Density

Density: The amount of matter that occupies a certain space.It is the mass per unit

volume of a substance.

What is Density? Densities of Common Elements and Compounds

 Substance Density

grams per mL or cc

 Water 1.00

 Aluminum, Al

 2.70

 Iron, Fe  7.80

 Gold, Au  19.30

 Mercury, Hg  13.5

1. Lead is much more dense than iron. So given the same volume of each, lead will weigh more (have more mass).

2. Ice (solid) is less dense than water (liquid). Therefore ice floats on water

Let’s look at Examples of Density:

Frozen Ice

Liquid Water

Almost all chemical compounds are least dense in the gas form and increase in density towards the solid form.

(Most dense) Solid Liquid Gas (Least dense)

Water densities:Gas = Least denseLiquid = Most denseSolid = Less dense than liquid (in water only!)

Water is a Chemical Exception!

To calculate density you need two things: Mass and VolumeD = densityM = mass V = volume

Can have several different units:kg/lg/mlg/cm3

Calculating Density

D = M V

A softball has a mass of 360 g and a volume of 270 cm3. Find its density.

Given: Mass = 360 gVolume = 270 cm3

Required:

Density (in g/cm3)Answer :

D = M/V = 360 g / 270 cm3 = 1.33 g/cm3

Example

https://www.youtube.com/watch?v=ijj58xD5fDI

Displacement

We measured the volume of a piece of copper by displacement in a beaker of water. The initial volume of water was 21ml and after placing our piece of copper into the beaker, the new volume was 26ml. Calculate the density this piece of copper weighing 53.47g. (remember density = mass / volume)Mass = 53.47gVolume = 26 ml-21 ml = 5 mlDensity = 53.47 g = 10.694 g/ml

5 mlA pen has what density?

Example

Mass Volume Density

25 g 40 mL

280 kg 1.5 m3

77 mg 1.5 mL

2.0 mL 1.5 g/mL

50 g 25 g/L

250 mg 1.0 mg mL

55 L 4 kg/L

3.0 L 0.0025 g/ L

75 kg 200L

200 L 50 g/L

290 g 75 mL

50 g 55 g/mL

200 L 4.0 mg/L

1500 kg 4 000 000 kg/m3

48 g 250 cm3

Worksheet – How Much? How Dense?

Answer KeyMass Volume Density

25 g 40 mL 0.63 g/mL

280 kg 1.5 m3 187 kg/m3

77 mg 1.5 mL 51 mg/mL

3.0 g 2.0 mL 1.5 g/mL

50 g 2.0 L 25 g/L

250 mg 250 mL 1.0 mg mL

220 kg 55 L 4 kg/L

0.0075 g 3.0 L 0.0025 g/ L

75 kg 200L 0.38 kg/L

10 000 g 200 L 50 g/L

290 g 75 mL 3.9 g/mL

50 g 0.91 mL 55 g/mL

800 mg 200 L 4.0 mg/L

1500 kg 0.00038 m3 4 000 000 kg/m3

48 g 250 cm3 0.19 g/cm3

You are going to determine the density of 6 different objects. (4 provided, 2 you provide)

Step 1: Find the mass of your object using the electronic scale (in grams and to 2 decimal places)

Step 2: We will be using water displacement to calculate volume.Submerge the object in a graduated cylinder filled

with water and note the volume change.Volume of object = final volume after

displacement – initial volume before displacement.Step 3: Calculate density.

Density Activity; It’s Dense!

Object Mass (g)

Volume (mL) Density (g/mL)

1. Bronze coloured cube

7.29 g VI = 19 mLVF = 20 mLVF-VI = 20-19 = 1 mL

D=M = 7.29g V 1 mL

7.29 g/mL

2.

3.

4.

5.

6.

Construct the following table:You must show all your calculations!

Classification of Matter

Matter: Anything that has mass and takes up space.

Mixture: Two or more substances mixed together.

Pure Substance: A substance that contains only one kind of matter.

Mechanical Mixture: A mixture of two or more components that can be seen with the unaided eye.

Classification of Matter

Solutions: A homogeneous mixture of two or more substances.Heterogeneous: Consisting of elements

that aren’t all the same (variability).Homogeneous: Uniform (the same)

throughout.Precipitate: The formation of a solid in a

solution during a chemical reaction.