Question 1

Which of the following best describes the Law of Conservation of Mass as discovered by Antoine Lavoisier?

Accepted Answer

The total mass of substances before and after a chemical reaction is always equal.

Question 2

The term 'atom' comes from the Greek word 'atomos.' What does 'atomos' mean?

Accepted Answer

cannot be cut

Question 3

A log burns in a campfire, leaving much less mass in the ashes than the original log. According to the Law of Conservation of Mass, what happened to the matter?

Accepted Answer

The matter that composed the log reacts to form gases that are released into the air.

Question 4

After a 10 g sample of lithium metal reacts in a closed container with 44.32 g of chlorine gas, 1.32 g of lithium remains and the chlorine is consumed completely. What mass of lithium chloride is formed?

Accepted Answer

54.32 g

Question 5

Which postulate of Dalton’s Atomic Theory explains why the mass of reactants equals the mass of products in a chemical reaction?

Accepted Answer

Atoms of an element are not changed into atoms of a different element by chemical reactions; atoms are neither created nor destroyed in chemical reactions.

Question 6

Which chemical law is illustrated when two samples of carbon monoxide are decomposed and both show the same ratio of oxygen to carbon?

Accepted Answer

Law of Definite Proportions

Question 7

Nitrogen dioxide contains 2.28 g oxygen per 1.00 g nitrogen, while dinitrogen monoxide contains 0.570 g oxygen per 1.00 g nitrogen. What law do these results illustrate?

Accepted Answer

Law of Multiple Proportions

Question 8

Which statement best captures the difference between the law of definite proportions and the law of multiple proportions?

Accepted Answer

The law of definite proportions applies to two or more samples of the same compound, while the law of multiple proportions applies to two different compounds containing the same two elements.

Question 9

In his early periodic table, Mendeleev arranged the known elements into groups primarily according to what criterion?

Accepted Answer

Similar chemical properties

Question 10

Avogadro’s number is used to convert between particles and moles. What is Avogadro’s number?

Accepted Answer

$$6.02 	imes 10$$^{23}$$

Question 11

How many moles of $$CO_2$$ are in $$2.50 	imes 10$$^{24}$$ molecules of CO_2$?

Accepted Answer

$$4.15$$ moles

Question 12

What is the mass of $$1.33$$ moles of titanium ($$Ti$$), given the molar mass of $$Ti is$$ $$47.88 g/$$mol?

Accepted Answer

$$63.7 g$$

Question 13

What is the mass of $$2.55 	imes 10$$^{23}$$ atoms of lead (Pb$), given the molar mass of Pb$ is 207.2$ g/mol?

Accepted Answer

$$87.9 g$$

Question 14

If a pure copper penny has $$2.81 	imes 10$$^{22}$$ atoms, what will be its mass? (Molar mass of Cu = 63.55$ g/mol)

Accepted Answer

$$2.97 g$$

Question 15

Which has more atoms: $$10.0 g of Mg or$$ $$10.0 g of Ca$$?

Accepted Answer

Magnesium

Question 16

Which of the following has the largest mass?

Accepted Answer

10.0 mol Rb

Question 17

How many moles of carbon dioxide are represented by $$150.0 g of$$ $$CO_2$$? (Molar mass of $$CO_2$$ = $$44.0 g/$$mol)

Accepted Answer

$$3.41$$ moles

Question 18

What is the mass, in grams, of $$3.25$$ moles of ammonia ($$NH_3$$)? (Molar mass of $$NH_3$$ = $$17.03 g/$$mol)

Accepted Answer

$$55.3 g$$

Question 19

Isotopes have:

Accepted Answer

the same number of protons, but different numbers of neutrons.

Atoms, Atomic Theory, and the Periodic Table: Study Notes for Introductory Chemistry

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