Question

Hydrogen reacts with oxygen to form water. If 16 g of hydrogen is mixed with 16 g of oxygen, how much water can form?

Answer 1

mass of H2 = 16 g

molar mass of H2 = 2 g/mol

moles of H2 = 16/2 = 8

mass of O2 = 16 g

molar mass of O2 = 32 g /mol

moles of O2 = 16 / 32 = 0.5

2 H2 + O2 -----------------------> 2 H2O

2           1                                    2

8           0.5                               ?

2 moles H2 --------- 1mole O2 -----------------> 2 moles of H2O

8 moles H2 --------- 0.5 moles O2 ----------------> howmany moles of H2O

here limiting reagent is O2. so the product formed based on limiting reagent . so

1mole O2 -----------------> 2 moles of H2O

0.5 moles O2 ----------------> howmany moles of H2O

moles of O2 = 0.5 x 2 = 1 mol

mole = mass / molar mass

1 = mass / 18              (H2O molar mass = 18 g /mol)

mass = 18 g

water mass produced = 18 g