Q: A 1.00 kW electric heater is used for 2.00 hours. How much energy is consumed in kilowatt-hours (kWh) and joules (J)?

2.00 kWh and $$7.20 \times 10^6$ J

Question 1

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

Accepted Answer

Potential energy is the energy due to position or composition, while kinetic energy is due to movement.

Question 2

A 22.05 g solid is heated to 100.00°C and placed in 50.00 g of water at 25.10°C. The final temperature is 28.49°C. If the specific heat capacity of water is $$4.184 \ \mathrm{J/g\cdot ^\circ C}$$, what is the specific heat capacity of the solid? (Assume no heat is lost to the surroundings.)

Accepted Answer

$$c_{solid} = \frac{(50.00\,\mathrm{g})(4.184\,\mathrm{J/g\cdot ^\circ C})(28.49-25.10)}{22.05\,\mathrm{g}(100.00-28.49)}$$

Question 3

Which of the following phase changes is exothermic?

Accepted Answer

Condensation

Question 4

A gas is contained in a rigid, sealed container. If the temperature of the gas is doubled (in Kelvin), what happens to the pressure?

Accepted Answer

The pressure doubles.

Question 5

Which of the following statements about hydrogen bonding is correct?

Accepted Answer

Hydrogen bonding only occurs in molecules containing N-H, O-H, or F-H bonds and a lone pair on N, O, or F.

Question 6

Which of the following equations correctly expresses the ideal gas law?

Accepted Answer

$$PV = nRT$$

Question 7

A sample of gas occupies 10.0 L at 2.00 atm and 300 K. What will be its volume at 1.00 atm and 300 K, assuming the amount of gas remains constant?

Accepted Answer

20.0 L

Question 8

Which of the following best explains why water has a much higher boiling point than methane ($$CH_4$$)?

Accepted Answer

Water forms hydrogen bonds, which are much stronger than the London dispersion forces in methane.

Question 9

Which of the following is the correct relationship for calculating the amount of heat absorbed or released by a substance?

Accepted Answer

$$q = mc\Delta T$$

Question 10

A mixture of gases contains 2.0 mol $$N_2$$, 1.0 mol $$O_2$$, and 1.0 mol $$CO_2 at a $$total pressure of 2.0 atm. What is the partial pressure of $$O_2$$?

Accepted Answer

0.5 atm

Question 11

Which of the following is NOT a property of gases?

Accepted Answer

They have a definite volume.

Question 12

Which of the following intermolecular forces is generally the strongest?

Accepted Answer

Ion-ion

Question 13

A 100.0 g sample of water at 25.0°C absorbs 4184 J of heat. What is the final temperature of the water? ($$c_{H_2O} = 4.184 \ \mathrm{J/g\cdot ^\circ C})$$

Accepted Answer

35.0°C

Question 14

Which of the following best describes an exothermic reaction?

Accepted Answer

A reaction that releases heat to the surroundings.

Question 15

Which of the following is true about the specific heat capacity of a substance?

Accepted Answer

It is the amount of heat required to change the temperature of 1 gram of the substance by 1°C.

Question 16

Which of the following best explains why gases are compressible while solids are not?

Accepted Answer

Gas particles are far apart and disorganized, while solid particles are close together and organized.

Question 17

Which of the following is the correct unit conversion for energy?

Accepted Answer

1 cal = 4.184 J

Question 18

Which of the following is a real-life example of an endothermic process?

Accepted Answer

Ice melting in a drink

Question 19

Which of the following best describes the difference between intramolecular and intermolecular forces?

Accepted Answer

Intramolecular forces are found within a molecule and control chemical properties, while intermolecular forces are found between molecules and control physical properties.

Question 20

A 1.00 kW electric heater is used for 2.00 hours. How much energy is consumed in kilowatt-hours (kWh) and joules (J)?

Accepted Answer

2.00 kWh and $$7.20 	imes 10^6$ J

Energy and Physical Properties: Study Notes for General Chemistry

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