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Question

In the reaction 2SO2(g) + O2(g) --> 2SO3(g)

 

How many g of SO3 gas at STP can be produced from 4 liters of SO2 and 3 liters of O2 all at STP?

Answer 1

For this reaction, the mole ratio of SO2 to O2 is 2 to 1.  Since there is a direct relationship between moles and liters for gases, the volume ratio is also 2 to 1.  The actual volume ratio is 4 to 3.  Therefore the oxygen is present in excess.  To calculate the mass of SO3, note that 4 L of SO2 will produce 4 L of SO3.  

g SO3 = 4 L SO3 (1 mol / 22.4 L)(80.0632 g/ mol) = 14.3 g