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

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

Q: If 1 calorie is equal to $$4.184\ \mathrm{J}$$, how many joules are in $$250\ \mathrm{cal}$$?

$$250 \times 4.184 = 1046\ \mathrm{J}$$

Question 1

Which of the following best describes the difference between kinetic and potential energy in a chemical system?

Accepted Answer

Kinetic energy is the energy associated with the motion of particles, while potential energy is the energy associated with the position or composition of particles.

Question 2

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

Accepted Answer

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

Question 3

Which of the following is an example of potential energy in a chemical system?

Accepted Answer

The energy stored in the bonds of glucose molecules

Question 4

According to the Law of Conservation of Energy, which statement is correct?

Accepted Answer

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

Question 5

Which of the following best defines a 'system' in thermodynamics?

Accepted Answer

That which is of interest, the part we are studying or investigating.

Question 6

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

Accepted Answer

The SI unit of energy is the joule, defined as $$\mathrm{kg} \cdot \mathrm{m}^2/\mathrm{s}^2.$$

Question 7

If 1 calorie is equal to $$4.184\ \mathrm{J}$$, how many joules are in $$250\ \mathrm{cal}$$?

Accepted Answer

$$250 	imes 4.184 = 1046\ \mathrm{J}$$

Question 8

Which of the following is a correct statement of the First Law of Thermodynamics?

Accepted Answer

The total energy of the universe is constant.

Question 9

A chemical reaction releases $$500\ \mathrm{J} of $$heat to the surroundings and does $$200\ \mathrm{J} of $$work on the surroundings. What is the change in internal energy ($$\Delta E) of $$the system?

Accepted Answer

$$\Delta E = q + w = -500\ \mathrm{J} + (-200\ \mathrm{J}) = -700\ \mathrm{J}$$

Question 10

Which of the following is a state function?

Accepted Answer

Internal energy

Question 11

A gas expands from $$0.50\ \mathrm{L} to$$ $$1.50\ \mathrm{L}$$ against a constant external pressure of $$1.00\ \mathrm{atm}. $$How much work is done by the gas? ($$1\ \mathrm{L} \cdot \mathrm{atm} = 101.3\ \mathrm{J})$$

Accepted Answer

$$w = -P_{ext} \Delta V = -(1.00)(1.50-0.50) = -1.00\ \mathrm{L} \cdot \mathrm{atm} = -101.3\ \mathrm{J}$$

Question 12

Which of the following best describes thermal energy?

Accepted Answer

Thermal energy is a type of kinetic energy associated with the temperature of an object.

Question 13

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

Accepted Answer

Thermal energy

Question 14

A system absorbs $$300\ \mathrm{J} of $$heat from the surroundings and has $$100\ \mathrm{J} of $$work done on it by the surroundings. What is the change in internal energy ($$\Delta E$$)?

Accepted Answer

$$\Delta E = q + w = 300\ \mathrm{J} + 100\ \mathrm{J} = 400\ \mathrm{J}$$

Question 15

Which of the following scenarios best illustrates the concept of energy exchange between a system and its surroundings?

Accepted Answer

A chemical reaction in a beaker that releases heat to the air.

Question 16

Which of the following is the correct relationship for the kinetic energy of an object with mass $$m$$ moving at velocity $$v$$?

Accepted Answer

$$KE = \frac{1}{2} m v^2$

Question 17

Which of the following is true about the internal energy ($$E) of a $$system?

Accepted Answer

It is the sum of the kinetic and potential energies of all the particles in the system.

Question 18

Which of the following best describes the surroundings in a thermodynamic process?

Accepted Answer

Everything with which the system can exchange energy.

Question 19

A student calculates the kinetic energy of a 0.50 kg ball moving at 4.0 m/s. Which calculation is correct?

Accepted Answer

$$KE = \frac{1}{2} 	imes 0.50 	imes (4.0)^2$ = 4.0\ \mathrm{J}$$

Energy, Thermodynamics, and Systems in General Chemistry

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