Chapter 7.2, Problem 1RQ

(a)

Interpretation Introduction

Interpretation :

Reactants and products must be identified along with chemical equation when silicon is produced along with carbon dioxide from silicon dioxide and carbon.

Concept Introduction :

Carbon is a reducing agent which reduces silicon dioxide to silicon and itself oxidized to carbon dioxide.

Answer to Problem 1RQ

The reactants are silicon dioxide (SiO₂) and carbon (C). Products are silicon (Si) and carbon dioxide (CO₂).

Explanation of Solution

The chemical reaction is represented as follows:

  ${\text{SiO}}_{\text{2}}\text{(s)+C(s)}\to {\text{Si(s)+CO}}_{\text{2}}\text{(g)}\text{.}$

From the reaction it is clear that solid Si is produced by reduction of SiO₂ with C. C is oxidized to CO₂.

b)

Interpretation Introduction

Interpretation :

Reactants and products must be identified along with chemical equation when ammonium chloride is heated with sodium hydroxide to produce ammonia gas water vapor and sodium chloride.

Concept Introduction :

Any ammonium salt when heated with alkali produces ammonia gas, salt and water vapor.

Answer to Problem 1RQ

The reactants are ammonium chloride (NH₄Cl) and sodium hydroxide (NaOH). Products are ammonia (NH₃), water vapor (H₂O) and sodium chloride (NaCl).

Explanation of Solution

  ${\text{NH}}_{\text{4}}\text{Cl(s)+NaOH(aq)}\to {\text{NH}}_{\text{3}}{\text{(g)+H}}_{\text{2}}\text{O(l)+NaCl(s)}\text{.}$

From the reaction it is clear that ammonia (NH₃) water vapor (H₂O) and sodium chloride (NaCl) are produced from ammonium chloride (NH₄Cl) and sodium hydroxide (NaOH).

c)

Interpretation Introduction

Interpretation :

Reactants and products must be identified along with chemical equation when calcium oxide absorbs moister from air to produce calcium hydroxide.

Concept Introduction :

Calcium oxide is base which can produce alkali after dissolving in water.

Answer to Problem 1RQ

The reactants are calcium oxide (CaO) and water (H₂O). Products is calcium hydroxide

Ca (OH) ₂.

Explanation of Solution

  ${\text{CaO(s)+H}}_{\text{2}}\text{O(l)}\to {\text{Ca(OH)}}_{\text{2}}\text{(aq)}\text{.}$

From the reaction it is clear that solid calcium oxide (CaO) absorbs water vapor (H₂O) and produces calcium hydroxide Ca (OH) ₂ after dissolving in the water. CaO is very much hygroscopic.