What is the mass of oxygen in 250 g of sulfuric acid, H2SO4?
Do you multiply 4 x 16 to get 64 and then divide 250g by 64 to get 3.9g or is my answer wrong plz help! Thanks.
3 Answers

the molecular mass of H2SO4 is 2 + 32 + 4×16 = 98
so the mass % of O = 64/98 = 65.3%
so the mass of O = 250g x 65.3% = 163g

No because if you do that to the other elements it doesnt add upto 250g.
Find the RMM of H2SO4 then divide the actual mass by the RMM.
So yu get bout 2.5 moles of H2SO4 then times 64 by 2.5 and you have your answer i think.

1) Find the molecular weight of sulfuric acid. Take the molecular weights of the individual atoms and add them up.
H = 1.008 (x2) S = 32.065 O = 16 (x4)
(2×1.008) + (1×32.065) + (16×4) = ~ 98.081 g/mole
This means that there are 98.081 grams in every mole of sulfuric acid
2) Find the number of moles in 250 g of sulfuric acid.
250 g x (1mole/250g) = 2.5489 moles of sulfuric acid
3) Determine the number of moles of oxygen in 2.5489 moles of sulfuric acid. This can be determined by finding the ratio of oxygen to sulfuric acid. For every 1 mole of sulfuric acid, there are 4 moles of oxygen. Thus:
2.5489 moles sulfuric acid x (4 moles oxygen / 1 mole sulfuric acid) = 10.19565 moles of oxygen
4) Determine the mass of oxygen in 10.19565 moles of oxygen.
Molecular Weight of Oxygen = ~16 g/mole
10.19565 moles x (16 g / 1 mole) = 163.13 grams
Answer = 163.13 grams of oxygen in 250 grams of sulfuric acid