DENSITY NOTES Mass – the measure (amount) of matter in an object. Units – grams (g)

Density Notes Volume – the amount of space that an object occupies. Units – cm 3 (cubic objects) Units – ml (irregular objects)

DENSITY Density is mass per volume of a material. Density = mass divided by volume. D = m/v

SET-UP M D V

FINDING MASS 1.) Measure using a calibrated triple beam balance. 2.) Set the object on pan. (chemicals – do not touch.)

Mass Cont. 3.) Move 100 g rider until arm falls, then move rider back 1 notch. 4.) Do the same with the 10 g rider. 5.) Balance with 1 g rider.

Mass Cont. 6.) Tap with pencil to be sure its balanced. 7.) Measure to the 100 th of gram. (2 decimal places).

Finding Volume Measure Volume in 2 ways: –1.) Metric Ruler/ shape: regular objects. (ex. Blocks) –Formula: l x w x h –Unit: cm 3

Volume –2.) Graduated Cylinder Shape: irregular objects. (ex. Paper clip, rock) Unit: mL

Finding Volume Meniscus When you place an object in water, the water level rises. Process: DISPLACEMENT.

Example A student places 100 mL of water in a graduated cylinder. Student drops a rock into cylinder with water. The new level reads 120 mL What is the volume?

Answer ANSWER 20 mL

COMPUTING DENSITY D = m/v Density = mass/volume

UNITS FOR DENSITY Regular objects: g/cm 3 Irregular objects: g/mL

Density Important #’s to Remember Density of water: 1 g/mL Why important?

Density If an object sinks = density higher than 1 g/mL. If an object floats = density lower than 1 g/mL. Ice Floats

Density When an object is heated it expands.

EXAMPLES Volume Before Heating: v = 4 mL m = 16 g D = 4 g/mL

EXAMPLES CONT. Volume after Heating: V = 8 mL m = 16 g D = 2 g/mL

Relationship Volume increases = Density decrease Volume decreases = Density increases