Question

The atomic mass of hydrogen is 1.01. What is the mass of hydrogen in one mole of aluminum hydroxide (Al(OH)3)?

Answer 1

The answer is 3.03 g

Ar(H) = 1.01 g/mol
Since there are three atoms in Al(OH)3, the total atomic mass of hydrogen in Al(OH)3 is:
3 * Ar(H) = 3 * 1.01 g/mol = 3.03 g/mol

The mass (m) is atomic mass (Ar) divided by the number of moles n):
m = Ar/n
Ar = 3.03 g/mol
n = 1 mol
m =  3.03 g/mol / 1 mol = 3.03 g