What is the percent composition (percent by mass) of hydrogen in water? Hint:
determine the percent composition (percent by mass) first before answering question.
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%.