Answer to Question #4985 in Physical Chemistry for jermain

Question

a chemist wanted to make 100 grams of SO2. She had only 12 grams of sulfur and 4 grams of oxygen. Unfortunately, the amounts of reactants were not enough to make the desired product. How much S and O2 would she need in order to obtain the desired grams of product with no leftovers?
S + 02 = SO2 + NO LEFT OVER

Answer 1

The reaction between sulfur and oxygen looks like this:
S + O2 = SO2
As can be concluded from the reaction equation, 1 mol of sulfur reacts with 1 mol of oxygen and generates a 1 mol of SO2.
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So, if we take 12 grams of sulfur and 4 grams of oxygen, only 4 grams of sulfur will react. Thus, only 8 grams of SO2 can be obtained in such way. Other 8 g of sulfur (12 – 4 = 8) will remain in the reaction mix.
Since molecular weights of sulfur (S: 321 = 32 g/mol) and oxygen (O2: 162 = 32 g/mol) is equal, the same number of grams of S and O2 contains the same quantity of molecules. So, it’s easy to see that for synthesis of 100 grams of SO2 we should take 50 grams of sulfur and 50 grams of oxygen (1:1).

Right answer: to obtain the desired 100 grams of SO2, she should take 50 grams of sulfur and 50 grams of oxygen.