Q: A sample of metal with a mass of 24.8 g absorbs 275 J of energy, causing its temperature to rise from $$22.0\ ^\circ\mathrm{C} to$$ $$36.0\ ^\circ\mathrm{C}. $$What is the specific heat ($$c) of $$the metal? Use the formula $$q = mc\Delta T.$$

$$c = \dfrac{275}{24.8 \times (36.0 - 22.0)} = 0.80\ \mathrm{J/g\ ^\circ C}$$

Q: A cup of whole milk contains 13 g of carbohydrate, 9.0 g of fat, and 9.0 g of protein. Using the energy values $$4\ \mathrm{kcal/g}$$ for carbohydrate, $$9\ \mathrm{kcal/g}$$ for fat, and $$4\ \mathrm{kcal/g}$$ for protein, how many kilocalories does a cup of whole milk contain?

$$(13 \times 4) + (9.0 \times 9) + (9.0 \times 4) = 52 + 81 + 36 = 169\ \mathrm{kcal}$$

Q: A patient with hypothermia has a body temperature of $$34.0\ ^\circ\mathrm{C}. $$What is this temperature in degrees Fahrenheit? Use the formula $$^\circ\mathrm{F} = 1.8 \times ^\circ\mathrm{C} + 32.$$

$$^\circ\mathrm{F} = 1.8 \times 34.0 + 32 = 93.2\ ^\circ\mathrm{F}$$

Q: How much heat (in joules) is required to melt $$32.0\ \mathrm{g} of $$ice at $$0\ ^\circ\mathrm{C}$$? (Heat of fusion for water is $$334\ \mathrm{J/g})$$

$$32.0 \times 334 = 10,688\ \mathrm{J}$$

Question 1

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture in which the composition is uniform throughout and the different parts are not visible.

Question 2

Which of the following is an example of a chemical change?

Accepted Answer

Iron rusting in an old car.

Question 3

A sample of metal with a mass of 24.8 g absorbs 275 J of energy, causing its temperature to rise from $$22.0\ ^\circ\mathrm{C} to$$ $$36.0\ ^\circ\mathrm{C}. $$What is the specific heat ($$c) of $$the metal? Use the formula $$q = mc\Delta T.$$

Accepted Answer

$$c = \dfrac{275}{24.8 	imes (36.0 - 22.0)} = 0.80\ \mathrm{J/g\ ^\circ C}$$

Question 4

Which of the following statements about the Kelvin temperature scale is correct?

Accepted Answer

The Kelvin scale has no negative temperatures and absolute zero is $$0\ \mathrm{K}.$$

Question 5

A cup of whole milk contains 13 g of carbohydrate, 9.0 g of fat, and 9.0 g of protein. Using the energy values $$4\ \mathrm{kcal/g}$$ for carbohydrate, $$9\ \mathrm{kcal/g}$$ for fat, and $$4\ \mathrm{kcal/g}$$ for protein, how many kilocalories does a cup of whole milk contain?

Accepted Answer

$$(13 	imes 4) + (9.0 	imes 9) + (9.0 	imes 4) = 52 + 81 + 36 = 169\ \mathrm{kcal}$$

Question 6

Which of the following is a physical property?

Accepted Answer

Copper is a good conductor of electricity.

Question 7

Convert a body temperature of $$37.0\ ^\circ\mathrm{C} to $$Kelvin. Use the formula $$K = ^\circ\mathrm{C} + 273.15.$$

Accepted Answer

$$K = 37.0 + 273.15 = 310\ \mathrm{K}$$

Question 8

How many calories are obtained from a pat of butter if it provides $$150\ \mathrm{J} of $$energy when metabolized? (Use $$1\ \mathrm{cal} = 4.184\ \mathrm{J})$$

Accepted Answer

$$\dfrac{150}{4.184} = 36\ \mathrm{cal}$$

Question 9

Which of the following best describes the energy transformation when water at the top of a dam is released and flows downward?

Accepted Answer

Potential energy is converted to kinetic energy.

Question 10

Which of the following is a heterogeneous mixture?

Accepted Answer

Hot fudge sundae

Question 11

A patient with hypothermia has a body temperature of $$34.0\ ^\circ\mathrm{C}. $$What is this temperature in degrees Fahrenheit? Use the formula $$^\circ\mathrm{F} = 1.8 	imes ^\circ\mathrm{C} + 32.$$

Accepted Answer

$$^\circ\mathrm{F} = 1.8 	imes 34.0 + 32 = 93.2\ ^\circ\mathrm{F}$$

Question 12

How much heat (in joules) is required to melt $$32.0\ \mathrm{g} of $$ice at $$0\ ^\circ\mathrm{C}$$? (Heat of fusion for water is $$334\ \mathrm{J/g})$$

Accepted Answer

$$32.0 	imes 334 = 10,688\ \mathrm{J}$$

Question 13

Which of the following statements about changes of state is correct?

Accepted Answer

Sublimation is the process where a solid changes directly to a gas.

Question 14

A plateau (horizontal line) on a heating curve represents:

Accepted Answer

A constant temperature and a change of state.

Question 15

Which of the following is NOT a pure substance?

Accepted Answer

Air

Question 16

Which of the following best describes the physical state of a gas?

Accepted Answer

It has an indefinite shape and indefinite volume.

Question 17

How many kilojoules are released when $$50.0\ \mathrm{g} of $$steam condenses at $$100\ ^\circ\mathrm{C}$$? (Heat of vaporization for water is $$2.26\ \mathrm{kJ/g})$$

Accepted Answer

$$50.0 	imes 2.26 = 113\ \mathrm{kJ}$$

Question 18

Which of the following is an example of potential energy?

Accepted Answer

Gasoline in a gas tank.

Chapter 3: Matter and Energy – Study Notes for GOB Chemistry

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