Question

Electrolysis of water occurs according to the following equation...

2H20 ->2H2+O2

If electrolysis is performed with 100% efficiency on 100 grams of water. How many grams of hydrogen gas will be produced?

a. 11 grams
b. 50 grams
c. 4 grams
d. 100 grams

Answer 1

11.1g

Step-by-step explanation:

Given parameters:

Mass of water = 100g

Unknown:

Mass of hydrogen gas = ?

Solution:

We need to write the balanced reaction equation first and solve from the known to the unknown;

2H₂O → 2H₂ + O₂

Now, find the number of moles of the given specie;

Number of moles of H₂O =
`(mass)/(molar mass)`

Molar mass of H₂O = 2(1) + 16 = 18g/mol

Number of moles =
`(100)/(18)` = 5.56mol

2 mole of water produced 2 mole of hydrogen gas;

5.56 mole of water will produce 5.56 mole of hydrogen gas

Mass of hydrogen gas = number of moles x molar mass

molar mass = 2(1) = 2g/mol

Mass of hydrogen gas = 2(5.56) = 11.1g