Question

When 5.00 g of sulfur are combined with 5.00 g of oxygen, 10.00 g of sulfur dioxide (SO2) are formed. What mass of oxygen would be required to convert 3.00 g of sulfur into sulfur trioxide (SO3)?

Answer 1

molar mass of S = 32 g/mol
number of mole of S = (given mass)/(molar mass)
= 3.00/32
= 0.094 mole
reaction taking place is
2S + 3O2 -- > 2SO3
according to reaction
2 mole of S required 3 mole of O2
1 mole of S required 3/2 mole of O2
0.094 mole of S required (3/2*0.094) mole of O2
so, number of mole of O2 required = (3/2*0.094)
= 0.14 mole

molar mass of O2 = 32 g/mol
mass of O2 required = (number of mole of O2)*(molar mass of O2)
= 0.14*32
= 4.5 g

Answer : 4.5 g