Question

1. water is 2 parts hydrogen and 1 part oxygen (h₂o). for one molecule of water, each atom has the atomic mass unit, u, shown. what percent of the mass of a water molecule is hydrogen? 16.00 u 1.01 u 1.01 u

Explanation:

Step1: Calculate mass of hydrogen in water

There are 2 hydrogen atoms, each with mass 1.01 u. So mass of hydrogen in one water molecule is $2\times1.01 = 2.02$ u.

Step2: Calculate mass of one water molecule

Mass of one water molecule is mass of hydrogen + mass of oxygen. Oxygen has mass 16.00 u. So mass of water molecule is $2.02+16.00 = 18.02$ u.

Step3: Calculate percentage of hydrogen mass

Percent of hydrogen mass = $\frac{\text{mass of hydrogen}}{\text{mass of water molecule}}\times100\%$. So it is $\frac{2.02}{18.02}\times100\%\approx 11.2\%$.

Answer:

Approximately 11.2%