Question

In the reaction of $KMn{O}_4$ with $H_2{C}_2{O}_4$, $20$ mL of $0.2MKMn{O}_4$ is not equivalent to (in acidic medium):

• A. $120$ mL of $0.25M{H}_2{C}_2{O}_4$
• B. $100$ mL of $0.1M{H}_2{C}_2{O}_4$
• C. $500$ mL of $0.2M{H}_2{C}_2{O}_4$
• D. $10$ mL of $1M{H}_2{C}_2{O}_4$

Answer 1

Answer: (A), (C)

$120$ mL of $0.25M{H}_2{C}_2{O}_4$
$500$ mL of $0.2M{H}_2{C}_2{O}_4$

As per following reaction ionic equation:

$2Mn{O}_4^{-}+5C_2{O}_4^{2-}+16H^{+}\to 2M{n}^{2+}+10C{O}_2+8H_{2}O$. This shows for 2 mol of $MnO{4}^{2-}$ , 5 moles of $C_2{O}_4^{2-}$ are required. so, As number of moles present in 20 mL of 0.2 M $KMn{O}_4$ = 20 * 0.2/1000 = $4/1000$ moles Hence as per equation no. of moles of $H_2{C}_2{O}_4$ required = 5 * 4/1000 = 20/1000 = 1/100 moles. Now on checking for same equivalents in option A: 120 * 0.25/ 1000 = 3/100 moles , hence its not equivalent Option B: 100 * 0.1/1000 = $1/100$ moles , it is equivalent Option C : 500 * 0.2/1000 = $1/10$ , not equivalent Option D : 10 * 1/1000 =$1/100$ moles , equivalent: As asked to opt NOT EQUIVALENT so answer are Option A and C.