Problem : If the percent yield of the following equation is 55%, how many moles of H2SO4 are produced when 44.8 L of SO3 are combined with excess water?

SO3(g) + H2O(l)→H2SO4(aq)    

The equation is balanced, so convert to moles.

= 2 moles SO3(g)    

Now calculate the theoretical yield. How many moles of H2SO4(aq) should we get?

= 2 moles H2SO4(aq)    

Now solve algebraically for the actual yield.

55% = 0.55 = Actual Yield/(2 moles H2SO4(aq))    
2 moles H2SO4(aq)×0.55 = 1.1 moles H2SO4(aq)