Units of Measurement Meter m Liter L Celsius C. Mass is the amount of matter, weight is a measure of the gravitational pull on matter.

Units of MeasurementMeter m

Liter L

Celsius C

Mass is the amount of matter, weight is a measure of the gravitational pull on matter

SI UnitsPrefix Symbol Scientific

notationFactor Example

Mega M 1 x 106 1,000,000 megagram (Mg)

Kilo k 1 x 103 1,000 kilometer (km)

Hecto h 1 x 102 100 hectoliter (hL)

Deka da or (D) 1 x 101 10 dekagram (Dg)

BASE UNIT 1 x 100 1 meter

Deci d 1 x 10-1 .1 deciliter (dL)

Centi c 1 x 10-2 .01 centimeter (cm)

Milli m 1 x 10-3 .001 milligram (mg)

Micro u 1 x 10-6 .000001 microgram (ug)

Nano n 1 x 10-9 .000000001 nanometer (nm)

Pico p 1 x 10-12 .000000000001 picogram (pg)

PracticeIn each pair below, circle the larger

Millimeter Centimeter

picometer Micrometer

kilogram Hectogram

deciliter millileter

Basic SI UnitsQuantity Base unit

Length meter (m)

Mass gram (g)

Time second (s)

Volume Liter (L)

Temperature Kelvin (K) or Celsius (C)

Amount of substance mole (mol)

Heat & Energy joule (J)

Metric Conversion

1.) 3.45 cm= Dm

king henry Died by drinking chocolate milkK h D base d c m

0.00345

243.52.) 2.435 g= cg

2.35

3.) 23.8 mL= L

4.) 14.8 km= m

5.) 23.5 cg= dg

0.0238

14800

TemperatureUse both the Kelvin and Celsius scale, to convert

Celsius + 273 = Kelvin

Kelvin -273 = Celsius

373 K = °C

20°C = K293

100

Volume: measured in cubic centimeters (cm3) or liters

• 1 liter (L) = 1 cubic decimeter (dm3) = 1000 millileters (mL)• 1 mL= 1 cm3

• Volume can be measure by Length x x or the Water Displacement method

width height

• Volume can be measure by Length x width x height or the Water Displacement method

Know the relationship between the following volume units…

L = mL = cm3 (or cc in medical lingo) 1 1000 1000

Density

• Is the ratio of mass per unit of volume. How much matter is packed into a given amount of space

• Density = mass ÷ volume

• D= M V

• The Density of a substance stays regardless of the size of the sample. For example: if you cut a block of copper in half, you have decreased both the mass and volume, the ratio of the 2 stays the same. This is called an Intensive Physical Property.

Constant

• The appropriate units of density are:

• for solids• for liquids

g/cm3

g/mL

Example problems:

• A sample of aluminum metal has a mass of 8.4g. The volume of the sample is 3.1 cm3. Calculate the Density of aluminum.

D = M =V

8.4 3.1

=2.7 g/cm3 2 sig figs

Example problems:

• Diamond has a density of 3.26 g/cm3. What is the mass of a diamond that has a volume of 0.350 cm3?

D = 3.26 g/cm3

M = ? V = 0.350 cm3

D = M V

3.26 g/cm3 x 0.350 cm3 = 1.14 g3 sig figs

Example problems:

• What is the volume of a sample of liquid mercury that has a mass of 76.2 g, given that the density of mercury is 13.6 g/mL?

V = ? M = 76.2 g D = 13.6 g/mL

D= MV

76.2 g 13.3 g/mL = 5.7293 mL = 5.73 mL

Reliable Measurements

• refers to the closeness of the measure value is to the , or real, value.

• refers to how a series of measurements are to one another.

Accuracy

Actual

Precision Close

• is calculated by subtracting the value from the value.

ErrorExperimental accepted

• The is the ratio of an error to an accepted value.

percent error

% error = error x 100 = accepted value – experimental value x 100 accepted value accepted value

Example

• An experiment finds the density of lead to be 10.95 g/cm3. The literature value for the density of lead is 13.34 g/cm3.

The error: accepted value – experimental value=

• 13.34 – 10.95 =

An experiment finds the density of lead to be 10.95 g/cm3. The literature value for the density of lead is 13.34 g/cm3.

2.39

The error: accepted value – experimental value=• 13.34 – 10.95 = 2.39

The % error: error x 100 % = accepted value

2.39 x 100 % =13.34

17.9 %

Practice

• Sara’s lab shows the atomic mass of aluminum to be 28.9. What is her percent error if the accepted value is 27.0?

28.9 – 27.0 = 1.90

7.04%1.90/27.0 x 100% =

Practice

• What is the percent error in a measurement of the boiling point of bromine if the textbook value is 60.8 °C and the lab value is 40.6 °C?

60.8 °C – 40.6 °C = 20.2 °C

20.2 °C / 60.8 °C x 100% = 33.2%