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: H$_2$ - O$_2$ Fuel Cell Reaction
The balanced reaction is: \[ 2H_2 + O_2 \rightarrow 2H_2O \]Step 2: Charge Calculation
The total charge transferred is: \[ Q = It = 1 \times 595.1 \times 60 \times 60 = 2142360 { C} \]Step 3: Water Produced Calculation
The volume of water produced is: \[ \frac{36}{4 \times 96500} \times 2142360 \approx 200 { mL} \]Step 4: NaOH Molarity Calculation
The moles of NaOH are: \[ \frac{5}{40} = 0.125 { mol} \] The molarity of NaOH is: \[ \frac{0.125}{0.2} = 0.625 M \]Therefore, the correct option is (A).