Question

what is the molar mass of h2o? 1.008 g/mol 18.015 g/mol 15.9999 g/mol 17.007 g/mol

Explanation:

Step1: Recall atomic masses

Hydrogen (H) atomic mass: $1.008\ \text{g/mol}$, Oxygen (O) atomic mass: $15.999\ \text{g/mol}$.

Step2: Calculate molar mass of $\ce{H2O}$

Molar mass = (2 × H atomic mass) + (1 × O atomic mass) = $2\times1.008 + 15.999$.
Calculate $2\times1.008 = 2.016$, then $2.016 + 15.999 = 18.015\ \text{g/mol}$.

Answer:

18.015 g/mol (corresponding to the blue option: 18.015 g/mol)