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Problem: Calculating the molecular formula of caffeine? Caffeine, contains 49.48% Carbon, 5.15% Hydrogen, 28.87% nitrogen, 16.49% oxygen. It has a molar mass of 194.2 gmol-1.

FREE Expert Solution

We’re being asked to determine the molecular formula of a compound composed of caffeine 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 = 49.48%

H = 5.15%

N = 28.87%

O = 16.49%


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  49.48 g C, 5.15 g H, 28.87 g N, and 16.49 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

Calculating the molecular formula of caffeine? Caffeine, contains 49.48% Carbon, 5.15% Hydrogen, 28.87% nitrogen, 16.49% oxygen. It has a molar mass of 194.2 gmol-1.

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What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Molecular Formula concept. You can view video lessons to learn Molecular Formula. Or if you need more Molecular Formula practice, you can also practice Molecular Formula practice problems.

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Based on our data, we think this problem is relevant for Professor Mortazavi's class at El Paso Community College.