An unknown acid has a molar mass of 60.06 g/mol.Given the following percent composition,what is the molecular formula?
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Question

An unknown acid has a molar mass of 60.06 g/mol.Given the following percent composition,what is the molecular formula? 
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Quizplus · Accepted Answer

To find the molecular formula, we need to first determine the empirical formula using the percent composition. Converting each percent to grams, we have:

C: 37.62 g
H: 5.93 g
S: 31.53 g
O: 24.92 g

Next, we need to determine the ratios of the elements in the empirical formula. We can do this by dividing each gram amount by its molar mass and then dividing each of those values by the smallest value. This gives us:

C: 3
H: 14
S: 3
O: 3

So, the empirical formula is C3H14S3O3.

To determine the molecular formula, we need to find the factor by which the empirical formula must be multiplied to give the molar mass of 60.06 g/mol. We can do this by finding the molar mass of the empirical formula, which is:

(3 x 12.01 g/mol) + (14 x 1.01 g/mol) + (3 x 32.07 g/mol) + (3 x 16.00 g/mol) = 180.44 g/mol

Dividing the molar mass of the unknown acid by the molar mass of the empirical formula gives us:

60.06 g/mol ÷ 180.44 g/mol = 0.3327

Rounding this to the nearest whole number (which gives us a factor of 1), we can say that the molecular formula is the same as the empirical formula, which is C3H14S3O3.

Option C is the only one that contains all the elements in the empirical formula and in the correct ratios.

An Unknown Acid Has a Molar Mass of 60