Sulfur trioxide dissolves in water, producing H2SO4. How much sulfuric acid can be produced from 13.3 mL of water (d= 1.00 g/mL) and 24.1 g of SO3?
How much of the reagent in excess is left over?

The answer is 31.5g. See solution below

SO3 + H2O => H2SO4

Theoretical moles of SO3 : H2O = 1 : 1

Moles of SO3 = mass/molar mass of SO3

= 25.7/80.064 = 0.3210 mol

Mass of H2O = volume x density

= 13.9 x 1.00 = 13.9 g

Moles of H2O = mass/molar mass of H2O

= 13.9/18.02 = 0.7714 mol

Experimentall moles of SO3 : H2O = 0.3210 : 0.7714

= 0.416 : 1 = 1 : 2.40

Since H2O is in excess, SO3 is the limiting reactant

Moles of H2SO4 = Moles of SO3 = 0.3210 mol

Mass of H2SO4 = moles x molar mass of H2SO4

= 0.3210 x 98.08

= 31.5 g

I hope this helps!