UNIT CONVERSION FACTORS
INITIAL
AMOUNT (units)
X
CONVERSION
FRACTION
=
UNKNOWN
AMOUNT (units)
Example: Find how many litres are in 35 mL.
35 mL
initial amount
(2 sd’s)
x
1L
1000mL
=
conversion
fraction
0.035 L
NOTE: answer must have the correct # of
significant digits (SD’s don’t apply to conversion
factors)
unknown
amount (2 sd’s)
1. How many Kg are in 950 grams?
2. How many seconds are in 3.6 hours?
3. How many dozen eggs are there if you have 62 eggs?
4. How many tires do 20 cars have?
5. How many milliliters are in 1.7 Litres?
6. If the rate of a reaction is 360g/s, find out how much reacts in Kg/min.
7. How many litres in 1,785 mL?
8. If oranges are $2.88/dozen, how much would 4.5 dozen oranges cost?
9. How many atoms are found in 34 molecules of AlCl3?
10. How many mg are in 15 grams of calcium?
UNIT CONVERSION FACTORS
THE MOLE CONCEPT:
“12 is Not Enough”
1 dozen = 12 objects
1 pair = 2 objects
1 mole = 6.02 x 1023 objects*
CONVERSION
FACTOR:
* objects may represent # of atoms, molecules, eggs,
etc. so that 1 mol of eggs = 6.02 x 1023 eggs
6.02 x 1023 objects
1 mol
HOW BIG IS THE MOLE?
•
6.02 x 1023 marshmallows would cover Australia to a depth of 105,000 km
•
One mole of mice (17 cm long) placed head-to-toe would stretch 11 million
light years and weigh as much as the moon.
•
One mole of marbles would form a mountain 116 times higher than Mt.
Everest with a base the size of Australia
AVOGADRO’S HYPOTHESIS
Where did the mole come from? Avogadro experimentally determined that
22.4 L of any gas (eg. H2, CO2, etc.) will always contain 6.02 x 1023 particles
EXAMPLE:
How many moles of eggs are there if you have 3.01 x 1023 eggs?
3.01 x 1023 eggs x
1 mol
=
23
6.02 x 10 eggs
0.500 mol
1. How many books are in 0.75 mol of books?
2. How many molecules of H2O are in 1.62 mol?
3. How many oxygen atoms in 0.870 mol of CO2?
22.4 L
UNIT CONVERSION FACTORS
4. How many atoms are there in 43 molecules of NaCl?
5. How many moles in 4.2 x 1023 atoms of gold?
6. How many moles of AlCl3 are there in 1.81 x 1014 molecules of AlCl3?
7. How many cars are there in 2.5 mol of cars?
8. How many moles are there in 143 bananas?
9. How many MgSO4 molecules in 1.43 mol of MgSO4?
10. How many moles of molecules are there in 65 molecules of Calcium chloride?
11. How many atoms are there in 3.2 x 10-5 moles of Iron (III) bromide?
12. How many wheels are there in 2.6 moles of bicycles?
13. How many oxygen atoms are in 3.8 moles of water molecules?
14. How many atoms are in 3 molecules of Barium chloride?
ANSWERS:
1. 4.5 x 1023
2. 9.75 x 1023
3. 1.05 x 1024
4. 86
5. 0.71
6. 3.01 x 10-10
7. 1.5 x 1024
8. 2.37 x 10-22
9. 8.61 x 1023
10. 1.1 x 10-22
11. 7.7 x 1019
12. 3.1 x 1024
13. 2.3 x 1024
14. 9