Question

The normality of $10\% \left( {w/v} \right)$ of acetic acid is:
A. $1N$
B. $1.3N$
C. $1.7N$
D. $1.9N$

Answer 1

Normality is defined as the measure of the concentration of a solution. Normality is expressed as the number of gram equivalents of the solute per litre of the solution.

Complete step by step answer:
Acetic acid is an organic carboxylic acid. It contains a methyl group attached o a carboxyl group. The chemical formula of acetic acid is $C{H_3}COOH$ . The commercial glacial acetic acid is around $17N$. The molar mass of acetic acid = $2{\text{ }} \times$ atomic mass of $C$ + $4{\text{ }} \times$ atomic mass of $H$ + $2{\text{ }} \times$ atomic mass of $O$.
$= 2 \times 12 + 4 \times 1 + 2 \times 16 = 60g/mol.$
The key points related to Normality are:
a. It is also known as equivalent concentration of the solute in solution.
b. It is the ratio of the number of grams equivalent of the solute per litre of the solution.
c. It is also used to determine the gram equivalent of the solute for a total volume of a solution.
d. It is abbreviated as $N$ and has the units of$eq{L^{ - 1}}$.
The given solution is a $10\% \left( {w/v} \right)$ acetic acid solution. The percentage indicates that $10g$ of acetic acid is dissolved in$100mL$ of water. The amount of acetic acid present in $1000mL$ or $1L$ of water =$10 \times 10 = 100g$.
The molar mass of acetic acid is $60g/mol$, i.e. $60g$ of acetic acid is present in $1mole$ of acetic acid.
So the moles of acetic acid in $100g$ of acetic acid is
$= \dfrac{{100}}{{60}} = 1.67moles.$
Hence the moles of acetic acid present in $1L$ of water is $1.67moles$ and so the solution is $1.67M$ .
The normality and the molarity of acetic acid are the same because the number of equivalents changes by ionization of acetic acid is $1$. So the basicity of the acetic acid is one and hence the normality of acetic acids is equal to $1.67N$.
Hence option C is the correct answer, i.e. the normality of $10\% \left( {w/v} \right)$ of acetic acid is $1.7N$.

Note:
The normality unit is primarily used to indicate the strength of a solution. It is vastly used in acid base chemistry for recording the concentration of unknown solutions.