Q: A sample of water at 25°C has a density of 0.997 g/mL. If a swimming pool holds 346 L of water at this temperature, what is the mass of water in the pool?

$$m = (0.997 \ g/mL) \times (346 \ L \times \frac{1000 \ mL}{1 \ L}) = 344,662 \ g \approx 345 \ kg$$

Q: A 207-g sample of iron absorbs 1.50 kJ of heat. The specific heat of iron is 0.449 J/g·°C. What is the change in temperature of the iron?

$$\Delta T = \frac{1,500 \ J}{207 \ g \times 0.449 \ J/g\cdot ^\circ C} = 16.1 \ ^\circ C$$

Question 1

Which of the following best describes a chemical property?

Accepted Answer

The ability of a substance to change its identity during a chemical reaction.

Question 2

A sample of water at 25°C has a density of 0.997 g/mL. If a swimming pool holds 346 L of water at this temperature, what is the mass of water in the pool?

Accepted Answer

$$m = (0.997 \ g/mL) 	imes (346 \ L 	imes \frac{1000 \ mL}{1 \ L}) = 344,662 \ g \approx 345 \ kg$$

Question 3

Which of the following changes is an example of a physical change?

Accepted Answer

Boiling water to produce steam.

Question 4

Which equation correctly relates Celsius and Kelvin temperature scales?

Accepted Answer

$$K = ^\circ C + 273.15$$

Question 5

A 24.0-g aluminum can raises its temperature by 15.0°C. The specific heat of aluminum is 0.900 J/g·°C. What is the value of $$q$$ for the can?

Accepted Answer

$$q = (24.0 \ g)(0.900 \ J/g\cdot ^\circ C)(15.0 \ ^\circ C) = 324 \ J$$

Question 6

Which of the following statements about exothermic reactions is correct?

Accepted Answer

Exothermic reactions release heat and result in a decrease in the enthalpy of the system.

Question 7

A gas does 218 J of work while absorbing 515 J of heat from the surroundings. What is the change in internal energy ($$\Delta E) of $$the system?

Accepted Answer

$$\Delta E = 515 \ J + (-218 \ J) = 297 \ J$$

Question 8

Which of the following is a correct application of Hess's Law?

Accepted Answer

The enthalpy change for a reaction is the sum of the enthalpy changes for each step, regardless of the path.

Question 9

Which of the following is NOT a base unit in the SI system?

Accepted Answer

Liter (L)

Question 10

A 207-g sample of iron absorbs 1.50 kJ of heat. The specific heat of iron is 0.449 J/g·°C. What is the change in temperature of the iron?

Accepted Answer

$$\Delta T = \frac{1,500 \ J}{207 \ g 	imes 0.449 \ J/g\cdot ^\circ C} = 16.1 \ ^\circ C$$

Question 11

Which of the following best describes a state function?

Accepted Answer

A property that depends only on the initial and final states of a system, not on the path taken.

Question 12

Which of the following equations correctly expresses the relationship between heat ($$q$$), mass ($$m$$), specific heat ($$c$$), and temperature change ($$\Delta T$$)?

Accepted Answer

$$q = mc\Delta T$$

Question 13

A reaction occurs at constant pressure and releases 285.8 kJ of heat. What is the sign of $$\Delta H$$ and is the reaction exothermic or endothermic?

Accepted Answer

$$\Delta H \u003c 0$$, exothermic

Question 14

Which of the following is a correct mole ratio from the balanced equation for the combustion of methane: $$CH_4 + 2$$ $$O_2$$ \rightarrow $$CO_2 + 2 H_2O$?

Accepted Answer

$$1 \ mol \ CH_4$ : 2 \ mol \ O_2$

Question 15

If 6.75 mol of $$CH_4 is $$completely combusted, how many moles of $$H_2O$$ are formed?

Accepted Answer

$$6.75 \ mol \ CH_4$ 	imes \frac{2 \ mol \ H_2O}{1 \ mol \ CH_4$} = 13.5 \ mol \ H_2O$$

Question 16

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

Accepted Answer

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

Question 17

A 250.0 g sample of water at 78.0°C is mixed with a gold sample at 2.30°C. The final temperature is 76.9°C. The specific heat of water is 4.184 J/g·°C and gold is 0.129 J/g·°C. What was the mass of gold?

Accepted Answer

$$m = \frac{1,150.6 \ J}{9.62 \ J/g} = 119.6 \ g$$

Question 18

Which of the following is a derived SI unit?

Accepted Answer

Joule (J)

Fundamental Concepts and Principles in General Chemistry

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