Hey there!
First we need to find the molar mass of Ca(OH)₂.
Ca: 1 x 40.078
O: 2 x 16
H: 2 x 1.008
----------------------
74.094 grams
Find how many moles are in 523 grams of Ca(OH)₂.
523 ÷ 74.094 = 7.06 moles
There are 2 atoms of oxygen in each molecule of Ca(OH)₂.
7.06 x 2 = 14.12
523g of Ca(OH)₂ contains 14.12 moles of oxygen.
Hope this helps!
