Question 1

Which of the following best describes a closed system as shown in the piston diagram?

Accepted Answer

A system that can exchange energy (as heat or work) but not matter with its surroundings.

Question 2

In the reaction $$\mathrm{H_2$(g) + O_2$(g) \rightarrow H_2O(l)}$$, the internal energy change $$\Delta E is $$negative. What does this indicate about the energy flow?

Accepted Answer

Energy is released from the system to the surroundings.

Question 3

A battery is used to power a motor, as shown in the diagram. Which form(s) of energy are transferred from the battery to the motor?

Accepted Answer

Both heat and work energy are transferred.

Question 4

Which of the following statements about state functions is correct?

Accepted Answer

State functions depend only on the current state, not the method used to reach it.

Question 5

A sample of calcium carbonate absorbs 45.5 J of heat, and its temperature increases from 21.1 °C to 28.5 °C. If the specific heat of calcium carbonate is 0.82 J/g°C, what is the mass of the sample?

Accepted Answer

B) 5.0 g

Question 6

Which of the following processes is endothermic?

Accepted Answer

Both ice melting and boiling soup

Question 7

If a system gains 89 kJ of heat and does 111 kJ of work on its surroundings, what is $$\Delta E$$ for the system?

Accepted Answer

$$\Delta E = -22\ \mathrm{kJ}$$

Question 8

Which condition would always result in an increase in the internal energy of a system?

Accepted Answer

The system gains heat and has work done on it by the surroundings.

Question 9

A metal sample with mass 32.91 g absorbs 235 J of heat, causing its temperature to rise by 2.53 °C. What is the specific heat $$C_s of $$the metal?

Accepted Answer

$$C_s = 2.80\ \mathrm{J/(g\,°C)}$$

Question 10

Which of the following is NOT a state function?

Accepted Answer

Heat ($$q)$$

Question 11

A cup of water with heat capacity 720 J/°C is heated from 19.2 °C to 23.5 °C. How much heat is absorbed?

Accepted Answer

$$q = 3,240\ \mathrm{J}$$

Question 12

Which scenario best illustrates an exothermic reaction?

Accepted Answer

Heat flows from the system into the surroundings, increasing the temperature of the surroundings.

Question 13

Which equation correctly relates internal energy change ($$\Delta E$$), heat ($$q$$), and work ($$w$$)?

Accepted Answer

$$\Delta E = q + w$$

Question 14

If a system releases heat to the surroundings and has work done on it by the surroundings, what is the sign of $$q$$ and $$w$$?

Accepted Answer

$$q  0$$

Question 15

Which property is an extensive property?

Accepted Answer

Heat capacity ($$C)$$

Question 16

A reaction in a beaker causes the temperature of the beaker and surrounding air to drop. What type of process is this?

Accepted Answer

Endothermic

Question 17

Which of the following is true about the first law of thermodynamics?

Accepted Answer

Energy can be converted from one form to another, but cannot be created or destroyed.

Question 18

Which of the following is an example of an open system?

Accepted Answer

A boiling pot of water where steam escapes and heat is transferred.

Question 19

If doubling the amount of a substance doubles its heat capacity, what type of property is heat capacity?

Accepted Answer

Extensive property

Question 20

Which of the following is a correct statement about specific heat?

Accepted Answer

Specific heat is unique to each substance and is an intensive property.

Chapter 5: Thermochemistry – Energy, Heat, and Chemical Reactions

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