Name _______________________________ Date______________ Period
Molecular Weight, Formula Weight and Mole Calculations
Practice Problems Worksheet #2
There are different ways of describing the size of a sample of a substance. We can describe its amount in terms of:
- the mass of the sample
- the number of particles (atoms or molecules) in the sample
Mass
Mole
# Particles
- the number of the moles of particles in the sample
The three quantities are all related to one another through the mole. If we know the size of a sample in terms of any one of
the three quantities, we can calculate the amounts of the other two. For example, from a given mass we can calculate the
number of the moles, and from the number of moles we can calculate the number of particles.
Remember:
- One mole of particles (atoms or molecules) has a mass in grams equal to the atomic or molecular mass in amu’s.
- One mole of particles equals 6.02 x 1023 particles.
Molecular Weight and Formula Weight
DIRECTIONS: Find the molecular weight or the formula weight for each of the following compounds.
1. CO
11. KBr
2. NaCl
12. water
3. SO2
13. CuSO4
4. K2S
14. MgF2
5. HNO3
15. Na2SO3
6. Cs2SO4
16. Cu(NO3)2
7. Nd2O3
17. NH4Br
8. Al(OH)3
18. Fe3(PO4)2
9. Fe(C2H3O2)2
19. Mg3N2
10.Sb(NO3)3
20. KAl(SO4)2*12H2O
Mole Calculations
DIRECTIONS: Find the number of moles represented by each of the following masses.
1) 17.0 g of NH3
ANSWER:
2) 98.1 g of H2SO4
ANSWER:_
3) 58.5 g of NaCl
ANSWER:
4) 88.0 g of CO2
ANSWER:
5) 0.50 g of hydrogen gas (H2)
ANSWER:
6) 1.582 g of potassium nitrate (KNO3)
ANSWER:
7) 20.0 g of HClO4
ANSWER:
8) 1000. g of aluminum iodide (AlI3)
ANSWER:
9) 0.100 g of copper (II) sulfate (CuSO4)
ANSWER:
10) 50.0 g of phosphoric acid (H3PO4)
ANSWER:
11) 0.2835 g of aluminum sulfite Al2(SO3)3
ANSWER:
12) 30.5 g of Li3PO4
ANSWER:
13) 6.58 g of TmF3
ANSWER:
14) 0.00500 g of gold (III) chloride (AuCl3)
ANSWER: