Question

8. If x grams of S are needed to obtain 0.4 grams of SO3, how many grams of SO2 can be obtained from the same amount of S?

(A) 0.32 g
(B) 0.62 g
(C) 0.40 g
(D) 0.16 g
(E) Can not be calculated from the given data.

I am not sure how to set up this problem. I calculate the molecular mass of S03 is 80.00 g, but what do I do next?

Answer 1

Compare SO3 and SO2.

the masses are in the ratio of (S+2O)/(S+3O)

multiply that by 40g

I get about 64/80 * 40

Answer 2

The chemical equation for the first reaction will be: 2S + 3O2 -> 2SO3

(.4gSO3)(1molSO3/80gSO3)=.005molSO3

Since there are 2moles of SO3 produced for every 2 moles of S, it is assumed that .005mol of S is used in the reaction to produce .4g of SO3.

To get the mass of SO2 produced using the same amount of S as of the first reaction, which is .005mol, we calculate:

(.005molS)(1molSO2/1molS)(64gSO2/1molSO2)= .32gSO2


The answer is A.