1. Mass vs. Weight
Mass depends on the amount of ___________ in the object.
Weight depends on the force of ____________ acting on the object.
______________ may change as you move from one location to another; ____________ will not.
You have the same ____________ on the moon as on the earth, but you ___________ less since there is less _________ on the moon.
matter
gravity
Weight
mass
Mass = 80 kg
Weight = 176 lbs.
mass
weigh
gravity
Mass = 80 kg
Weight = 29 lbs.

2. The SI System (The Metric System)‏
Here is a list of common units of measure used in science:
Standard Metric Unit Quantity Measured
kilogram, (gram) ______________
meter ______________
cubic meter, (liter) ______________
seconds ______________
Kelvin, (˚Celsius) _____________
The following are common approximations used to convert from our English system of units to the metric system:
1 m ≈ _________ kg ≈ _______ L ≈ 1.06 quarts
1.609 km ≈ 1 mile gram ≈ ______________________
1mL ≈ _____________ volume 1mm ≈ thickness of a _______
mass
length
volume
time
temperature
1 yard
2.2 lbs.
mass of a small paper clip
sugar cube’s
dime

4. kilo- hecto- deka- deci- centi- milli-
Metric Conversions
The metric system prefixes are based on factors of _______. Here is a list of the common prefixes used in chemistry:
kilo- hecto- deka deci- centi- milli-
The box in the middle represents the standard unit of measure such as grams, liters, or meters.
Moving from one prefix to another involves a factor of 10.
*Example: 1000 millimeters = 100 ____ = 10 _____ = 1 _____
The prefixes are abbreviated as follows:
k h da g, L, m d c m
*Examples of measurements: 5 km 2 dL 27 dag 3 m 45 mm
ten cm dm m
grams Liters meters

5. 380 km = ______________m 1.45 mm = _________m
Metric Conversions
To convert from one prefix to another, simply count how many places you move on the scale above, and that is the same # of places the decimal point will move in the same direction.
Practice Problems:
380 km = ______________m mm = _________m
461 mL = ____________dL cg = ____________ dag
0.26 g =_____________ mg ,000 m = _______km
Other Metric Equivalents
1 mL = 1 cm L = 1 dm3
For water only:
1 L = 1 dm3 = 1 kg of water or mL = 1 cm3 = 1 g of water
(1) How many liters of water are there in 300 cm3 ? ___________
(2) How many kg of water are there in 500 dL? _____________
kilo- hecto- deka deci- centi- milli-
380,000
4.61
0.0004
260
230
0.3 L
50 kg

6. Metric Volume: Cubic Meter (m3)
10 cm x 10 cm x 10 cm = Liter

7. Problem Solving in Chemistry
Dimensional Analysis
Used in _______________ problems.
*Example: How many seconds are there in 3 weeks?
A method of keeping track of the_____________.
Conversion Factor
A ________ of units that are _________________ to one another.
*Examples: 1 min/ ___ sec (or ___ sec/ 1 min)
___ days/ 1 week (or 1 week/ ___ days)
1000 m/ ___ km (or ___ km/ 1000 m)
Conversion factors need to be set up so that when multiplied, the unit of the “Given” cancel out and you are left with the “Unknown” unit.
In other words, the “Unknown” unit will go on _____ and the “Given” unit will go on the ___________ of the ratio.
conversion
units
ratio
equivalent 60 60 7 7 1 1
top
bottom

8. If your units did not ________ ______ correctly, you’ve messed up!
How to Use Dimensional Analysis to Solve Conversion Problems
Step 1: Identify the “________”. This is typically the only number given in the problem. This is your starting point. Write it down! Then write “x _________”. This will be the first conversion factor ratio.
Step 2: Identify the “____________”. This is what are you trying to figure out.
Step 3: Identify the ____________ _________. Sometimes you will simply be given them in the problem ahead of time.
Step 4: By using these conversion factors, begin planning a solution to convert from the given to the unknown.
Step 5: When your conversion factors are set up, __________ all the numbers on top of your ratios, and ____________ by all the numbers on bottom.
Given
Unknown
conversion factors
multiply
divide
If your units did not ________ ______ correctly, you’ve messed up!
cancel out

9. How many hours are there in 3.25 days?
Practice Problems:
How many hours are there in 3.25 days?
(2) How many yards are there in 504 inches?
(3) How many days are there in 26,748 seconds?
24 hrs
3.25 days
78 hrs x =
1 day
1 ft
1 yard
504 in.
14 yards x x =
12 in.
3 ft
1 min
1 hr
1 day
26,748 sec
days x x x =
60 sec
60 min
24 hrs

10. Converting Complex Units
A complex unit is a measurement with a unit in the _____________ and ______________.
*Example: 55 miles/hour meters/sec g/mL
To convert complex units, simply follow the same procedure as before by converting the units on ______ first. Then convert the units on __________ next.
Practice Problems: (1) The speed of sound is about 330 meters/sec. What is the speed of sound in units of miles/hour? (1609 m = 1 mile)
(2) The density of water is 1.0 g/mL. What is the density of water in units of lbs/gallon? (2.2 lbs = 1 kg) (3.78 L = 1 gal)
numerator
denominator
top
bottom
330m
1 mile
3600 sec
738 miles/hr x x =
sec
1609 m
1 hr
1.0 g
1 kg
2.2 lbs
1000 mL
3.78 L
8.3 lbs/gal x x x x = mL
1000 g
1 kg
1 L
1 gal