Pre-University Chemistry

1. Chapter 2

3. 30°C 30°F

4. SI unit

6. English vs. Metric Units
Left Image: http://webapps.lsa.umich.edu/physics/demolab/controls/imagedemosm.aspx?picid=1167
Right Image: http://share.lancealan.com/N800%20ruler.jpg
Which is longer?
A. 1 mile or 1 kilometer
B. 1 yard or 1 meter
C. 1 inch or 1 centimeter
1.6 kilometers
1 mile
1 yard = 0.9444 meters
1 inch = 2.54 centimeters

7. Metric Units of Length
The basic unit of length in the metric system in the meter and is represented by a
lowercase m.
Metric Units
1 Kilometer (km) = 1000 meters
1 Meter = 100 Centimeters (cm)
1 Meter = 1000 Millimeters (mm)
Which is larger?
A. 1 meter or 105 centimeters
B. 4 kilometers or 4400 meters
C. 12 centimeters or 102 millimeters
D. 1200 millimeters or 1 meter

8. Measuring Length
How many millimeters are in 1 centimeter?
What is the length of the line in centimeters? _______cm
What is the length of the line in millimeters? _______mm
1 centimeter = 10 millimeters
What is the length of the line to the nearest centimeter? ________cm

9. English vs. Metric Units
Which is larger?
1. 1 Pound or 100 Grams
2. 1 Kilogram or 1 Pound
3. 1 Ounce or 1000 Milligrams
1 pound = 453.6 grams
1 kilogram =
2.2 pounds
1 ounce of gold =
28,349.5 milligrams

10. Metric Units of mass
Mass refers to the amount of matter in an object.
The base unit of mass in the metric system in the kilogram
and is represented by kg.
Metric Units
1 Kilogram (km) = 1000 Grams (g)
1 Gram (g) = 1000 Milligrams (mg)
Which is larger?
A. 1 kilogram or 1500 grams
B. 1200 milligrams or 1 gram
C. 12 milligrams or 12 kilograms
D. 4 kilograms or 4500 grams
Kilogram Prototype Image - http://en.wikipedia.org/wiki/Kilogram

11. English vs. Metric Units
Which is larger?
A. 1 liter or 1 gallon
B. 1 liter or 1 quart
C. 1 milliliter or 1 fluid ounce
1 gallon = 3.79 liters
It would take approximately 3 ¾
1-liter bottles to equal a gallon.
1 fl oz = 29.573 ml
1 12-oz can of soda
would equal
approximately 355 ml.
1 quart = 0.946 liters

12. Metric Units
Volume is the amount of space an object takes
up.
The base unit of volume in the metric system in
the liter and is represented by L or l.
Metric Units
1 liter (L) = 1000 milliliters (mL)
1 milliliter (mL) = 1 cm3 (or cc) = 1 gram*
Which is larger?
A. 1 liter or 1500 milliliters
B. 200 milliliters or 1.2 liters
C. 12 cm3 or 1.2 milliliters*

13. Measuring Volume
We will be using graduated cylinders to
find the volume of liquids and other objects.
Read the measurement based on the bottom of the
meniscus or curve. When using a real cylinder, make
sure you are eye-level with the level of the water.
What is the volume of water in the cylinder? _____mL
What causes the meniscus?
A concave meniscus occurs when the molecules of the liquid
attract those of the container. The glass attracts the water on
the sides.

14. Measuring Liquid Volume
Imagescreatedathttp://www.standards.dfes.gov.uk/primaryframework/downloads/SWF/measuring_cylinder.swf
What is the volume of water in each cylinder?
Pay attention to the scales for each cylinder.

15. Measuring Solid Volume
10 cm
9 cm
8 cm
We can measure the volume of regular object
using the formula length x width x height.
_____ X _____ X _____ = _____
http://resources.edb.gov.hk/~s1sci/R_S1Science/sp/e
n/syllabus/unit14/new/testingmain1.htm
We can measure the volume of
irregular object using water displacement.
Amount of H2O with object = ______
About of H2O without object = ______
Difference = Volume = ______

16.  How hot? How cold?
 direction of HeatTransfer
 Celsius – 0 0C Freezing Point ofWater
100 0C Boiling Point ofWater
 Kelvin = C° + 273
 No degree signs are used
 O Kelvin = -273.150 C
▪ coldest possible temperature

17.  Length – size
 meter (m)
 Mass – amount of matter
 Kilogram (kg) or gram (g)
 Volume – space something takes up
 Liter (l) or centimeters cubed (cm3)
 Temperature – amount of heat
 Kelvin (K) = celsius + 273

18.  Measure of how much matter is squeezed
into a given space
 density = mass
volume

19.  A block of wood and a block of steel have the
same volume

20.  What happens to the density of an object if it
is cut into pieces?
 Which has the greater density, a single
uranium atom or Earth?

21.  coefficient x 10 raised to a power
 Single gram of hydrogen
 602,000,000,000,000,000,000,000 molecules =
 6.02 x 1023 molecules
 Mass of an atom of gold
 0.000000000000000000000327 grams =
 3.27 x 10-22 grams

22.  36,000
 3.6 x 104
 503,000,000
 5.03 x 108
 0.00076
 7.6 x 10-4

23. The valid digits of a number
In measurement: includes all of the digits that
are known, plus a last digit that is estimated

24.  Significant:
 nonzero digits
 final zeros after the decimal points
 zeros between two other significant digits
 Not significant
 zeros used solely for spacing the decimal point are
not significant.

25.  each have only two sig figs
 0.0071 meter
 0.42 meter
 0.000099 meter
 7.1 x 10-3 meter
 4.2 x 10-1 meter
 9.9 x 10-5 meter

26. Value
5.60
5.6
0.012
0.0012003
0.0120
0.0012
# of significant figures
3
2
2
5
3
2

27. If the digit immediately to the right of the last
significant digit is less than 5, it is dropped
 5 or greater - last significant digit increased by 1
 41.58 square meters  41.6 square meters

28.  Round 65.145 meters to 4 sig figs
 65.15m
 Round 100.1°C to 1 sig fig
 100°C
 Round 154 cm to 2 sig figs
 150
 Round 0.000718 kilograms to 2 sig figs
 0.00072

29.  Counting
 Example: 23 people in the classroom
▪ (Not 22.9 or 23.1) 23.00000000……………….
 Exactly defined quantities
 Example: 60 minutes = 1 hour
▪ 60.00000000……………………..

30.  calculated answer cannot be too precise
 not more precise than the least precise measurement
 Multiplication and Division
 same number of sig figs as the measurement with
the least number of sig figs
 Addition and Subtraction
 same number of decimal places as the measurement
with the least number of decimal places

31.  Accuracy
 How close a
measurement
comes to the actual
value of what is
being measured
 Precision
 How close a series of
measurements are
to one another

32.  Difference between accepted value and
experimental value
 error = experimental value – accepted value
 % error = x 100%error
accepted value

33.  % error = x 100%
99.1°C – 100.0°C x 100%
100.0°C
0.9°C x 100%
100.0°C
0.9%
error
accepted value
=
=
=