Question

Concentrated aqueous sulfuric acid is 98% ${{H}_{2}}S{{O}_{4}}$ by mass and has a density of 1.80$gm{{L}^{-1}}$. Volume of acid required to make one litre of 0.1M ${{H}_{2}}S{{O}_{4}}$ is:
A. 5.55 mL
B. 11.10 mL
C. 16.65 mL
D. 22.20 mL

Answer 1

Hint: Calculate the volume of acid required by taking into account the data provided and use formula for normality to calculate the volume.

Complete step by step answer:
METHOD 1 –
We can directly use the data given in the question in the following way by relating normality and volume.
\text{Normality = }\dfrac{\text{weight }\\!\\!%\\!\\!\text{ x density x 10}}{\text{equivalent weight}}=\dfrac{\text{9}\text{.8 x 1}\text{.8 x 10}}{\text{49}}\text{ = 36N}
Since, ${{\text{N}}_{\text{1}}}{{\text{V}}_{\text{1}}}\text{=}{{\text{N}}_{\text{2}}}{{\text{V}}_{\text{2}}}$
$\Rightarrow \text{ 36 x }{{\text{V}}_{\text{1}}}\text{= 0}\text{.2 x 1000}$
Therefore, ${{\text{V}}_{\text{1}}}\text{ = }\dfrac{\text{0}\text{.2 x 1000}}{\text{36}}\text{ = 5}\text{.55 mL}$

METHOD 2 –
According to the question, we have been given concentrated aqueous sulfuric acid which is 98% ${{H}_{2}}S{{O}_{4}}$ by mass, which means –
$\text{98 }\\!\\!$
We’ve also been given density of concentrated aqueous sulfuric acid; therefore, we can find volume of 100g solution by –
$\text{Volume of 100g solution = }\dfrac{\text{mass}}{\text{density}}\text{=}\dfrac{\text{100}}{\text{1}\text{.8}}\text{=55}\text{.55mL}$

& \text{For 0}\text{.1 M, we need 9}\text{.8g }{{\text{H}}_{\text{2}}}\text{S}{{\text{O}}_{\text{4}}} \\\ & \therefore \text{ 55}\text{.55 mL acid = 98g} \\\ & \text{5}\text{.55 mL acid =9}\text{.8 g = 0}\text{.1 Molar acid} \\\ \end{aligned}$$ Therefore, the answer is – option (a) Note: Keep the following points in mind about Normality – Symbol: N Definition: “It is defined as the gram equivalent weight per litre of solution”. Formula: $$\text{Normality = }\dfrac{\text{mass of solute (g)}}{\text{equivalent mass x volume of solution (L)}}$$ Unit: gram equivalent/ L