Question 1

A laboratory technician observes a sample of matter with particles arranged in a fixed, repeating three-dimensional pattern. Which classification best describes this sample?

Accepted Answer

Crystalline solid

Question 2

Which of the following is an example of a pure element?

Accepted Answer

Pure gaseous helium in a balloon

Question 3

When magnesium metal burns in air, it produces a white powder. This is an example of:

Accepted Answer

A chemical change

Question 4

A chemist observes that a liquid forms two distinct layers after standing. This system is best described as:

Accepted Answer

A heterogeneous mixture

Question 5

The statement, "The boiling point of liquid nitrogen is 77 Kelvin," describes:

Accepted Answer

A physical property

Question 6

A nutrition label states that a snack bar contains 180. Calories (Cal). How many joules (J) of energy does this represent? (1 Cal = 1000 cal, 1 cal = 4.184 J)

Accepted Answer

$$7.53 	imes 10^5$ J

Question 7

A chemical reaction in an insulated vessel causes the temperature of the surroundings to decrease. This process is best classified as:

Accepted Answer

An endothermic chemical reaction

Question 8

An industrial oven reads 482 $$^\circF. $$What is this temperature in Celsius?

Accepted Answer

$$232\ ^\circ\mathrm{C}$$

Question 9

If 24.3 grams of magnesium react completely with 16.0 grams of oxygen, what is the total mass of magnesium oxide produced, according to the Law of Conservation of Mass?

Accepted Answer

$$40.3$$ grams

Question 10

Equal 50.0-gram samples of iron ($$C = 0.449 J/g$\cdot ^\circC) $$and aluminum ($$C = 0.903 J/g$\cdot ^\circC) $$are each heated with 500. J of energy. Which statement is correct?

Accepted Answer

The iron sample will experience a larger increase in temperature because it has a lower specific heat capacity.

Question 11

A 250.0-gram sample of a liquid ($$C = 1.85 J/g$\cdot ^\circC) $$absorbs $$4,625 J of $$energy. What is the temperature change $$\Delta T$$? Use $$q = mC\Delta T.$$

Accepted Answer

$$10.0\ ^\circ\mathrm{C}$$

Question 12

A jeweler heats a 15.5-gram gold ring from $$22.0\ ^\circC to$$ $$145.0\ ^\circC. $$Gold's specific heat is $$C = 0.128 J/g$\cdot ^\circC. $$How much heat energy is required?

Accepted Answer

$$246 J$$

Question 13

A blacksmith drops an 85.0-gram copper block ($$C = 0.385 J/g$\cdot ^\circC) $$into 200.0 grams of water ($$C = 4.184 J/g$\cdot ^\circC). $$The water's temperature rises by $$4.50\ ^\circC. $$What is the temperature change $$\Delta T of $$the copper? (Assume no heat loss.)

Accepted Answer

$$-49.5\ ^\circ\mathrm{C}$$

Question 14

A laboratory hotplate uses $$1.45$$ kWh of energy. Convert this to joules (J). ($$1$$ kWh $$= 3.60 	imes 10^6$ J)

Accepted Answer

$$5.22 	imes 10^6$ J

Question 15

Liquid helium liquefies at $$4.20 K. $$What is this temperature in $$^\circC$$? (Use $$^\circC$$ $$= K - 273.15)$$

Accepted Answer

$$-268.95\ ^\circ\mathrm{C}$$

Question 16

Which of the following best describes the difference between temperature and heat?

Accepted Answer

Temperature measures the average kinetic energy of particles, while heat is the transfer of energy due to a temperature difference.

Question 17

A technician seals 12.0 g of carbon and 32.0 g of oxygen in a rigid container and ignites them to form carbon dioxide. What is the total mass inside the container after the reaction, and which law explains this?

Accepted Answer

44.0 g; Law of Conservation of Mass

Question 18

Which of the following is a correct classification for the given substance: completely dissolved saline solution (saltwater)?

Accepted Answer

Homogeneous mixture

Question 19

A heavy metal weight is dropped from a rooftop. Which sequence best describes the energy transformations as it falls and hits the ground?

Accepted Answer

Potential energy $$\rightarrow$$ kinetic energy $$\rightarrow$$ thermal energy

Chapter 3: Matter and Energy – Guided Chemistry Study Notes

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