SCH 3U
Name__________________________
Calculations with The Mole
Calculations with the mole involve using mass, number of entities, and mole ratios. But how big is a mole really? The
following activities will help to give you an understanding of how big a mole truly is.
Use proper problem solving format for the following stations:
Station #1 – How many water molecules will fit in your mouth?
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Fill a small glass with water and record its mass. _______________________g
Fill your mouth with as much water as possible from the glass.
Record the new mass of water and glass. _____________________________g
Determine the mass of water that will fit in your mouth. _________________g
Determine the number of water molecules that will fit in your mouth.
Station #2 – How many molecules of chalk does it take to write your name?
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Record the mass of a piece of chalk. _________________________________g
Write your name on the board and re-weigh the chalk. __________________g
Determine the mass of chalk used to write your name ___________________g
Chalk is made of calcium carbonate. Determine the molar mass of chalk. _________________g/mol
Determine the number of chalk molecules that it takes to write your name.
Station #3 – How many moles of copper are in a single penny?
1. Use the balance to determine mass of 3 pennies. Record the average mass. __________________g
2. Using this mass, calculate the number of moles in your average penny assuming the entire penny is copper.
Station #4 – How many molecules of sugar are in one tablespoon of sugar?
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Determine the mass of a weight boat (white plastic dish). ________________g
Scoop 1 tablespoon of sugar into the dish and record the total mass ________g
Calculate the mass a one tablespoon of sugar. __________________________g
If the formula for sugar is c12H22O11, determine how many sugar molecules are in one tablespoon.
Questions:
1. Why does one mole of sugar have a greater mass than one mole of water?
2. Old pennies (1960 and earlier) are made entirely of copper. Newer pennies are made of zinc and coated with a
thin layer of copper. Why do you think this happened?
3. If the average mass of a piece of chalk is 5.250g, how many times would you be able to write your name?
SCH 3U
Mole Practice Problems
1) How many moles are in the following:
a. 1.29 x 1024 hydrogen
b. 7.36 x 1024 oxygen atoms
c. 3.28 x 1023 Na atoms
d. 24.0 g of carbon
e. 0.0050 g of Neon
f. 59.3 g of Sn
2) How many atoms are present in the following?
a. Hydrogen atoms in 3.14 mol of H2O
b. Nitrogen atoms in 2.79 mol of NH3
c. Oxygen atoms in 4.90 mol in Al2O3
3) How many atoms are in a 3.56 g sample of Cu?
4) How many grams of CaCO3 are present in a sample if there are 4.52 x 1024 molecules in that sample?
5) How many atoms of chlorine would be found in 4.20g of magnesium chloride?
Answers
1. a) 2.14 mol
b) 12.2 mol
2. a) 3.78 x 1024 atoms
3. 3.37 x 1022 Cu atoms
4. 751 g CaCO3
5. 5.31 x 1022
c) 0.545 mol
d) 2.00 mol
b) 1.68 x 1024 atoms
e) 2.5 x 10-5 mol
c) 8.85 x 1024 atoms
f) 0.500 mol