CHEMISTRY SCIENTIFIC MEASUREMENTS

The standard units of measurement

SI (International System)

Qualitative

What something is

Quantitative

How Much?

Quantity

Something that can be measured

Examples of quantity

•Money

•Time

Unit

How it is measured

Examples of Unit

•Money

•Height

•Feet, inches, meters

Quantity symbol of Length

l

Base unit of Length

Meter

Unit abbreviation of length

m

Quantity symbol of mass

m

Base unit of mass

Kilogram

Unit abbreviation of mass

Kg

Quantity symbol of Time

t

Base unit of time

second

Unit abbreviation of time

s

Quantity symbol of Temperature

T

Base unit of Temperature

Kelvin

Unit abbreviation of Temperature

K

Quantity symbol of Amount

n

Base unit of Amount

Mole

Unit abbrevation of Amount

mol

The difference between mass andd weight

•Mass is constant

•Weight= Mass * Gravity

Converting SI metric units table

International System unit of volume

m³

International System unit of liquids and gases

Liters (L)

1cm^{3 =}

1mL

Mass per unit of volume / Density

How heavy something is compared to its volume

Density formula

D = m/v

Density for solids

g / cm³

Density for liquids

g / mL

Density of gases

g / L

Scientific notation formula

M x 10ⁿ

Accuracy

Closeness to actual value

Precision

Consistence of measurements

Precent error formula

([Actual value - Lab value] / Actual Value) x 100

Factors affecting measurement quality

• Human error

• Contamination

• Equipment

Buoyant Force

The force exerted by a fluid on an object

Greater density =

More buoyant force

Object is more dense than fluid

Object sinks