#2-28: Percent Composition, Empirical Formula, and Molecular Formula:

Last updated 5 months ago
10 questions
Note from the author:
Directions:
Round all percent composition answers to one after the decimal. If you use percent composition to find empirical formula, you may want to keep a few more decimal places.
Directions:
Round all percent composition answers to one after the decimal. If you use percent composition to find empirical formula, you may want to keep a few more decimal places.
Strychnine, a rat poison, has the following chemical formula:

C21H22N2O2

1
Fill in the percent composition for each of the elements in this compound:
_______ % Carbon
_______ % Hydrogen
_______ % Nitrogen
_______ % Oxygen
You are responsible for determining an unknown over-the-counter drug substance. In the lab, you ran a test to determine that the unknown drug sample contained the following percent composition:

60.00% Carbon
4.48% Hydrogen
35.53% Oxygen
1

What is the empirical formula?

1

Identify the drug sample:

Caffeine contains the following percent composition:

49.5% Carbon
5.15% Hydrogen
28.9% Nitrogen
16.5% Oxygen
1

What is the empirical formula?

1

If the molecular mass is approximately 195.0 g/mol.

What is the molecular formula?

Aspartame, an artificial sweetener, contains the following:

4.762 moles Carbon
6.160 moles Hydrogen
0.680 moles Nitrogen
1.699 moles Oxygen
1
Fill in the percent composition for each of the elements in this compound:
_______ % Carbon
_______ % Hydrogen
_______ % Nitrogen
_______ % Oxygen
1

Determine the empirical formula:

Nitroglycerine is a compound that is used in heart medications. It can also be used in explosives!

A 40.0-gram sample of Nitroglycerine contains:
6.348 grams Carbon
0.864 grams Hydrogen
7.260 grams Nitrogen
25.364 grams Oxygen
1
Fill in the percent composition for each of the elements in this compound:

_______ % Carbon
_______ % Hydrogen
_______ % Nitrogen
_______ % Oxygen
1

Determine the empirical formula:

1

If the molecular mass is approximately 227.0 g/mol.

What is the molecular formula?