Deck 10: Chemical Reactions

Question 1

The reaction: 2 NaI + Cl₂ $\rarr$ 2 NaCl + I₂ is an example of

A)decomposition.
B)combination.
C)replacement.
D)ion exchange.

Answer 1

replacement.

Question 2

What is the formula weight of methane, CH₄?

A)13 u
B)16 u
C)52 u
D)None of the above.

Answer 2

B

Question 3

When the equation __Li + __O₂ $\rarr$ __Li₂O is correctly balanced, what is the sum of the coefficients?

A)3
B)5
C)7
D)12

Answer 3

7

Question 4

The reaction: potassium chlorate potassium chloride and oxygen gas is an example of

A)decomposition.
B)combination.
C)replacement.
D)ion exchange.

Question 5

The sum of the coefficients must be the same on both sides of a chemical equation.

Question 6

In a chemical equation, the reactants are found on the left side of the arrow.

Question 7

In combination reactions, elements react to form compounds.

Question 8

The reaction 2 M_g + O₂ $\rarr$ 2 M_gO is an example of

A)oxidation.
B)combination.
C)combustion.
D)All of the above.

Question 9

When balancing a chemical equation, you need to change subscripts to make the number of atoms of an element the same on both sides of the equation.

Question 10

When balancing a chemical equation, the number of H atoms in 2 CH₄ is eight.

Question 11

What is the number of oxygen atoms in Al₂(SO₄)₃?

A)3
B)4
C)7
D)12

Question 12

What is the number of atoms on each side of the equation?

A)5
B)6
C)7
D)9

Question 13

When compounds containing carbon and hydrogen are burned in air, the products are usually carbon dioxide and water.

Question 14

What is the empirical formula of C₄H₈?

A)CH
B)CH₂
C)C₄H₈
D)C₂H₄

Question 15

A chemical reaction is balanced by changing (the)

A)subscripts.
B)superscripts.
C)coefficients.
D)Any of the above as needed.

Question 16

Chemists effectively count atoms by weighing matter.

Question 17

Substances that lose electrons in reactions are called oxidizing agents.

Question 18

The empirical formula gives the actual number of atoms of each kind in a compound.

Question 19

What is the total mass of products in the methane reaction shown before question 11?

A)80 u
B)64 u
C)62 u
D)48 u

Question 20

A decomposition reaction always breaks down a compound into the elements that make up the compound.

Question 21

What is the formula weight of aluminum hydroxide, Al(OH)₃?

A)44 u
B)45 u
C)75 u
D)78 u

Question 22

The reaction between water solutions of sodium chloride and silver nitrate produces a precipitate: NaCl_(aq) + AgNO_3(aq) $\rarr$ NaNO_3(aq) + AgCl_(s).This is an example of

A)decomposition.
B)combination.
C)replacement.
D)ion exchange.

Question 23

What is the mass of 0.50 mole of baking soda, N_aHCO₃?

A)26 g
B)42 g
C)84 g
D)168 g

Question 24

Because of our belief in the law of conservation of mass, it seems reasonable that

A)in combustion reactions, part of the mass of the reactants must be converted into fire.
B)the mass of a newly formed compound cannot be changed.
C)molecules cannot be broken down, for the mass would be reduced.
D)the number of atoms of reactants must equal the number of atoms of products.

Question 25

How many molecules are in a 8.0-g sample of oxygen gas, O₂?

A)6.0 * 10²³
B)3.0 * 10²³
C)1.5 * 10²³
D)12.0 * 10²³

Question 26

What is the mass percent of sodium in washing soda, Na₂CO₃?

A)43.4%
B)32.5%
C)21.7%
D)62.1%

Question 27

What is the total number of atoms in calcium phosphate, Ca₃(PO₄)₂?

A)8
B)9
C)11
D)13

Question 28

Which of the following is a sign of an ion exchange reaction?

A)a precipitate is formed
B)a compound is broken down into simpler substances
C)a reactant is oxidized
D)a metal ion is reduced

Question 29

An oxidizing agent is a substance that

A)reacts with oxygen.
B)removes electrons from another substance.
C)supplies electrons to another substance.
D)frees a metal from its ore.

Question 30

The equation 2 C₂H₅OH + __O₂ $\rarr$ 4 CO₂ + 6 H₂O is balanced by making the coefficient of oxygen

A)14.
B)12.
C)7.
D)6.