The International System of Measurement

(SI)

SI

System of measurement used world wide

Makes communication between countries, languages and different measurement systems easy, consistent

Uniformed – everyone is “speaking the same language”

Base Quantities

Base Units Symbol

Length Meter m

Mass Gram g

Volume Liter l

Temperature Celsius C

Prefixes

Used to change the size of the value

Used in front of the base unit

Used to make large numbers smaller and smaller numbers larger

Does not change the value itself

Common Prefixes

Prefix Symbol ValuePower of

10

kilo- k- 1000 103

hecto- h- 100 102

deca- da- 10 101

Base unit g,l,m 1 100

deci- d- 1/10 10-1

centi- c- 1/100 10-2

milli- m- 1/1000 10-3

Unit ConversionsUsed to change from one sized unit to another

Value does not change only the size of the unit

ex: 1 dollar = 100 pennies = 20 nickels =

10 dimes = 4 quarters

Value ($1) remains the same, just the size of the unit changes

Tools of Measurement

Equipment used to measure mass, length, volume and temperature

Each tools measures in its own unit

The smaller the unit the more accurate the measurement

Tools of measurement (con’t)

Base Quantities

Tools Units

Mass Balance Grams

VolumeGraduated Cylinder

milliliters

Length Metric ruler cm/m

Temperature thermometer ºC

C. Derived UnitsCombination of base units.

Volume - length length length

1 cm3 = 1 mL 1 dm3 = 1 L

Density - mass per unit volume (g/cm3)

D = MV D

M

V

D. DensityAn object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass.

GIVEN:

V = 825 cm3

D = 13.6 g/cm3

M = ?

WORK:

M = DV

M = (13.6 g/cm3)(825cm3)

M = 11,220 g

DM

V

D. Density1) A liquid has a density of 0.87 g/mL. What

volume is occupied by 25 g of the liquid?

GIVEN:

D = 0.87 g/mL

V = ?

M = 25 g

DM

V

WORK:

V = M D

V = 25 g

0.87 g/mL

V = 28.7 mL

D. Density2) You have a sample with a mass of 620 g & a

volume of 753 cm3. Find density.

GIVEN:

M = 620 g

V = 753 cm3

D = ?

DM

V

WORK:

D = M V

D = 620 g

753 cm3

D = 0.82 g/cm3