R-1 Reactions

Question 1

Identify the following type of reaction

AB ⇒ A + B

Answer 1

Decomposition

Question 2

Identify the following type of reaction

AB + C ⇒ AC + B

Answer 2

Single Replacement

Question 3

Identify the following type of reaction

AB (aq) + CD (aq) ⇒ AD (s) + CB (aq)

Answer 3

Double Replacement or metathesis that forms a precipitate

Question 4

Identify the following type of reaction

AOH (aq) + HB (aq) ⇒ AB (aq) + H₂O (l)

Answer 4

Double Replacement or metathesis-neutralization

Question 5

Identify the following type of reaction

A + B ⇒ AB

Answer 5

Synthesis

Question 6

Identify the following type of reaction

C_xH_y + O₂ ⇒ CO₂ + H₂O

Answer 6

Combustion of a hydrocarbon

Question 7

Identify the following type of reaction

2 NaO (s) + H₂O (l) ⇒ 2 NaOH (aq)

Answer 7

Synthesis but also a metal oxide in water

Question 8

Identify the following type of reaction

SO₃ (g) + H₂O (l) ⇒ H₂SO₄ (aq)

Answer 8

Synthesis but also a non metal oxide in water.

Notice: The sulfur has a +6 oxidation number as a reactant and a product.

Question 9

Identify the following type of reaction

Na₂SO₃ (aq) + 2 HCl (aq) ⇒ 2 NaCl (aq) + SO₂ (g) + H₂O (l)

Answer 9

Metathesis reaction that produces a gas

Note: Carbonate/bicarbonates with an acid make CO₂ and H₂O

Note: Sulfites and an acid make SO₂ and H₂O

Note: Ammonium ions and hydroxide makes NH₃ and H₂O

Question 10

Identify the following type of reaction

2 NaCl (aq) + F₂ (g) ⇒ 2 NaF (aq) + Cl₂ (g)

Answer 10

Single Replacement (anionic)

Question 11

Identify the following type of reaction

NaCl (aq) + Li (s) ⇒ Na (s) + LiCl (g)

Answer 11

Single Replacement (cationic)

Question 12

Identify the following type of reaction

Li₂SO₄ (aq) + Pb(NO₃)₂ (aq) ⇒ 2 LiNO₃ + PbSO₄ (s)

Answer 12

Double Replacement (Precipitation)

Question 13

Identify the following type of reaction

C (s) + O₂ (g) ⇒ CO₂ (g)

Answer 13

Synthesis

Question 14

Identify the following type of reaction

2 CaO (s) ⇒ 2 Ca (s) + O₂ (g)

Answer 14

Decomposition

Question 15

Identify the following type of reaction

2 C₂H₂ (g) + 5 O₂ (g) ⇒ 4 CO₂ (g) + 2 H₂O (g)

Answer 15

Combustion of a hydrocarbon

Question 16

What is wrong with the way the following reaction is written?

4 H₂ (g) + 2 O₂ (g) ⇒ 4 H₂O (l)

Answer 16

Reactions are written in lowest whole number form

2 H₂ (g) + O₂ (g) ⇒ 2 H₂O (l)

Question 17

What is wrong with the way the following reaction is written?

2 KBr (aq) + Cl₂ (g) ⇒ 2 KCl (aq) + 2Br (l)

Answer 17

Bromine is diatomic

Question 18

What is wrong with the way the following reaction is written?

2 KBr (aq) + Cl₂ (g) ⇒ 2 K (s) + 2 BrCl (aq)

Answer 18

This is anionic single replacement so the anion switch places. The K combines with the Cl.

Question 19

What is wrong with the way the following reaction is written?

3 CuCl₂ (aq) + 2 Al³⁺ (s) ⇒ 2 AlCl₃ (aq) + 3 Cu^{<span>2+</span>} (s)

Answer 19

Metals do not have a charge unless they dissociated. Both the elemental forms of Cu and the Al do not have a charge.

Question 20

What is wrong with the way the following reaction is written?

CH₄ (g) + O₂ (g) ⇒ CO₂ (g) + 2 H₂ (g)

Answer 20

This is combustion of a hydrocarbon reaction, not a single replacement reaction.

Question 21

What is wrong with the way the following reaction is written?

2 NaCl (aq) + Pb(NO₃)₂ (aq) ⇒ 2 NaNO₃ (aq) + PbCl (s)

Answer 21

The reaction is not balanced and the charge of of the lead ion needs to be +2 in the lead chloride since it is +2 in the lead (II) nitrate in the reactants.

Question 22

What is wrong with the way the following reaction is written?

NaCl (aq) + AgNO₃ (aq) ⇒ NaAg (s) + ClNO₃ (aq)

Answer 22

The positive silver ion should combine with the negative chloride ion to form a precipitate and the positive sodium ion should combine with the negative nitrate ion.

Question 23

What is wrong with the way the following reaction is written?

SO₂ (g) + H₂0 (l) ⇒ H₂SO₄ (aq)

Answer 23

The reaction is not balanced and the oxidation number of the sulfur atom in the reactants is +4 while it is +6 in the products. The oxidation number should be the same for a nonmetal oxide in water so the product should be H₂SO₃ (aq)

Question 24

What is wrong with the way the following reaction is written?

CaO (s) + H₂O (l) ⇒ CaH₂ (aq) + O₂ (g)

Answer 24

This is a metal oxide in water so the product should be a hydroxide, Ca(OH)₂,

Question 25

What is wrong with the way the following reaction is written?

MgCO₃ (s) + 2 HCl (aq) ⇒ MgCl₂ (aq) + H₂CO₃ (aq)

Answer 25

Carbonates and an acid will form CO₂ and H₂O so the products should be MgCl₂ + CO₂ + H₂O.

Note: Bicarbonates and acis do the same thing

Note: Sulfites and acids become SO₂ and H₂O.

Note: Ammonium ion and hydroxide becomes ammonia and water

Question 26

What is wrong with the way the following reaction is written?

3 Ag (s) + N (g) ⇒ Ag₃N (s)

Answer 26

Nitrogen gas is diatomic so it should be written as N₂

Question 27

What is wrong with the way the following reaction is written?

2 AlO (s) ⇒ 2 Al (s) + O₂ (g)

Answer 27

AlO should be Al₂O₃ since Al has a +3 charge and O has a -2 charge.