Name _____________________________________
Formula Test Multiple Choice
1. What does the formula for a compound tell you?
A) the number of atoms
B) the types of atoms
C) the number and types of atoms D) none of the above.
2. The mass of a compound is made of:
A) the mass of only one element
B) the mass of water
3. Percent composition tells you:
A) the percent of the atoms present for each element
C) the percent of the molecules present
C) larger masses D) smaller masses
B) the percent of the molecule
D) the percent of only one of the elements present
4. When you are done finding the percent composition, the total percent should equal:
A) 10%
B) 100% C) 50%
D) 75%
5. A formula that gives the simplest whole number ratio of the atoms of the elements is:
A) a molecular formula
B) a structural formula
C) an empirical formula D) none of the above
6.
An empirical formula tells you:
A) how many of each type of atom you have in an element
B) The ratio of atoms
C) The number of atoms
D) The type of atoms
7. If you are given the percent compositions and asked to find the empirical formula, what do you assume?
A) 10 g of sample
B) 50 g of sample
C) 75 g of sample
D) 100 g of sample
8.
True or False: The molecular formula is never the same as the empirical formula.
9. The molecular formula is:
A) not related to the empirical formula
B) a whole number multiple of the empirical formula
C) always smaller than the empirical formula
D) always equal to the empirical formula
10. Which of the following do you need to know in order to find the molecular formula?
A) molecular mass of the formula
B) empirical formula
C) percent composition
11. What is the efm?
A) empirical/molecular formula
B) empirical formula mass C) ending mass formula
Short Answer
1.
Explain how the empirical and molecular formulas are related.
2.
Describe how you calculate a percent. An example is fine.
Percent composition
Find the percent composition of each element in H2SO4.
D) both A and B
Name _____________________________________
Empirical Formulas
Determine the empirical formula of a compound containing 75 g of carbon and 25 g of hydrogen.
Find the empirical formula of a compound made of 13% Mg and 87% Br.
Molecular Formulas
The empirical formula of a compound is CH2. Its molecular mass is 70 g/mol, what is its molecular formula?