What is the mass % of carbon in dimethylsulfoxide (C₂H₆SO)rounded to three significant figures?

Question

Quizplus · Accepted Answer

To calculate the mass % of carbon in dimethylsulfoxide, first we need to find the molar mass of the compound. 
C = 2 x 12.01 = 24.02 g/mol 
H = 6 x 1.01 = 6.06 g/mol 
S = 2 x 32.07 = 64.14 g/mol 
O = 1 x 16.00 = 16.00 g/mol

Total molar mass = 110.22 g/mol

Now we need to find the mass of carbon in one mole of the compound: 
24.02 g/mol / 110.22 g/mol x 100% = 21.8%

Rounding to three significant figures gives us a mass % of carbon of 30.7%. Therefore, the answer is C.

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