Question

How many moles of KOH are required to neutralize 196 grams of sulphuric acid? (Given ${{H}_{2}}S{{O}_{4}}$ = 98 amu)?
(A) 1.1
(B) 1.5
(C) 2.0
(D) 4.0

Answer 1

Hint: We know that sulphuric acid is a strong acid and potassium hydroxide is a strong base. Addition of a base to the acid makes the acid to reach a pH value of 7. If the solution reaches pH 7, then the reaction is called a neutralization reaction.

Complete step by step solution:
- In the question, it is given that to find the number of moles of potassium hydroxide required to neutralize 196 grams of sulphuric acid.
- The molecular formula of sulphuric acid is ${{H}_{2}}S{{O}_{4}}$.
- First, we have to write a balanced equation to get the information about the reaction.
- The reaction of sulphuric acid with potassium hydroxide is as follows.
\[2KOH+{{H}_{2}}S{{O}_{4}}\to {{K}_{2}}S{{O}_{4}}+2{{H}_{2}}O\]
- In the above reaction 2 moles of potassium hydroxide reacts with one mole of sulphuric acid and forms potassium sulphate and 2 moles of water as the products.
- Given that Molecular weight of sulphuric acid is 98 amu.
\[\underset{2moles}{\mathop{2KOH}}\,+\underset{98g}{\mathop{{{H}_{2}}S{{O}_{4}}}}\,\to {{K}_{2}}S{{O}_{4}}+2{{H}_{2}}O\]
- As per the above equation 2 moles of potassium hydroxide reacts with 98 grams of sulphuric acid.
- In the question it is asked to find the number of moles of potassium hydroxide required to react with 196 grams of sulphuric acid.
- Then,
\[\begin{align}
& \text{2moles of KOH}\to \text{98 grams of sulphuric acid} \\
& \text{X moles of KOH}\to \text{196grams of sulphuric acid} \\
\end{align}\]
- We have to find X value.
- Thus,
\[\begin{align}
& \dfrac{\text{X moles}}{\text{2 moles}}\text{=}\dfrac{\text{196g}}{\text{98g}} \\
& \text{X=4 moles} \\
\end{align}\]
- Here X = number of moles of potassium hydroxide required to neutralize 196 grams of sulphuric acid.
- Therefore the number of moles of potassium hydroxide required to neutralize 196 grams of sulphuric acid is 4 moles.

So, the correct option is (D).

Note: amu means Atomic mass unit. Nothing but grams can be expressed in amu also. For 98 grams of sulphuric acid 2 moles of potassium hydroxide is sufficient to neutralize. If the amount of sulphuric acid is doubled the number of moles of potassium hydroxide required to neutralize also doubles.