1. Units of measurement
Chapter 2
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2. Measurements are quantitative information.
Measurement represents quantities
Quantity= something that has magnitude, size, or amount.
A quantity is not the same as measurements
Ex: the quantity represented by a teaspoon is volume. (the teaspoon is a unit of measurement, while volume is a quantity)
Almost,  every measurements is a number plus a unit.
The choice of unit depends on the quantity being measured.

3. SI Measurement Le Système International d'Unités
This system was adopted in 1960 by the General Conference on Weights and measures.
SI has seven base units.

5. Length Shorter distances (cm) SI standard unit is meter
Km is used to express long distances
Ex: road signs
Shorter distances (cm)

6. Mass Mass is a measure of the quantity of matter. Mass vs Weight
SI standard unit for mass is Kg.
Mass vs Weight
Mass is determined by comparing the mass of an object with a set of standard masses that are part of the balance.
Weight is a measure of the gravitational pull on matter . (spring)
As the force of Earth's gravity  on an object increases so does its weight.

7. Volume: amount of space occupied by an object
The most commonly used metric units for volume are the liter (L) and the milliliter (mL).
A liter is a cube 1 dm long on each side.
A milliliter is a cube 1 cm long on each side.
1 m = 10 dm
(1 m)3 = (10 dm)3
1 m3 = 1000 dm3 or
0.001 m3 = 1 dm3
1 dm = 10 cm
(1 dm)3 = (10 cm)3
1 dm3 = 1000 cm3
0.001 dm3 = 1 cm3
These are conversion factors
1 m = 10 dm = 100 cm
Incidentally, 1 m3 = 1x106 cm3

8. Density
Another physical property of a substance – the amount of mass per unit volume.
Density does not have an assigned SI unit – it’s a combination of mass and volume.
density is temperature-sensitive, because the volume that a sample occupies can change with temperature. 
Densities are often given with the temperature at which they were measured.  If not, assume a temperature of about 25oC.

9. Sample Problem A
A sample of aluminum metal has a mass of 8.4 g. the volume of the sample is 3.1cm3 . What is the density of aluminum?
Diamond has a density of 3.26 g/cm3 .what is the mass of diamond that has a volume of 0.351cm3 ?
what is the volume of a sample of liquid mercury that has a mass of 76.2g , given that the density of mercury is 13.6g/mL?

10. Dimensional analysis
A mathematical technique that allows you to use units to solve problems involving measurements.
Quantity sought= quantity given x conversion factor