Chapter 18, Problem 18.120MP

(a)

Interpretation Introduction

Interpretation:

The balanced equation for reaction of ${\text{PH}}_{\text{3}}$ with Oxygen to form Phosphoric acid has to be written.

Concept Introduction:

• There is a law for conversion of mass in a chemical reaction i.e., the mass of total amount of the product should be equal to the total mass of the reactants.
• The concept of writing a balanced chemical reaction is depends on conversion of reactants into products.
• First write the reaction from the given information.
• Then count the number of atoms of each element in reactants as well as products.
• Finally necessary values could be placed as coefficients of reactants as well as products to obtain a balanced equation.

(b)

Interpretation Introduction

Interpretation:

The $\text{pH}$ of given Phosphoric acid solution has to be determined.

Concept Introduction:

$\text{pH}$ definition:

The concentration of hydrogen ion is measured using $\text{pH}$ scale.  The acidity of aqueous solution is expressed by $\text{pH}$ scale.

The $\text{pH}$ of a solution is defined as the negative logarithm of concentration of hydrogen ion or hydronium ion.

$\text{pH}\text{=}{\text{-log[H}}_{\text{3}}{\text{O}}^{\text{+}}\text{]}$

On rearranging the above equation, the concentration of hydrogen ion ${\text{[H}}^{+}\text{]}$ can be calculated using $\text{pH}$ as follows,

${\text{[H}}^{+}\text{]}\text{=}{\text{10}}^{\text{-pH}}$