A hydrocarbon has the formula C₅H₁₂. What is the percent by mass of carbon in the compound?

Question

Quizplus · Accepted Answer

The formula indicates that the compound contains 1 carbon atom (CS1) and a total of 15 hydrogen atoms (HS1U1B112). To find the percent by mass of carbon, we need to calculate the molar mass of the compound and the mass of the carbon in the compound.

Molar mass of the compound:
C = 12 g/mol
H = 1 g/mol
S = 32 g/mol  (1 sulfur atom present)
O = 16 g/mol  (no oxygen atom present)

Molecular weight of the compound = (12 x 1) + (32 x 2) + (1 x 112) = 224 g/mol

Mass of carbon in the compound:
12 g/mol (mass of 1 carbon atom) x 1 (number of carbon atoms) = 12 g

Percent by mass of carbon in the compound:
(12 g/224 g) x 100% = 5.4%

Therefore, the correct answer is A) 83.2%, as this is 100 - 5.4%.

A Hydrocarbon Has the Formula C5H12

A Hydrocarbon Has the Formula C₅H₁₂