Warm up – Wed 4/17
If Jon runs 1 mile, and his
twin brother Joe runs 5280
feet, who runs farther?
Explain.
If Joe has 12 quarters, and
Jon has 3 dollar bills, who can
buy more for lunch? Explain
Dimensional Analysis
Used to convert between
units
You need to use a
conversion factor
Conversion Factor
Ratio equal to “1”
Contains the unit that you
currently have and the
unit that you want to
convert to
Examples:
12 inches = 1 foot
12 inches
1 foot
OR
1 foot
12 inches
60 seconds = 1 minute
1 minute
60 seconds OR
60 seconds
1 minute
Dimensional Analysis
Conversion
X
Unit that
you have
Unit that
you want
Unit that
you have
T-diagram
Unit that
= You want
Conversion
Factor
Single-step conversions
30 seconds = ? minutes
30 seconds 1 minute = 0.5 minute
60 seconds
Example #2
How many inches are in 3.7
feet? (12 inches = 1 ft)
3.7 ft
12 in
1 ft
= 44 in
Multi-Step Conversion
The conversion factor does NOT
contain both the unit that you have
and the unit that you want.
The unit conversion requires
multiple (more than one) steps.
Example #1
How many km are there in 34,562 cm?
Conversion factors: 100 cm = 1 m
1000 m = 1 km
34,562 cm
1m
1 km
=
100 cm 1000 m
= 0.34562 km
____km
You can do this!
How many minutes are in 2 days?
(given)
2 days
You can do this!
How many minutes are in 2 days?
(given)
2 days 24 hours 60 minutes
(given)
1 hour
1 day
= 2880
minutes
BUT… since there is only 1 digit in the given, there can
only be 1 digit in the answer so…
= 3,000 minutes
Last one!
How many seconds are in 2 decades?
Last one!
How many seconds are in 2 decades?
2 decades
10 years
365.25 days
1 decade
1 year
24 hours 60 minutes 60 seconds
1 day
1 hour
1 minute
= 631,152,000 seconds
BUT… since there is only 1 digit in the given, there can
only be 1 digit in the answer so…
= 600,000,000 seconds
Now in scientific notation…
= 6 x 108 seconds
+
MOLAR
ROAD MAP:
(draw this in
your notes)
1 mol = 22.4 l
+
Example 1
How many molecules are there in
3 moles of water?

+
Example 1
23
6.02
x
10
3.00 mole H2O
molecules H2O
1 mole H2O
Conversion Factor
= 1.81 x 1024 molecules H2O
+
Example 2

How many moles in 24.0 grams
of carbon?
+
Example 2

Conversion factor

1 mole C = 12.01 g
24.0 g C
1 mole C = 2.00 mole C
12.01 g C
Conversion Factor
+
Example 3
How
many atoms are in 3.65 g of iron?
3.65 g Fe
1 mol Fe
6.02 x 1023 atoms Fe
55.85 g Fe
1 mol Fe
= 3.93 x 10 22 atoms Fe
+
Example 4
How
many liters are in 5.5000 x 1025
molecules of hydrogen gas (at STP)?
5.5000 x 1025
molecules H2
1 mol H2
22.4 L H2
6.02 x 1023
molecules
H2
1 mol H2
= 2046.5 L H2
+
Your turn…….
#5. How many moles are
25
1.20 x 10 atoms of phosphorous?
1.20 x 1025 atoms P 1 mol P
6.02 x 1023 atoms P
= 19.9 mol P
#6. How many atoms are in
0.750 mol of Zn?
0.750 mol Zn
6.02 x 1023 atoms Zn =
1 mol Zn
4.52 x 1023 atoms Zn
Q: What did Avogadro teach his students
in math class?
A: Moletiplication
#7. How many molecules are in
0.400 mol N2O5?
0.400 mol N2O5 6.02 x 1023molecules =
1 mole N2O5
2.41 x 1023 molecules
#8. How many moles are contained
24
in 1.20 x 10 molecules CO2?
1.20 x 1024 molec CO2
= 1.99 moles CO2
1 mol CO2
6.02x 1023 molecules
#9. Find the mass in grams of
3.32 mol of K.
3.32 mol K
39.10 g K
1 mol K
2
= 1.30 x 10 g K
#10. Find the mass in grams of 15.0
mol of sulfuric acid.
H2SO4
H 2 x 1.01 = 2.02
S 1 x 32.1 = 32.07
O 4 x 16.0 = 64.00
98.09 g
15.0 mol H2SO4 98.09 g H2SO4
1 mol H2SO4
= 1470 g H2SO4
#11. Find the number of moles in
187 g of aluminum.
187g Al
1 mol Al
27.0 g Al
= 6.93 mol Al
#12. Find the number of moles in
11.0 g of methane (CH4).
CH4 = (12.0 + 4.0 = 16.0 g)
11.0 g CH4 1 mol CH4
16.0 g CH4
= 0.688 mol CH4
#13. Calculate the number of molecules
present in 4.29 g of nitrogen dioxide.
4.29g NO2 1 mol NO2 6.02 x 1023 NO2 molec
46.0g NO2 1 mol NO2
= 5.61
x 1022 molecules NO2
#14. Calculate the mass in grams of
2.49 x 1020 carbon dioxide molecules.
2.49 x 1020 CO2 molec 1 mol CO2
44.0 g CO2
6.02 x 1023 CO2 molec 1mol CO2
= 0.0182 g CO2
#15. What is the volume (liters)
at STP of 0.960 mol of methane,
CH4?
0.960 mol CH4
= 21.5 L CH4
22.4 L CH4
1 mol CH4
Thursday 4/18 Warm-up
At STP, how many moles are in
0.542 mL of neon gas?
(hint: 1L = 1000mL)
0.542 mL Ne 1 L Ne
1 mol Ne
1000 mL Ne 22.4 L Ne
= 2.42 x 10-5 mol Ne