Q: A sample of water is heated from $$25\ ^\circ\mathrm{C} to$$ $$75\ ^\circ\mathrm{C}. If $$the mass of the water is $$100\ \mathrm{g}$$ and the specific heat capacity is $$4.18\ \mathrm{J/g\ ^\circ C}$$, how much heat is absorbed?

$$q = 100 \times 4.18 \times (75 - 25) = 20,900\ \mathrm{J}$$

Question 1

Which of the following best describes a compound?

Accepted Answer

A substance composed of two or more different elements chemically bonded in fixed proportions.

Question 2

Which separation technique would be most effective for isolating salt from a mixture of sand, salt, and water?

Accepted Answer

Filtration followed by distillation.

Question 3

Which of the following is NOT a physical property?

Accepted Answer

Flammability

Question 4

A student observes a color change and the production of a gas when two clear solutions are mixed. What type of change has most likely occurred?

Accepted Answer

A chemical change

Question 5

Which of the following best explains why gases are compressible but solids and liquids are not?

Accepted Answer

Gases have particles that are far apart, allowing them to be compressed.

Question 6

Which of the following is an example of a homogeneous mixture?

Accepted Answer

Salt water

Question 7

Which law states that matter cannot be created or destroyed in a chemical reaction?

Accepted Answer

Law of Conservation of Mass

Question 8

A sample of water is heated from $$25\ ^\circ\mathrm{C} to$$ $$75\ ^\circ\mathrm{C}. If $$the mass of the water is $$100\ \mathrm{g}$$ and the specific heat capacity is $$4.18\ \mathrm{J/g\ ^\circ C}$$, how much heat is absorbed?

Accepted Answer

$$q = 100 	imes 4.18 	imes (75 - 25) = 20,900\ \mathrm{J}$$

Question 9

Which of the following is a chemical property?

Accepted Answer

Reactivity with acid

Question 10

Which of the following is a sign that a chemical change has occurred?

Accepted Answer

A gas is produced when two substances are mixed.

Question 11

Which of the following best describes the difference between mass and weight?

Accepted Answer

Mass is the amount of matter in an object; weight is the force of gravity on that object.

Question 12

Which of the following is NOT a pure substance?

Accepted Answer

Air

Question 13

A student needs to separate a mixture of sand, salt, and iron filings. Which sequence of separation methods should be used?

Accepted Answer

Use a magnet, then dissolve in water, then filter.

Question 14

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

Accepted Answer

Melting ice

Question 15

Which of the following best describes an exothermic process?

Accepted Answer

The system releases heat and the surroundings get warmer.

Question 16

Convert $$25\ ^\circ\mathrm{C} to $$Kelvin.

Accepted Answer

$$25 + 273.15 = 298.15\ \mathrm{K}$$

Question 17

Which of the following is a heterogeneous mixture?

Accepted Answer

Salad dressing with oil and vinegar

Question 18

Which of the following is NOT a sign of a chemical change?

Accepted Answer

Melting of ice

Question 19

Which of the following best describes the process of distillation?

Accepted Answer

Separating substances based on differences in boiling points.

Question 20

A student mixes two colorless solutions and observes the formation of a yellow solid. What is the best explanation for this observation?

Accepted Answer

A chemical change occurred, forming a precipitate.

Matter and Energy: Foundations of Chemistry

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