Problem: A compound has 67.3% C,4.62% N,6.93% H and O. Determine the molecular formula of the compound knowing its molar mass is 283 g/mol.

FREE Expert Solution

We’re being asked to determine the molecular formula of a compound given the mass percent of C, H, N, and O. This means we need to do the following steps:


Step 1: Calculate the mass and moles of C, H, N and O in the compound.

Step 2: Determine the lowest whole number ratio of C, H, N and O to get the empirical formula.

Step 3: Get the ratio of the molar mass and empirical mass to determine the molecular formula.


Step 1: The compound is composed of C, H, N, O

C = 67.3%

H =6.93%

N = 4.62%

O = 100% -[ 67.3% + 6.93% + 4.62%] = 21.15 %

Recall that mass percent is given by:


%Mass = mass of Xtotal mass×100


Assuming we have 100 g of the compound, this means we have  67.3 g C, 6.93 g H, 4.62 g N, and 21.15 g O. Now, we need to get the moles of each element in the compound. The atomic masses are 12 g/mol C, 1 g/mol H, 14g/mol N, and 16 g/mol O.


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Problem Details

A compound has 67.3% C,4.62% N,6.93% H and O. Determine the molecular formula of the compound knowing its molar mass is 283 g/mol.

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