Chapter U4, Problem 1RE

(a)

Interpretation Introduction

Interpretation: The given equation between zinc and aqueous HCl needs to be balanced.

Concept Introduction:

The chemical reaction must be balanced such that it agrees with the law of mass conservation. A balanced chemical equation arises when the number of atoms or ions of the reactant side is equal to the number of atoms or ions of the product side.

Answer to Problem 1RE

  $\text{Zn(s) + 2HCl(aq) }\to {\text{ ZnCl}}_{\text{2}}(aq){\text{ + H}}_{\text{2}}(g)$

Explanation of Solution

When the reaction of zinc metal (Zn) with aqueous hydrochloric (HCl) takes place, it gives an aqueous solution of zinc chloride (ZnCl₂) and hydrogen (H₂) gas.

The unbalanced reaction is as follows:

  $\text{Zn(s) + HCl(aq) }\to {\text{ ZnCl}}_{\text{2}}(aq){\text{ + H}}_{\text{2}}(g)$

It can be balanced by giving coefficient 2 to HCl.

Thus, the balanced reaction is as follows:

  $\text{Zn(s) + 2HCl(aq) }\to {\text{ ZnCl}}_{\text{2}}(aq){\text{ + H}}_{\text{2}}(g)$

(b)

Interpretation Introduction

Interpretation: The given equation for the decomposition of potassium chlorate needs to be balanced.

Concept Introduction:

The chemical reaction must be balanced such that it agrees with the law of mass conservation. A balanced chemical equation arises when the number of atoms or ions of the reactant side is equal to the number of atoms or ions of the product side.

Answer to Problem 1RE

  ${\text{2KClO}}_{\text{3}}\text{(s) }\to \text{ 2KCl}(\text{s}){\text{ + 3O}}_{\text{2}}(g)$

Explanation of Solution

The decompositions of solid potassium chlorate KClO₃ give potassium chloride in solid form and oxygen gas.

Unbalance reaction:

  ${\text{KClO}}_{\text{3}}\text{(s) }\to \text{ KCl}(\text{s}){\text{ + O}}_{\text{2}}(g)$

The above reaction can be balanced by giving coefficient 2 to ${\text{KClO}}_{\text{3}}$ , 2 to KCl and 3 to oxygen gas.

Thus,

Balanced reaction:

  ${\text{2KClO}}_{\text{3}}\text{(s) }\to \text{ 2KCl}(\text{s}){\text{ + 3O}}_{\text{2}}(g)$

(c)

Interpretation Introduction

Interpretation: The given equation between solid sulfur and fluorine gas needs to be balanced.

Concept Introduction:

The chemical reaction must be balanced such that it agrees with the law of mass conservation. A balanced chemical equation arises when the number of atoms or ions of the reactant side is equal to the number of atoms or ions of the product side.

Answer to Problem 1RE

  ${\text{S}}_{\text{8}}{\text{(s) + 24F}}_{\text{2}}\text{(g) }\to {\text{ 8SF}}_{\text{6}}\text{(g)}$

Explanation of Solution

When solid sulfur treats with fluorine gas, it gives sulfur hexafluoride in gaseous form.

Unbalance reaction;

  ${\text{S}}_{\text{8}}{\text{(s) + F}}_{\text{2}}\text{(g) }\to {\text{ SF}}_{\text{6}}\text{(g)}$

To balance the above reaction give coefficient 24 to F₂ and 8 to SF₆.

Thus,

Balanced reaction;

  ${\text{S}}_{\text{8}}{\text{(s) + 24F}}_{\text{2}}\text{(g) }\to {\text{ 8SF}}_{\text{6}}\text{(g)}$

(d)

Interpretation Introduction

Interpretation: The given equation between iron metal and oxygen gas needs to be balanced.

Concept Introduction:

The chemical reaction must be balanced such that it agrees with the law of mass conservation. A balanced chemical equation arises when the number of atoms or ions of reactant side are equals to the number of atom or ions of product side.

Answer to Problem 1RE

  ${\text{4Fe(s) + 3O}}_{\text{2}}\text{(g) }\to {\text{ 2Fe}}_2{\text{O}}_{\text{3}}\text{(s)}$

Explanation of Solution

Iron metal reacts with oxygen gas to give solid ferric oxide (Fe₂O₃).

Unbalance reaction;

  ${\text{Fe(s) + O}}_{\text{2}}\text{(g) }\to {\text{ Fe}}_2{\text{O}}_{\text{3}}\text{(s)}$

The above reaction can be balanced by giving coefficient 4 to Fe, 3 to oxygen gas and 2 to ferric oxide.

Balanced reaction:

  ${\text{4Fe(s) + 3O}}_{\text{2}}\text{(g) }\to {\text{ 2Fe}}_2{\text{O}}_{\text{3}}\text{(s)}$