2.4 Density

Which answer is false?

Density is:

1. property of a matter
2. volume/mass
3. mass/volume
4. amount 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 (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 = 10,000 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

Work with

G.

A.

S.

Answer

G. m = 200 g

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

A. density

S. density = m/V

V = l*w*h= 6 x 4 x 5 = 120 cm3

density = 200 g / 120 cm3

density = 1,7 g/cm3

All answers checked?

Tuesday 31 Octobre

Little Test 2.3 and 2.4 in MRTS-hour

Practise:

Calculate the density

Answer

Given: m = 324 g

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

Ask: density

Solution: density = m/V

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

Question

The label of a bottle of cordial says:

0.75L | 850 g

What is the density of the cordial?

Answer

G. m = 850 g; V = 0.75 L

A. density

S. density = m/V

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

V = 0.75 L = 750 mL = 750 cm3

density= 850 g/ 750 cm3

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

S. density = m/V

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