What is the percent composition (percent by mass) of hydrogen in water? Hint:

Question

determine the percent composition (percent by mass) first before answering question.

Answer 1

To determine the percent composition of hydrogen in water, we need to know the molecular formula for water, which is H2O.

The molecular weight of H2O is:

2(1.008 g/mol) + 1(15.999 g/mol) = 18.015 g/mol

The mass of hydrogen in H2O is:

2(1.008 g/mol) = 2.016 g/mol

To find the percent composition of hydrogen in water, we divide the mass of hydrogen by the total molecular weight of H2O:

(2.016 g/mol / 18.015 g/mol) x 100% = 11.19%

Therefore, the percent composition of hydrogen in water is approximately 11.19%.