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M19 - Combustion Analysis

Posted: Mon Apr 09, 2018 3:14 pm
by AnnaYan_1l
The question asks, "A stimulant in coffee and tea is caffeine, a substance of molar mass 194 g mol 1. When 0.376 g of caffeine was burned, 0.682 g of carbon dioxide, 0.174 g of water, and 0.110 g of nitrogen were formed. Determine the empirical and molecular formulas of caffeine, and write the equation for its combustion."

How would I go about solving this problem? Thank you!

Re: M19 - Combustion Analysis

Posted: Mon Apr 09, 2018 4:06 pm
by ErinKim1I
Find the moles of C, H, N, and O as these are the elements in caffeine.
Then, divide by the smallest coefficient to get the EF.
Divide the given molar mass of caffeine by the molar mass of the EF to get the ratio.
multiply the resulting number by the EF to get the MF.
To write the equation: MF of caffeine + O2 --> CO2 + H2O+ N2
balance this skeletal equation.

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Re: M19 - Combustion Analysis

Posted: Mon Apr 09, 2018 8:58 pm
by AnnaYan_1l
Thank you!!! That makes so much sense now.