Determine the mass of hydrogen required to obtain 1.8 times 10 to the 24 power of water molecules?

1.Let’s find the amount of water substance.

N = n NA, where NA is Avogadro’s number equal to 6 × 10 ^ 23.

n = N: NA.

n = 1.8 × 10 ^ 24: 6 × 10 ^ 23 = 0.3 × 10 = 3 mol.

Let’s compose the reaction equation.
2H2 + O2 = 2H2O.

According to the reaction equation, 2 mol of water accounts for 2 mol of hydrogen.

The substances are in quantitative ratios of 1: 1.

The amount of water and hydrogen will be the same.

Let’s find the mass of water.

m = n × M.

M (H2O) = 18 g / mol.

m = 3 mol × 18 g / mol = 54 g.

Answer: 54 g.