Q: A 2.5 g sample of gallium is heated from 25.0$$^ ext{o}C to 29.9$^ ext{o}C. If $$the specific heat capacity of gallium is 0.372 J/g$$^ ext{o}C$$, how much heat ($$q) is $$absorbed? Use $$q = mC\Delta T.$$

$$q = 2.5 \times 0.372 \times (29.9 - 25.0) = 4.6 J$$

Q: A candy bar contains 225 Cal of nutritional energy. How many joules does it contain? (1 Cal = 1000 cal, 1 cal = 4.184 J)

$$225 \times 1000 \times 4.184 = 941,400 J$$

Question 1

Which of the following best describes a compound?

Accepted Answer

A pure substance composed of two or more elements in fixed, definite proportions.

Question 2

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

Accepted Answer

Boiling water to produce steam.

Question 3

A sample of butane (C$$_4H$_{10}) $$weighing 58 g reacts with 208 g of oxygen to produce 176 g of carbon dioxide and 90 g of water. Which law does this observation illustrate?

Accepted Answer

Law of Conservation of Mass

Question 4

Which of the following statements about gases is FALSE?

Accepted Answer

Gases have a fixed volume and shape.

Question 5

Which of the following is a chemical property?

Accepted Answer

The flammability of gasoline.

Question 6

Which separation technique would be most appropriate to separate a mixture of sand and saltwater?

Accepted Answer

Filtration

Question 7

A 2.5 g sample of gallium is heated from 25.0$$^	ext{o}C to 29.9$^	ext{o}C. If $$the specific heat capacity of gallium is 0.372 J/g$$^	ext{o}C$$, how much heat ($$q) is $$absorbed? Use $$q = mC\Delta T.$$

Accepted Answer

$$q = 2.5 	imes 0.372 	imes (29.9 - 25.0) = 4.6 J$$

Question 8

Which of the following best describes an exothermic reaction?

Accepted Answer

A reaction in which energy is released to the surroundings.

Question 9

Convert 25$$^	ext{o}C to $$Kelvin using the correct formula.

Accepted Answer

$$K = 25 + 273 = 298 K$$

Question 10

Which of the following is a homogeneous mixture?

Accepted Answer

A glass of sweetened tea with all sugar dissolved

Question 11

Which of the following statements about energy is TRUE?

Accepted Answer

Energy can be transferred from one object to another.

Question 12

A candy bar contains 225 Cal of nutritional energy. How many joules does it contain? (1 Cal = 1000 cal, 1 cal = 4.184 J)

Accepted Answer

$$225 	imes 1000 	imes 4.184 = 941,400 J$$

Question 13

Which of the following is NOT a physical property?

Accepted Answer

The tendency of iron to rust.

Question 14

Which of the following best describes a crystalline solid?

Accepted Answer

Atoms or molecules are arranged in a well-ordered, repeating three-dimensional structure.

Question 15

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

Accepted Answer

Burning a piece of paper.

Question 16

Which of the following statements about temperature and heat is correct?

Accepted Answer

Heat is the transfer of thermal energy due to a temperature difference.

Question 17

Which of the following is a heterogeneous mixture?

Accepted Answer

Oil and water

Question 18

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

Accepted Answer

$$q = mC\Delta T$$

Question 19

Which of the following is an example of potential energy?

Accepted Answer

A compressed spring

Question 20

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

Accepted Answer

Absolute zero (0 K) is the temperature at which molecular motion virtually stops.

Chapter 3: Matter and Energy – Structured Study Notes for Introductory Chemistry

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