Question

bonus: how many atoms of hydrogen are found in 12.6 moles of water?

Explanation:

Step1: Relate H₂O to H atoms

1 mole of $\text{H}_2\text{O}$ contains 2 moles of H atoms.
Moles of H = $12.6 \times 2 = 25.2$ moles

Step2: Use Avogadro's number

Avogadro's number: $N_A = 6.022 \times 10^{23}$ atoms/mole.
Number of H atoms = $25.2 \times 6.022 \times 10^{23}$

Answer:

$1.52 \times 10^{25}$ hydrogen atoms