Chapter U4, Problem SI3RE

(a)

Interpretation Introduction

Interpretation:

The chemical equation for formation of kidney stones is given. The nature of each reactant as ionic or covalent has to be explained.

Concept Introduction :

An ionic bond is formed by complete transfer of electron from one species to other. A covalent bond is formed by sharing of electrons between two elements.

Answer to Problem SI3RE

The given reactants are ionic as ions involved in ${\text{Na}}_{\text{3}}{\text{PO}}_{\text{4}}$ are ${\text{Na}}^{\text{+}}$ and ${\text{PO}}_{\text{4}}{}^{3-}$ . The ions involved in ${\text{CaCl}}_{\text{2}}$ are ${\text{Ca}}^{\text{2+}}$ and ${\text{Cl}}^{-}$ .

Explanation of Solution

The given reactant ${\text{Na}}_{\text{3}}{\text{PO}}_{\text{4}}$ and ${\text{CaCl}}_{\text{2}}$ is ionic. The ions involved in ${\text{Na}}_{\text{3}}{\text{PO}}_{\text{4}}$ are ${\text{Na}}^{\text{+}}$ and ${\text{PO}}_{\text{4}}{}^{3-}$ . The ions involved in ${\text{CaCl}}_{\text{2}}$ are ${\text{Ca}}^{\text{2+}}$ and ${\text{Cl}}^{-}$ . Thus, the electrostatic force of attraction between these ions generates the ionic compounds.

(b)

Interpretation Introduction

Interpretation:

The nature of given reaction as combination reaction, decomposition reaction, single exchange or double exchange reaction has to be predicted.

Concept Introduction :

The double exchange reaction involves exchange of ions between two different compounds.

Answer to Problem SI3RE

The given chemical equation is double exchange reaction.

Explanation of Solution

The given reactant are ${\text{Na}}_{\text{3}}{\text{PO}}_{\text{4}}$ and ${\text{CaCl}}_{\text{2}}$ . The ions involved in ${\text{Na}}_{\text{3}}{\text{PO}}_{\text{4}}$ are ${\text{Na}}^{\text{+}}$ and ${\text{PO}}_{\text{4}}{}^{3-}$ . The ions involved in ${\text{CaCl}}_{\text{2}}$ are ${\text{Ca}}^{\text{2+}}$ and ${\text{Cl}}^{-}$ . The products formed are ${\text{Ca}}_{\text{3}}{\left({\text{PO}}_{\text{4}}\right)}_{\text{2}}$ and $\text{NaCl}$ . Thus, phosphate ions are shown to combine with calcium and chloride ions are shown to combine with sodium. Thus, here two exchanges of ions has taken place. Thus, it is a double exchange reaction.

(c)

Interpretation Introduction

Interpretation:

The nature of given reaction as chemical or physical change has to be predicted.

Concept Introduction :

A physical change does not lead to the formation of any new substance while a chemical change generates a new substance.

Answer to Problem SI3RE

The given reaction is a chemical change.

Explanation of Solution

In the given reaction two reactants have combined to give totally different products. Thus, the given reaction is identified as a chemical change. The reactants that have undergone reaction are sodium phosphate and calcium chloride while the products formed are calcium phosphate and sodium chloride.

(d)

Interpretation Introduction

Interpretation:

The importance of balancing of chemical equation for the conservation of matter has to be explained.

Concept Introduction:

Balancing of chemical equation involves equalizing the number of atoms of each element on both the sides of the chemical equation.

Answer to Problem SI3RE

Balancing of chemical equation leads to the conservation of mass that ultimately shows the conservation of matter.

Explanation of Solution

Matter cannot undergo formation or destruction. The law of conservation of mass has to be followed. According to this the mass of the reactants undergoing chemical reaction is equivalent to the products formed as a result of chemical reaction. Thus, on balancing the chemical equation the number of atoms of each element becomes equal on both the sides of the equation. This ultimately balances the mass on both the sides of the equation.

(e)

Interpretation Introduction

Interpretation:

The chemical name of solid that makes up kidney stones is to be stated.

Concept Introduction:

When an ionic compound is named, the name of cation is written first followed by the name of anion.

Answer to Problem SI3RE

The chemical name of solid that makes up kidney stones is calcium phosphate.

Explanation of Solution

Majorly calcium oxalate is responsible for kidney stones. But calcium phosphate also acts as a minor contributor in the kidney stones In the given equation, calcium phosphate solid is the chemical compound that causes kidney stones. Its formula has been given as ${\text{Ca}}_{\text{3}}{\left({\text{PO}}_{\text{4}}\right)}_{\text{2}}$ .