2.4 Density Calculations

• Natuurkunde / Scheikunde
• Middelbare school
• vwo
• Leerjaar 2

Density Calculations

Which answer is false?
Density is:

1. property of a substance
2. volume/mass
3. mass/volume
4. mass in grams of substance per cubic centimetre

Remember?

density = mass/ volume

mass (m) in grams (g)

volume (V) in cubic centimetre (cm³)

density (p) in grams per cubic centimetre (g/cm³)

mass

1 kg = 1000 g

1 g = 1000 mg

40 mg = 0.04 g

kg --> g (x 1000)

mg --> g ( divide by 1000)

Volume

1 dm3 = 1000 cm³

1 L = 1000 mL 

40 mL = 0.04 L

L --> mL (x 1000)

mL --> L (divide by 1000)

1 mL = 1 cm³

1 L = 1 dm³

Question

Calculate the density

Use G.A.F.C.A

G = given

A= Asked

F= Formula

C = Calculation

A = Answer

Answer

G: m = 200 g

l = 6 cm; w = 4 cm; h = 5 cm

A: density

F: density = mass/volume

C: V = l*w*h= 6 x 4 x 5 = 120cm³

density = 200 g / 120 cm3

A: density = 1.7 g/cm3

Calculate the density

Answer

G: mass = 324 g

l = 4 cm; w = 3 cm; h = 10 cm

A: density

F: density = mass/volume

C: V needs to be calculated first: V = l*w*h

V = 4 x 3 x 10 = 120 cm³

density = 324 g/ 120 cm3 = 2.7 g/cm³

A: The density of the block is 2.7 g/cm³

The label of a bottle of syrup says:
0.75L | 850 g
What is the density of the syrup?

Answer

G. m = 850 g; V = 0.75 L

A. density

F. density = mass / volume

C. V = 0.75 L ; you have to convert this to cm³

V = 0.75 L = 750 mL = 750 cm³

density= 850 g/ 750 cm³

A. density = 1.13 g/cm³

Question

Lisa has a rock and wants to determine the density. She uses a measuring cilinder. She starts with 50 mL water in the cilinder. After adding the rock, the water has risen to 58 mL.

The mass of the rock is 40 gram.

Calculate the density.

Answer

G. Vbegin = 50 mL; Vend = 58 mL

m = 40 g

A. density

F. density = mass / volume

C. You have to find V first: V = Vend - Vbegin

V = 58 mL - 50 mL = 8 mL   8mL = 8 cm³

density = m / V = 40 g / 8 cm³ 

density = 5 g/cm³