Question

Sulfur trioxide is made from the reaction of sulfur dioxide and oxygen. how many grams of SO3 can be made from the reaction of 1.91g SO2 with 1.29g O2?

2 SO2(g) + O2(g)---> 2SO3(g)

a) 2.39g
b) 3.20g
c) 3.23g
d) 4.77g
e) 6.46g

How would i solve this problem?? Im thinking i would use the simplest formula, but im not sure if thats right. And if so, how would i do it??

Answer 1

This is a limiting reagent problem.
1. You have the equation and it's balanced.
2a. Convert 1.91 g SO2 to moles. moles = grams/molar mass.
2b. Convert 1.92 g O2 to moles. Same procedure.

3a. Using the coefficients in the balanced equation, convert moles of SO2 (from 2a) to moles of SO3.
3b. Same process, convert moles O2 (from 2b) to moles SO3.
3c. Probably the moles from 3a and 3b will be different which means one of them is wrong. The correct number of moles, in limiting reagent problems, is ALWAYS the smaller value and the reagent producing that value is the limiting reagent.
4. Convert moles from 3c to grams. g = moles x molar mass.