Q: A 2.0 kg object is moving at a velocity of 3.0 m/s. What is its kinetic energy?

$KE = \frac{1}{2}mv^2 = \frac{1}{2} \times 2.0 \times (3.0)^2 = 9.0\ J$

Q: If 83.65 J of heat is required to raise the temperature of 10.0 g of water by 2.00°C, what is the specific heat capacity $(c)$ of water?

$c = \frac{q}{m \Delta T} = \frac{83.65}{10.0 \times 2.00} = 4.18\ J/g\cdot ^\circ C$

Q: A gas expands from 0.100 L to 0.250 L against an external pressure of 1.00 atm. How much work is done by the gas?

$w = -P_{ext} \Delta V = -1.00\ atm \times (0.250 - 0.100)\ L = -0.150\ L\cdot atm$

Question 1

Which of the following best describes the Law of Conservation of Energy?

Accepted Answer

Energy can neither be created nor destroyed; it can only be transferred or transformed.

Question 2

A 2.0 kg object is moving at a velocity of 3.0 m/s. What is its kinetic energy?

Accepted Answer

$KE = \frac{1}{2}mv^2 = \frac{1}{2} 	imes 2.0 	imes (3.0)^2 = 9.0\ J$

Question 3

Which of the following is an example of potential energy?

Accepted Answer

The energy stored in a stretched spring.

Question 4

Which statement about thermal energy is correct?

Accepted Answer

Thermal energy is associated with the temperature of an object.

Question 5

What is the SI unit for energy, and how is it defined in terms of base units?

Accepted Answer

The SI unit for energy is the joule $(J)$, defined as $kg \cdot m^2 / s^2$.

Question 6

A chemical reaction releases 500 J of heat to the surroundings and performs 150 J of work on the surroundings. What is the change in internal energy $(\Delta E)$ of the system?

Accepted Answer

$\Delta E = q + w = -500\ J + (-150\ J) = -650\ J$

Question 7

Which of the following is a state function?

Accepted Answer

Internal energy

Question 8

If 83.65 J of heat is required to raise the temperature of 10.0 g of water by 2.00°C, what is the specific heat capacity $(c)$ of water?

Accepted Answer

$c = \frac{q}{m \Delta T} = \frac{83.65}{10.0 	imes 2.00} = 4.18\ J/g\cdot ^\circ C$

Question 9

Which process is endothermic?

Accepted Answer

Melting of ice into liquid water.

Question 10

A gas expands from 0.100 L to 0.250 L against an external pressure of 1.00 atm. How much work is done by the gas?

Accepted Answer

$w = -P_{ext} \Delta V = -1.00\ atm 	imes (0.250 - 0.100)\ L = -0.150\ L\cdot atm$

Question 11

Which of the following statements about enthalpy $(H)$ is correct?

Accepted Answer

Enthalpy is a state function and depends only on the initial and final states of the system.

Question 12

The standard enthalpy of formation of an element in its standard state is:

Accepted Answer

Always zero.

Question 13

Which of the following is NOT a form of potential energy?

Accepted Answer

Thermal energy

Question 14

A 35.0 g sample of metal at 133°C is placed in 100.0 g of water at 10.3°C. The final temperature is 15.4°C. What is the specific heat capacity $(c)$ of the metal? (Assume $c_{water} = 4.18\ J/g\cdot ^\circ C$)

Accepted Answer

$c_{metal} = \frac{m_{water} c_{water} (T_{final} - T_{water})}{m_{metal} (T_{metal} - T_{final})} = \frac{100.0 	imes 4.18 	imes (15.4 - 10.3)}{35.0 	imes (133.0 - 15.4)} = 0.13\ J/g\cdot ^\circ C$

Question 15

Which of the following is true about a system and its surroundings in thermodynamics?

Accepted Answer

The system is the part of the universe we are studying; the surroundings are everything else.

Question 16

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

Accepted Answer

$\Delta E = q + w$

Question 17

A reaction has $\Delta H = -250\ kJ$. Which statement is true?

Accepted Answer

The reaction is exothermic and releases heat to the surroundings.

Question 18

Which of the following is the correct conversion between calories and joules?

Accepted Answer

$1\ cal = 4.184\ J$

Question 19

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

Accepted Answer

Specific heat capacity is the amount of heat required to raise the temperature of 1 gram of a substance by 1°C.

Energy Types, Conservation, and Thermodynamics in General Chemistry

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