Q: A $$50\ \mathrm{g}$$ sample of water is heated from $$20\ ^\circ\mathrm{C} to$$ $$70\ ^\circ\mathrm{C}. If $$the specific heat capacity of water is $$4.18\ \mathrm{J}/(\mathrm{g}\cdot ^\circ\mathrm{C})$$, how much heat is absorbed by the water?

$$Q = m \times c \times \Delta T = 50 \times 4.18 \times 50 = 10,450\ \mathrm{J}$$

Q: A $$100\ \mathrm{g}$$ sample of a substance is heated and its temperature increases by $$10\ ^\circ\mathrm{C}$$, absorbing $$2,000\ \mathrm{J} of $$heat. What is the specific heat capacity of the substance?

$$c = \dfrac{Q}{m \Delta T} = \dfrac{2,000}{100 \times 10} = 0.2\ \mathrm{J}/(\mathrm{g}\cdot ^\circ\mathrm{C})$$

Question 1

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture in which the components are so evenly mixed that the mixture appears as a single substance.

Question 2

A student heats a sample of ice at $$0\ ^\circ\mathrm{C}$$ until it becomes steam at $$100\ ^\circ\mathrm{C}. $$Which of the following best describes the changes that occur?

Accepted Answer

Only a physical change occurs.

Question 3

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

Accepted Answer

Iron reacts with oxygen to form rust.

Question 4

A sample of matter is compressible, has no fixed shape, and fills its container. Which state of matter is this sample in?

Accepted Answer

Gas

Question 5

Which separation technique would be most effective for separating a mixture of sand and water?

Accepted Answer

Filtration

Question 6

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 7

A chemical reaction absorbs $$150\ \mathrm{J} of $$energy from its surroundings. Which term best describes this reaction?

Accepted Answer

Endothermic

Question 8

Which of the following best describes potential energy?

Accepted Answer

Energy stored due to position or composition.

Question 9

A $$50\ \mathrm{g}$$ sample of water is heated from $$20\ ^\circ\mathrm{C} to$$ $$70\ ^\circ\mathrm{C}. If $$the specific heat capacity of water is $$4.18\ \mathrm{J}/(\mathrm{g}\cdot ^\circ\mathrm{C})$$, how much heat is absorbed by the water?

Accepted Answer

$$Q = m 	imes c 	imes \Delta T = 50 	imes 4.18 	imes 50 = 10,450\ \mathrm{J}$$

Question 10

Which of the following is NOT a pure substance?

Accepted Answer

Air

Question 11

Which of the following best explains why liquids have a fixed volume but no fixed shape?

Accepted Answer

The particles are close together but can move past one another.

Question 12

A student wants to separate a mixture of ethanol and water. Which method should they use and why?

Accepted Answer

Distillation, because ethanol and water have different boiling points.

Question 13

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

Accepted Answer

Dissolving sugar in water.

Question 14

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

Accepted Answer

A compound is made of two or more elements chemically combined, while an element consists of only one type of atom.

Question 15

A $$100\ \mathrm{g}$$ sample of a substance is heated and its temperature increases by $$10\ ^\circ\mathrm{C}$$, absorbing $$2,000\ \mathrm{J} of $$heat. What is the specific heat capacity of the substance?

Accepted Answer

$$c = \dfrac{Q}{m \Delta T} = \dfrac{2,000}{100 	imes 10} = 0.2\ \mathrm{J}/(\mathrm{g}\cdot ^\circ\mathrm{C})$$

Question 16

Which of the following best describes the difference between crystalline and amorphous solids?

Accepted Answer

Crystalline solids have atoms/molecules arranged in a long-range repeating order, while amorphous solids lack this order.

Question 17

Which of the following is the correct relationship between Celsius and Kelvin temperature scales?

Accepted Answer

$$K = ^\circ\mathrm{C} + 273.15$$

Question 18

Which of the following best describes chemical energy?

Accepted Answer

A form of potential energy stored in the positions of particles that compose a chemical system.

Question 19

A reaction produces $$500\ \mathrm{J} of $$heat and the temperature of the surroundings increases. Which term best describes this reaction?

Accepted Answer

Exothermic

Question 20

Which of the following statements about energy is correct according to the law of conservation of energy?

Accepted Answer

Energy is neither created nor destroyed, only transformed from one form to another.

Matter, States, Mixtures, and Energy: Foundations of Chemistry

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