Molar Mass and Mole Calculation Problems

Molar Mass and Molar Mass and Mole Mole

Calculation Calculation ProblemsProblems

Molar MassMolar 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…

Give the molar masses of Give the molar masses of the following compounds: 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

• 2. potassium hydroxide KOH

• (1 x 39 grams) + (1 x 1 gram) + (1 x 16 grams) = 56 grams/mole of potassium hydroxide

• 3. copper (I) chloride CuCl

• (1 x 63.5 grams) + (1 x 35.5 grams) = 99 grams/mole of copper (I) chloride

• 4. manganese (IV) oxide MgO2

• (1 x 55 grams) + (2 x 16 grams) = 87 grams/mole of manganese (IV) oxide

• 5. calcium sulfate CaSO4

• (1 x 40 grams) + (1 x 32 grams) + (4 x 16 grams) = 136 grams/mole of calcium sulfate

• 6. magnesium phosphate Mg3(PO4)2)

• (3 x 24 grams) + (2 x 31 grams) + (8 x 16 grams) = 262 grams/mole of magnesium phosphate

How many moles of sodium How many moles of sodium are in 42 g of Na? are in 42 g of Na?

• 1.8 mol Na

How many moles of Oxygen How many moles of Oxygen are in 8.25 g of O? are in 8.25 g of O?

• 0.516 mol O

How much does 2.18 mol of How much does 2.18 mol of Cu weigh? Cu weigh?

• 139 g Cu

What is the mass of 0.28 What is the mass of 0.28 mol of iron? mol of iron?

• 16 g Fe

.    How many atoms are in .    How many atoms are in 7.2 mol of chlorine? 7.2 mol of chlorine?

• 4.3 x 1024 Cl atoms

.    How many atoms are in .    How many atoms are in 36 g of bromine? 36 g of bromine?

• 2.7 x 1023 Br atoms

How many moles are in 1.0 How many moles are in 1.0 x 10x 1099 atoms? atoms?

• 1.7 x 10-15 mol

What is the mass of 1.20 x What is the mass of 1.20 x 10102525 atoms of sulfur? atoms of sulfur?

• 639 g S

How many moles of Carbon How many moles of Carbon monoxide molecules are in 52 g of monoxide molecules are in 52 g of

CO?CO?

• 1.9 mol

.    How many moles of C.    How many moles of C22HH66 are in 124 g? are in 124 g?

• 4.12 mol

.    How many moles of CCl.    How many moles of CCl44 are there in 56 g? are there in 56 g?

• 0.36 mol

How much does 2.50 mol of How much does 2.50 mol of HH22SOSO44 weigh? weigh?

• 245 g

How much does 0.25 mol of How much does 0.25 mol of FeFe22OO33 weigh? weigh?

• 40. g

How many molecules are How many molecules are there in 52 g of CO? there in 52 g of CO?

• 1.1 x 1024 molecules