How many grams of oxygen is in 325.8gm of H2SO4?

Question

I got 53.14gm, but I'd like to see if I did it right. Chemistry not my strong subject.

And: How many chlorine atoms are in 254.7gm of CaCl2?
Chlorine is 35.5. How would I go about solving this problem? =/ Thank you!

Answer 1

H2SO4 has a molar mass of 2 * 1 + 16*4 + 32 * 1 = 98g/mol
There are 64g of Oxygen (4 moles * 16g) in 1 mole of H2SO4, so O2 is 64/98% of the molecule = 65.3% of the mass is Oxygen.

65.3% of 325.8 = 212.8g Oxygen.

2.) CaCl2 has a molar mass of 40 * 1 + 35.5 * 2 = 111g/mol
There are 2 moles of Cl in CaCl2, so there is 71 g Cl per 111 g CaCl2, or 63.9% Cl2.

63.9% of 254.7 = 162.9g Chlorine in CaCl2.