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