# Units of Measurement

Topics: International System of Units, Temperature, Kilogram Pages: 4 (569 words) Published: October 2, 2008
Units of Measurement: Sections 1.4-1.5

Physical QualityName of UnitAbbreviation
MassKilogramKg
LengthMeterm
TimeSecondsª (Sec)
TemperatureKelvinK
Amount of SubstanceMolemol

Système International d’Unitès (used in the science community world wide) •Uses different base unit for quantity

Velocity m/s (two base units build velocity = derived unit) {g/sec, kg/min}

Metric System

PrefixAbbreviationMeaning
MegaM106
Kilok103
Centic10-2
Millim10-3
Microµ10-6
Nanon10-9
Picop10-12

Volume

Most common used metric u nits for volume: Liter (L), milliliter (mL), 1dm3 = 1L A liter is a cube 1 dm long on each side
1cm3 = 1mL A milliliter is a cube 1 cm long on each side

Uncertainty in Measurements

Different measuring devices have different uses and degrees of accuracy. Some examples are of these devices are:

Syringe
Buret
Pipet

Temperature

Measure of average kinetic energy of particles in a sample
Kelvic Scale (purely scientific)
Celsius Scale (scientific)
Farenheit Scale (U.S. Only)

Molecules and atoms become unstable at Absolute zero.
No negative temperatures of Kelvins
Celsius scale is based on properties of water
0° is the freezing point of water

The Kelvin is the SI unit of temperature.
It is based on the properties of gases

K + °C + 273.15

The farenheit scale is not used in scientific measurements
°F = 1.8(°C) + 32
°C = 0.56 (°F-32)

Density

Physical property of a substance d = m/v [g/mL, kg/L, kg/m3, g/cm3] •The formula for density is Mass per unit volume d = m/v

Significant Figures

Digits that were measured (sig figs)
When rounding calculated numbers, we pay attention to significant figures so we do not overstate the accuracy of our answers. •All nonzero digits are significant
Zeros between two...