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Unformatted text preview: Q) Which weighs more:
A kilogram of feathers or a kilogram of iron? DENSITY
GEL2007 What is Density?
What If you take the same volume of different substances, then they will weigh different amounts.
Wood Water Iron 1 cm3 1 cm3 1 cm3 0.50 g 1.00 g 8.00 g IRON Q) Which has the greatest mass and therefore the most dense? Density is the Mass per unit Volume Density Equation:
g or kg Density = Mass
Volume m gcm3 or kgm3
cm3 or kg3 ρ = m V
V = m = 0.25 = 0.000250m3 ρ 1000
V = m = 0.25 = 0.000272m3 ρ 920 Example: ρ V Q) Liquid water has a density of 1000kgm3, while ice has density of 920kgm3. Calculate the volume occupied by 0.25kg of each. DENSITY OF A REGULAR SOLID
DENSITY
m = 240 g
2.0 cm ρ = m = 240 =10.0 g/cm3
3.0 cm V 24 4.0 cm Find the Mass of the solid on a balance. Measure the three lengths and calculate the Volume.
(ie V = l x w x h ) Calculate the Density. Material
Material Mass Length Width Height Volume Density in g in cm in cm in cm in cm3 in g/cm3 DENSITY
DENSITY Aluminium g/cm3
2.70 Iron 7.86 Brass 8.50 Wood
Slate 0.50
2.80 Glass 2.50 Lead
Marble
Wax 11.3
2.70
0.89 DENSITY OF AN IRREGULAR
SOLID
SOLID m = 360 g 80 cm3 50 cm3 ρ = m = 360 =12.0 g/cm3 V 30 Find the Mass of the solid on a balance.
Fill the Measuring Cylinder with Water to a known Volume. Add the Object. Work out the Volume of Water that is displaced. Calculate the Density. DENSITY OF AN IRREGULAR
SOLID
SOLID OR use a Eureka Can to find the Volume. Find the mass of the solid on m = 440 g 40.0 cm3 ρ = m = 440 =11.0 g/cm3 V 40 a balance.
Add water until just overflowing. Place a Measuring Cylinder under the spout. Add the Object. Collect the Water and read off the Volume.
Calculate Density DENSITY
DENSITY g/cm3 Aluminium 2.70 Iron 7.86 Brass 8.50 Wood 0.50 Slate 2.90 Glass 2.50 Mass of Liquid = Mass of Measuring Cylinder and Liquid – Mass of DENSITY OF A LIQUID
DENSITY empty Measuring Cylinder 45.0 g
25.0 g 20.0 cm3 45 – 25 = 20 g Find the Mass of an empty Measuring Cylinder.
Add a certain Volume of Liquid.
Find the Mass of the Measuring Cylinder and Liquid
Calculate the Mass of Liquid.
How?
Calculate Density of Liquid.
ρ = m = 20 =1.00 g/cm3 V 20 Liquid
Liquid Mass of empty Measuring Cylinder Mass of Measuring Cylinder and Liquid in g in g Mass of Liquid
in g Volume Density in cm3 in g/cm3 DENSITY OF A GAS
DENSITY To vacuum flask 150.0 g
170.0 g 1000 cm3 170 150 = 20.0g
ρ = m = 20 =0.0200 g/cm3 V 1000 Remove the air from a flask of a known Volume, using a vacuum pump.
Find its Mass.
Add the gas to be tested.
Reweigh.
The difference is the Mass of gas.
Calculate Density. ...
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 Winter '09
 RICHARDVANFLEET
 Mass

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