# Finding the charge passed in electrolysis of water using volume of hydrogen released [closed]

During the electrolysis of water we have gotten $$\pu{10 dm3}$$ of hydrogen. Temperature was $$\pu{0 °C}$$ and pressure was $$\pu{101325 Pa}$$.
What charge has passed trough the electrolysis article/joint?

I don't know how to find the charge while knowing pressure, temperature and volume. How do I proceed with this question?

• I have found a formula for charge that goes "Q=CxV" and I do have volume, but how do I find C (capacity), I don't remember doing that in school, but I might be mistaken. – Kat Apr 13 at 13:46

$$PV = nRT$$ and $$\ce{2H+ + 2e- -> H2}$$ are your best friends.

## Step 1: Find the number of moles of hydrogen gas released

Use the formula: $$PV = nRT$$, where $$P =$$ Pressure exerted by the gas, $$V =$$ Volume of gas, $$n =$$ number of moles of gas, $$R =$$ universal gas constant, $$T =$$ temperature of gas.

Using this formula with $$P$$ in atm and $$V$$ in liters we get:

$$n =\frac{PV}{RT} = \pu{0.0044 mol}$$

## Step 2: Find the number of farads of charge used

We know that $$\ce{2H+ + 2e- -> H2}$$

This means that for every mole of hydrogen released, $$\pu{2 moles}$$ of electrons are used. A farad is the charge on $$\pu{1 mol}$$ of electrons and so number of farads of would be two times the number of moles of electrons. So charge would be $$\pu{0.0088 F}$$.

## Step 3: One farad = 96500 coulombs

Therefore, $$\pu{0.0088 F = 850.32 C}$$ and that should be the answer.