Question

When a 19.34 gram piece of lithium is placed in a sample of water, how many grams of hydrogen gas are?

Answer 1

The reaction given by

• Li+H_2O—»Li(OH)_2+H_2

Moles of Li

• 19.34/6.99
• 2.8mol

1 mol Lithium produces 1 mol H_2

2.8mol produces

• 2.8mol H_2

i.e 2.8(2)=5.6g hydrogen