Question

How many grams of $NaOH$ will be required to neutralize 12.2 g benzoic acid?
(a) 12.2 g
(b) 16g
(c) 40g
(d) 4g

Answer 1

Hint: First find out the molecular mass of the $NaOH$ and benzoic acid and from it first find how much $NaOH$ is required to neutralize the 1g of the benzoic acid and then , use can easily find the $NaOH$ used to neutralize the 12.2 g of benzoic acid.

Complete step by step solution:
$NaOH$ is a strong base and has a pH of more than 7 and has a strong tendency to neutralize the other acids and such reactions are called the neutralization reactions.
Considering the given numerical;
In this, we have to find out the grams of $NaOH$ required to neutralize the 12.2 g of benzoic acid.
So, as we know that, molecular mass of $NaOH$\[=23+16+1\text{ =}40\text{ }g\]
Similarly, molecular mass of the benzoic acid i.e.
$\begin{align}
& {{C}_{5}}{{H}_{5}}COOH=12\times 5+5\times 1+12+16+16+1 \\
& \text{ = 60+5+12+33} \\
& \text{ = 110 }g \\
\end{align}$
Then ,if
110g of the benzoic acid is neutralized by the =40 g of the $NaOH$
Similarly,
1g of the benzoic acid will be neutralized by the =$\dfrac {40}{110}$ g of the $NaOH$
Now then,
12.2g of the benzoic acid will be neutralized by the =$\dfrac{40}{110}\times 12.2$ g of the $NaOH$
=\[\dfrac{488}{110}\] g of the $NaOH$
=4 g of the $NaOH$
So, thus in order to neutralize the 12.2 g of the benzoic acid, we need to take 4 g of the $NaOH$.

Hence, the option (d) is correct.

Note: $NaOH$ is strong base and it turns red litmus blue indicating that it is basic in nature and is used in the manufacture of many detergents and soaps etc. and it is very soluble in water than in the non-polar solvent like the alcohol etc.