MOLAR MASS AND FORMULA MASS
are defined as the mass of one mole of a substance
Name ______________________ Date _______ Period ______
The molar mass of one mole of an element is equal to its average atomic mass (found on the periodic
table) in grams (rather than amu’s). When determining the molar mass of the diatomic (BrINClHOF)
elements, remember to double it. The formula mass of one mole of a compound is equal to the sum of the
average atomic masses of all of the atoms in the compound in grams. When using average atomic mass
from the periodic table, the value should be rounded to two decimal places (hundredths place). The unit
is grams per mole (g/mol).
Examples: molar mass of sodium = 22.99 g/mol
molar mass of fluorine = 38.00 g/mol
formula mass of H2O = (1.01 X 2) + 16.00 = 18.02 g/mol
Name the substance and determine the molar mass or formula mass (sometimes called gram formula
mass) for the following:
Name
Molar or formula mass
1. KMnO4
_______________________
________________________
2. KCl
_______________________
________________________
3. Na2SO4
_______________________
________________________
4. Ca(NO3)2
_______________________
________________________
5. Al2(SO4)3
_______________________
________________________
6. (NH4)3PO4
_______________________
________________________
7. Mg3(PO4)2
_______________________
________________________
8. H2CO3
_______________________
________________________
9. Zn(C2H3O2)2
_______________________
________________________
10. Pb
_______________________
________________________
11. Ba(ClO3)2
_______________________
________________________
12. Fe2(SO3)3
_______________________
________________________
13. Sr
_______________________
________________________
14. Br2
_______________________
________________________
15. CuSO4●5H2O
_______________________
________________________
Honors Chemistry
Chapter 6 – Worksheet 2
Mass/Mole Conversions
Name _______________________________
Date ________
EXAMPLE: How many moles are present in 120 grams of potassium?
Formula mass = 39.10 g/mol
120 g K
1 mol K
= 3.069 mol K =
3.1 mol K
39.10 g K
1. How many moles of carbon are present in 270 grams?
2. How many moles of calcium are present in 17.5 grams?
3. What is the mass of 4.00 moles of sodium?
4. What is the mass of 3.0 x 104 moles of beryllium?
5. How many moles of neon are present in 0.00350 grams?
6. What is the mass of 0.333 moles of fluorine (think BrINClHOF)?
7. What is the mass of 2.34 moles of sodium chloride?
8. How many moles are in 5.26 grams of water?
9. How many moles are in 7.1 kg of potassium sulfide?
10. What is the mass of .56 moles of sodium acetate?
11. How many moles are in 7684 cg of calcium phosphate?
Period _____
Honors Chemistry
Chapter 6 – Worksheet 3
Mass/Particle Conversions
Name _______________________________
Date ________
Period _____
1 mole = 6.02 x 1023 particles
1 mole = formula mass in grams
EXAMPLE: How many molecules are present in 17.0 grams of carbon dioxide?
Formula mass = 12.01 + 16.00 + 16.00 = 44.01 g/mol CO2
17.0 g CO2 x 1 mol CO2
44.01 CO2
x 6.02 x 1023 molecules CO2 = 2.33 x 1023 molecules CO2
1 mol CO2
1. How many atoms are in 1 gram of silver?
2. What is the mass of 6.5 x 106 atoms of sodium?
3. What is the mass of 8.12 x 1022 molecules of water?
4. How many atoms are present in 2.7 grams of lithium?
5. How many molecules are present in 128.5 grams of CH3OH (methanol)?
6. What is the mass of one atom of boron?
Chapter 6 – Worksheet 4
Mixed Mole Practice
1. How many grams of water are present in 0.75 mol?
2. How many Cu atoms are present in 85 mol?
3. How many atoms of Cs are present in 3.45 g?
4. How many mol of NaCl are present in 150 g?
5. How many molecules of sucrose are present in 35.35 mol of sucrose?
6. How many grams of He are present in 5 x 1010 atoms of He?
7. How many atoms are present in 104 g of tungsten?
8. What is the mass in grams of 7.20 mol of antimony?
9. What is the mass in grams of 0.500 mol of C12H22O11?
10. What is the mass of 5.20 x 1010 formula units (particles) of Cu2O?
11. A sample of PbO2 has a mass of 150 g. How many moles of Pb does this sample contain?