundings

• A.

True

• B.

False

A. True
Explanation
The statement is true because the universe is composed of both the system and its surroundings. The system refers to the specific object or area being studied, while the surroundings encompass everything else outside of the system that can potentially interact with it. To fully understand and analyze a system, it is necessary to consider the influence of its surroundings. Therefore, the equation "universe = system + surroundings" accurately represents the relationship between these components.

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• 6.

### The heat content of a system at constant pressure is defined as the ___________.

• A.

Entropy

• B.

Heat

• C.

Work

• D.

Enthalpy

D. Enthalpy
Explanation
Enthalpy is the correct answer because it is defined as the heat content of a system at constant pressure. It takes into account both the internal energy of the system and the work done on or by the system. Enthalpy is often used in thermodynamics to analyze and calculate heat transfer in chemical reactions and physical processes.

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• 7.

### What kind of energy transfers occurs during the heat-pack reaction?

• A.

Heat from the reaction flows from the heat pack (system) to the cold hands (surroundings)

• B.

Heat from the reaction flows from the heat pack (surroundings) to the cold hands (system)

• C.

Heat from the reaction flows from the cold hands (surroundings) into the heat pack (system)

• D.

None of the above

A. Heat from the reaction flows from the heat pack (system) to the cold hands (surroundings)
Explanation
The correct answer is "Heat from the reaction flows from the heat pack (system) to the cold hands (surroundings)." This is because heat is transferred from a higher temperature region (the heat pack) to a lower temperature region (the cold hands), following the principle of heat transfer from hot to cold.

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• 8.

### For the reaction below, the enthalpy change is +624.7 kJ. How would you classify this reaction? SiO2(g) + 3C(s) → SiC(s) + 2CO(g)

• A.

Endothermic reaction, heat is gained by the system

• B.

Exothermic reaction, heat is lost from the system

• C.

Endothermic reaction, heat is lost from the system

• D.

Exothermic reaction, heat is gained by the system

A. Endothermic reaction, heat is gained by the system
Explanation
The reaction is classified as an endothermic reaction because the enthalpy change is positive (+624.7 kJ). In an endothermic reaction, heat is gained by the system, meaning that energy is absorbed from the surroundings.

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• 9.

### Enthalpy changes for exothermic reactions are always positive.

• A.

True

• B.

False

B. False
Explanation
Enthalpy changes for exothermic reactions are always negative. This is because in an exothermic reaction, heat is released to the surroundings, resulting in a decrease in the potential energy of the system. Therefore, the change in enthalpy, which is a measure of the heat transfer in a reaction, is negative.

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• 10.

### A 75.0-g sample of a metal is place in boiling water until its temperature is 100.0°C. A calorimeter contains 100.00 g of water at a temperature of 24.4°C. The metal sample is removed from the boiling water and immediately placed in water in the calorimeter. The final temperature of the metal and water in the calorimeter is 34.9°C. Assuming that the calorimeter provides perfect insulation, what is the specific heat of the metal?

• A.

0.900 J/(g •°C)

• B.

0.900 J

• C.

1.11 J/(g •°C)

• D.

1.68 J Back to top