Q: A 50.0 g sample of metal absorbs 480 J of heat, and its temperature increases from 20.0 $$^\circC to 35.0$$ $$^\circC. $$What is the specific heat capacity $$c of $$the metal?

$$c = \dfrac{480}{50.0 \times (35.0 - 20.0)} = 0.64 \ \mathrm{J/g}^\circ\mathrm{C}$$

Q: Which formula correctly expresses the relationship for calculating heat absorbed or released by a substance?

$$q = m \times c \times \Delta T$$

Question 1

Which of the following best describes the two essential properties that all matter must possess?

Accepted Answer

Mass and volume

Question 2

Which statement correctly differentiates between a physical change and a chemical change at the molecular level?

Accepted Answer

Chemical changes involve the rearrangement of atoms to form new substances, while physical changes do not affect the chemical identity.

Question 3

Which of the following is a pure substance?

Accepted Answer

Gold (Au)

Question 4

Classify NaCl (table salt) as an element or a compound.

Accepted Answer

Compound

Question 5

Which of the following is a chemical property?

Accepted Answer

Ability to react with acid

Question 6

A sample of matter is uniform throughout and can be separated by physical means. Which type of mixture is this?

Accepted Answer

Homogeneous mixture

Question 7

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

Accepted Answer

Burning a candle

Question 8

According to the Law of Conservation of Mass, which equation correctly represents the relationship between the mass of reactants and products in a chemical reaction?

Accepted Answer

$$m_\mathrm{reactants} = m_\mathrm{products}$$

Question 9

If 8.0 g of oxygen gas reacts completely with 8.0 g of magnesium to produce magnesium oxide, what is the expected mass (in grams) of the magnesium oxide product?

Accepted Answer

16.0 g

Question 10

Why does water condensing on a cold glass of soda feel warm to the touch, and is this process exothermic or endothermic?

Accepted Answer

It releases heat to your hand; exothermic

Question 11

Convert 25 $$^\circC ($$room temperature) to the Kelvin scale.

Accepted Answer

$$K = 25 + 273.15 = 298.15$$

Question 12

The boiling point of liquid nitrogen is 77 K. What is this temperature in Celsius?

Accepted Answer

$$^\circ\mathrm{C} = 77 - 273.15 = -196.15$$

Question 13

Explain why the specific heat capacity of water is much higher than that of most metals.

Accepted Answer

Water molecules have strong hydrogen bonds that require more energy to increase temperature.

Question 14

A 50.0 g sample of metal absorbs 480 J of heat, and its temperature increases from 20.0 $$^\circC to 35.0$$ $$^\circC. $$What is the specific heat capacity $$c of $$the metal?

Accepted Answer

$$c = \dfrac{480}{50.0 	imes (35.0 - 20.0)} = 0.64 \ \mathrm{J/g}^\circ\mathrm{C}$$

Question 15

Which of the following is a heterogeneous mixture?

Accepted Answer

A banana

Question 16

Which of the following is NOT a chemical change?

Accepted Answer

Dissolving sugar in water

Question 17

Which of the following is a physical property?

Accepted Answer

Boiling point

Question 18

Which of the following is a valid chemical indication that a chemical reaction has occurred?

Accepted Answer

Formation of a precipitate

Question 19

Which formula correctly expresses the relationship for calculating heat absorbed or released by a substance?

Accepted Answer

$$q = m 	imes c 	imes \Delta T$$

Question 20

Which of the following best defines temperature in terms of atomic and molecular motion?

Accepted Answer

Temperature is a measure of the average kinetic energy of the particles.

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