1. Molar Mass and Mole Calculation Problems

2. Molar Mass
You need to calculate molar mass if you have more than one atom in a problem.
It’s easy… just add the masses together and multiply time the number of atoms in the molecule (subscript)
For example: H2O Hydrogen =1 Oxygen =16; There are 2 hydrogens and 1 oxygen so the total is 18g for molar mass…

3. Give the molar masses of the following compounds:
1. sodium fluoride NaF
(1 atom x 23 grams/mole of sodium) + (1 atom x 19 grams/mole of fluorine) = 42 grams/mole of sodium fluoride

4. 2. potassium hydroxide KOH
(1 x 39 grams) + (1 x 1 gram) + (1 x 16 grams) = 56 grams/mole of potassium hydroxide

5. 3. copper (I) chloride CuCl
(1 x 63.5 grams) + (1 x 35.5 grams) = 99 grams/mole of copper (I) chloride

6. 4. manganese (IV) oxide MgO2
(1 x 55 grams) + (2 x 16 grams) = 87 grams/mole of manganese (IV) oxide

7. 5. calcium sulfate CaSO4
(1 x 40 grams) + (1 x 32 grams) + (4 x 16 grams) = 136 grams/mole of calcium sulfate

8. 6. magnesium phosphate Mg3(PO4)2)
(3 x 24 grams) + (2 x 31 grams) + (8 x 16 grams) = 262 grams/mole of magnesium phosphate

9. How many moles of sodium are in 42 g of Na?
1.8 mol Na

10. How many moles of Oxygen are in 8.25 g of O?
0.516 mol O

11. How much does 2.18 mol of Cu weigh?
139 g Cu

12. What is the mass of 0.28 mol of iron?
16 g Fe

13. . How many atoms are in 7.2 mol of chlorine?
4.3 x 1024 Cl atoms

14. . How many atoms are in 36 g of bromine?
2.7 x 1023 Br atoms

15. How many moles are in 1.0 x 109 atoms?
1.7 x mol

16. What is the mass of 1.20 x 1025 atoms of sulfur?
639 g S

17. How many moles of Carbon monoxide molecules are in 52 g of CO?

18. . How many moles of C2H6 are in 124 g?

19. . How many moles of CCl4 are there in 56 g?

20. How much does 2.50 mol of H2SO4 weigh?

21. How much does 0.25 mol of Fe2O3 weigh?

22. How many molecules are there in 52 g of CO?
1.1 x 1024 molecules