Q: A 50.0 g sample of water is heated from $$20.0\ ^\circ\mathrm{C} to$$ $$80.0\ ^\circ\mathrm{C}. If $$the specific heat capacity of water is $$4.18\ \mathrm{J/g\cdot ^\circ C}$$, how much heat energy ($$q) is $$absorbed?

$$q = 50.0 \times 4.18 \times (80.0 - 20.0) = 12,540\ \mathrm{J}$$

Q: A 100.0 g sample of a metal is heated from $$25.0\ ^\circ\mathrm{C} to$$ $$75.0\ ^\circ\mathrm{C}$$, absorbing $$2,000\ \mathrm{J} of $$heat. What is the specific heat capacity ($$c) of $$the metal?

$$c = \dfrac{2,000}{100.0 \times (75.0 - 25.0)} = 0.40\ \mathrm{J/g\cdot ^\circ C}$$

Question 1

Which of the following best describes an amorphous solid?

Accepted Answer

A solid whose particles are arranged randomly and lack a long-range order.

Question 2

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

Accepted Answer

Burning of wood in a fireplace.

Question 3

A sample of matter is uniform throughout and can be separated into two substances by a chemical process but not by a physical process. How should this sample be classified?

Accepted Answer

Compound

Question 4

Which of the following statements is consistent with the law of conservation of mass?

Accepted Answer

The total mass of reactants equals the total mass of products in a chemical reaction.

Question 5

Which of the following is a physical property?

Accepted Answer

Density

Question 6

A 50.0 g sample of water is heated from $$20.0\ ^\circ\mathrm{C} to$$ $$80.0\ ^\circ\mathrm{C}. If $$the specific heat capacity of water is $$4.18\ \mathrm{J/g\cdot ^\circ C}$$, how much heat energy ($$q) is $$absorbed?

Accepted Answer

$$q = 50.0 	imes 4.18 	imes (80.0 - 20.0) = 12,540\ \mathrm{J}$$

Question 7

Which of the following best describes an exothermic reaction?

Accepted Answer

A reaction that releases heat to the surroundings.

Question 8

A student mixes two clear solutions and observes the formation of a solid precipitate. Which type of change has occurred?

Accepted Answer

Chemical change

Question 9

Which of the following is a correct conversion between temperature scales?

Accepted Answer

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

Question 10

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture in which the composition is uniform throughout.

Question 11

Which of the following is an example of potential energy?

Accepted Answer

A compressed spring.

Question 12

A chemical reaction in a closed container releases 500 J of heat to the surroundings. According to the law of conservation of energy, what happens to the total energy of the system and surroundings?

Accepted Answer

The total energy remains constant.

Question 13

Which of the following best describes the difference between an element and a compound?

Accepted Answer

A compound consists of two or more elements chemically combined in a fixed ratio, while an element consists of only one type of atom.

Question 14

A 100.0 g sample of a metal is heated from $$25.0\ ^\circ\mathrm{C} to$$ $$75.0\ ^\circ\mathrm{C}$$, absorbing $$2,000\ \mathrm{J} of $$heat. What is the specific heat capacity ($$c) of $$the metal?

Accepted Answer

$$c = \dfrac{2,000}{100.0 	imes (75.0 - 25.0)} = 0.40\ \mathrm{J/g\cdot ^\circ C}$$

Question 15

Which of the following scenarios best illustrates the law of conservation of mass?

Accepted Answer

A piece of iron rusts in a closed container, and the total mass remains unchanged.

Question 16

Which of the following is a correct statement about kinetic energy?

Accepted Answer

Kinetic energy is the energy of motion, given by $$KE = \dfrac{1}{2}mv^2$.

Question 17

A student wants to convert a temperature of $$68\ ^\circ\mathrm{F} to $$Celsius. Which formula should they use?

Accepted Answer

$$^\circ C = ( ^\circ F - 32 ) 	imes \dfrac{5}{9}$$

Question 18

Which of the following is an example of an endothermic process?

Accepted Answer

Melting of ice in a drink.

Question 19

A 200.0 g sample of ethanol at $$25.0\ ^\circ\mathrm{C}$$ absorbs $$4,180\ \mathrm{J} of $$heat. If the specific heat capacity of ethanol is $$2.44\ \mathrm{J/g\cdot ^\circ C}$$, what is the final temperature of the ethanol?

Accepted Answer

$$\Delta T = \dfrac{4,180}{200.0 	imes 2.44} = 8.57\ ^\circ\mathrm{C}$$; \ Final\ T = 25.0 + 8.57 = 33.6\ ^\circ\mathrm{C}$

Question 20

Which of the following best explains why gases are easily compressed compared to solids and liquids?

Accepted Answer

Gas particles are much farther apart than those in solids and liquids.

Matter, Energy, and Their Properties: Foundations of Chemistry

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