Q: A person weighing 75.0 kg runs at a speed of 1.78 m/s. What is their kinetic energy?

$$E_K = \frac{1}{2} \times 75.0 \times (1.78)^2$ = 119\ \mathrm{J}$$

Question 1

Which of the following best describes the first law of thermodynamics?

Accepted Answer

Energy cannot be created or destroyed, only transformed from one form to another.

Question 2

A chemical reaction occurs in a closed flask. Which statement is true about the system and its surroundings?

Accepted Answer

The system is the reaction mixture inside the flask, and the surroundings are everything outside the flask.

Question 3

Which equation correctly expresses the first law of thermodynamics for a system?

Accepted Answer

$$\Delta U = q + w$$

Question 4

A person weighing 75.0 kg runs at a speed of 1.78 m/s. What is their kinetic energy?

Accepted Answer

$$E_K = \frac{1}{2} 	imes 75.0 	imes (1.78)^2$ = 119\ \mathrm{J}$$

Question 5

Which of the following is an example of an exothermic process?

Accepted Answer

Burning firewood in a fireplace.

Question 6

In the reaction $$\mathrm{CH_4$(g) + 2O_2(g) \rightarrow CO_2$(g) + 2H_2O(l)}$$ with a heat of reaction $$\Delta H = -890\ \mathrm{kJ}$$, what does the negative sign indicate?

Accepted Answer

The reaction releases 890 kJ of heat to the surroundings.

Question 7

Which of the following is a state function?

Accepted Answer

Internal energy ($$U) of $$the system.

Question 8

Which statement about state functions is correct?

Accepted Answer

State functions depend only on the current state of the system, not the path.

Question 9

Which of the following is an extensive property?

Accepted Answer

Volume ($$V)$$

Question 10

A reaction vessel gets cold during a chemical reaction. What can you conclude about the process?

Accepted Answer

The reaction is endothermic.

Question 11

Which of the following best describes temperature in thermodynamics?

Accepted Answer

Temperature is a measure of a particle's average kinetic energy.

Question 12

Which type of system allows both mass and energy to be exchanged with its surroundings?

Accepted Answer

Open system

Question 13

Which formula represents gravitational potential energy?

Accepted Answer

$$E_p = mgh$$

Question 14

During an endothermic reaction in a closed container, what happens to the temperature of the surroundings?

Accepted Answer

It decreases.

Question 15

Which of the following is NOT a state variable?

Accepted Answer

Heat ($$q)$$

Question 16

If a system does 50 J of work on the surroundings and absorbs 30 J of heat, what is the change in internal energy ($$\Delta U$$)?

Accepted Answer

$$\Delta U = 30 - 50 = -20\ \mathrm{J}$$

Question 17

Which process involves energy being transferred from the system to the surroundings as heat?

Accepted Answer

Exothermic process

Question 18

Which of the following statements about bond breaking and bond making is correct?

Accepted Answer

Bond breaking requires energy, and bond making releases energy.

Question 19

Which of the following is true for an isolated system?

Accepted Answer

Neither mass nor energy can enter or leave.

Question 20

Which of the following is an intensive property?

Accepted Answer

Pressure ($$P)$$

Thermodynamics and Thermochemistry: Systems, State Functions, and Energy Changes

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