Question

Calculate the molarity of a solution containing 5 g of NaOH dissolved in the product of H$_2$ – O$_2$ fuel cell operated at 1 A current for 595.1 hours.(Assume F = 96500C/mol of electron and molecular weight of NaOH as 40 g/mol).

• A. 0.625 M
• B. 0.05 M
• C. 0.1 M
• D. 6.25 M

Hint:

The fuel cell produces water, which is used to prepare NaOH solution.

Answer 1

The Correct Option is A

Step 1: Understanding the H$_2$ - O$_2$ Fuel Cell
The fuel cell reaction is: \[ 2H_2 + O_2 \rightarrow 2H_2O \] Step 2: Calculating the Charge Passed
Charge passed: \[ Q = It = 1 \times 595.1 \times 60 \times 60 = 2142360 { C} \] Step 3: Finding Water Produced
Water produced: \[ \frac{36}{4 \times 96500} \times 2142360 \approx 200 { mL} \] Step 4: Calculating Molarity of NaOH
Moles of NaOH: \[ \frac{5}{40} = 0.125 { mol} \] Molarity: \[ \frac{0.125}{0.2} = 0.625 M \] Thus, the correct answer is (A).