Question

4 grams of hydrogen reacts with some oxygen to make 36 grams of water. Figure out how much oxygen must have been used by applying the law of conservation of mass?​

Answer 1

The amount of oxygen used to produce 36 g of water is 32 g.

Explanation:

The chemical reaction for the formation of water is:

2H₂ + O₂ → 2H₂O

Now,

36 × 1/18 = 2 moles of water

4 g of H₂ × 1/2 = 2 moles of hydrogen

On applying the law of conservation of mass, two moles of hydrogen and 1 mole of oxygen reacts to produce 2 moles of water.

Thus, one mole of oxygen is required to produce 2 moles of water.

1 mole of oxygen × 32 g/mole of water = 32 g of oxygen

Answer 2

Answer:The mass of oxygen will be 32g

Explanation:    according to law of conservation

the mass of reactants =  the mass of product

hydrogen+ oxygen =water

4g + xg = 36g

xg= 36g - 4g

xg= 32g (hence proved)