Chapter U4.70, Problem 6E

(a)

Interpretation Introduction

Interpretation:

Reaction of calcium carbonate and sulfuric acid must be classified as physical or chemical change with reason.

Concept Introduction :

In chemical change, new substances are generated which have different physical and chemical properties. In physical change, the appearance of the substances change keeping the chemical properties same.

Answer to Problem 6E

Reaction of calcium carbonate and sulfuric acid is a chemical change.

Explanation of Solution

The reaction is represented as follows:

  $CaC{O}_3\left(s\right)+H_{2}S{O}_4\left(aq\right)\to CaS{O}_4\left(aq\right)+C{O}_2\left(g\right)+H_{2}O\left(l\right)$

In this reaction, new substances like calcium sulfate, carbon dioxide and water are generated from calcium carbonate and sulfuric acid. Thus, it is a chemical change.

(b)

Interpretation Introduction

Interpretation:

Melting of sodium chloride must be classified as physical or chemical change with reason.

Concept Introduction :

In chemical change new substances are generated which have different physical and chemical properties. In physical change, the appearance of the substances change keeping the chemical properties same.

Answer to Problem 6E

Melting of sodium chloride is a physical change.

Explanation of Solution

In melting of a solid, the intermolecular force is reduced and intermolecular distance is increased due to addition of thermal energy. Arrangements of atoms are changed. The lattice of NaCl(s) is broken. In this case, no chemical properties of NaCl are changed. Thus, it is a physical change.