AP Chemistry BOZEMAN #2 Chemical Analysis Name:
1. CH2O is the empirical formula of what molecule?
2. What is the molar mass of gold (give a unit!)?
3. Notice that even though hydrogen and oxygen are diatomics, when dividing by the
mass of each element to find moles, you only use 1 gram and 16 grams respectively. What are the three steps in finding the empirical formula when given a mass spectrum analysis?
4. SHOW WORK FOR POINTS IN THIS PROBLEM. (10 points)
Nicotine is composed of C,H, and N. A 5.250 mg sample of nicotine was combusted, producing 14.242 mg of CO2 and 4.083 mg of H2O. SIG FIGS COUNT!!!
HINT: Don't worry about the mg - make them all grams. It's all about the ratio, baby.
a) What is the mass of CO2?
b) FInd the grams of carbon in the 14.242 g of CO2 that is given:
c) Change grams of C to grams to mols of C:
d) What is the mass of H2O?
e) FInd the grams of hydrogen in the 4.083 g of H2O that is given:
f) Change grams of H to mols of H:
g) All that is left is finding the nitrogen. To do this, subtract the masses you got for the carbon (answer b) and the hydrogen (answer e) from the total number of grams in the nicotine (given in the problem). This is your grams of nitrogen.
h) Convert your grams of nitrogen to moles of nitrogen.
i) Divide by the smallest number of mols to find the mol ratio. Show your work here:
j) What is the empirical formula for nicotine?