Question

10 grams of hydrogen is burnt in the presence of excess oxygen the mass of water found is

Answer 1

Equation : H₂ + O₂ => H₂O

Balanced Equation = 2 H₂ + O₂ => 2 H₂O

So 2 moles of H₂ reacts with one mole of oxygen to produce 2 moles of water.

2 moles of H₂ = 2 * Molar Mass = 2 * 1 = 4 g

1 mole of O₂ = 1 * Molar mass = 1 * 16 = 16 g

1 mole of H₂O = 36 g

So 2 g reacts with 16 g of oxygen to produce 36 g

But in the question it is given excess oxygen. Hence mass of oxygen will increase to twice it's previous amount as formula changes to 2 O₂.

So equation = 2 H₂ + 2 O₂ => 2 H₂0

So 4 g => 36 g

then, 10 g => ?

Cross multiplying we get,

4 g * x = 10 g * 36 g

x = 36 g * 10 g / 4 g

x = 360 g / 4 g

x = 90 g of water

Hence 90 g of water will be formed.

x = 45