Solids, liquids and gases New unit Solids, liquids and gases First lesson Density

DENSITY Q) Which weighs more:- A kilogram of feathers or a kilogram of iron? DENSITY Objective: To describe how to determine density using direct measurements of mass and volume

Density is the Mass per unit Volume What is Density? 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 Q) Which has the greatest mass and therefore the most dense? Density is the Mass per unit Volume

Density Equation: = m V m V  Mass Density = Volume Example: g or kg m V  Mass Density = Volume g/cm3 or kg/m3 cm3 or m3 = m V Example: Q) Liquid water has a density of 1.0g/cm3, while ice has density of 0.92g/cm3. Calculate the volume occupied by 250g of each. Vwater = m = 250 = 250cm3  1.0 Vice = m = 250 = 272cm3  0.92

DENSITY OF A REGULAR SOLID 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. m = 240 g 2.0 cm 3.0 cm 4.0 cm  = m = 240 =10.0 g/cm3 V 24

DENSITY OF AN IRREGULAR SOLID Find the Mass of the solid on a balance. Find the Volume. Calculate the Density.

Archimedes and the Crown                                                                                            Archimedes was a great scientist who lived more than 2000 years ago in a Greek city called Syracuse. He was very clever at inventing and figuring out how things work, so King Hiero needed his help many times.

Density of gold 20 g/cm3 1cm3 of gold has a mass of 20 g Density of silver 10 g/cm3 1cm3 of silver has a mass of 10 g For the same volume, gold has more mass Silver has to have a bigger volume to have an equal mass to gold The actual volume of the crown was 150cm3 instead of 100cm3. Was it pure gold ?? The mass of the crown was 2000g. It should have a volume of 100cm3

DENSITY OF AN IRREGULAR SOLID use a Eureka Can to find the Volume. Find the mass of the solid on 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 m = 440 g 40.0 cm3  = m = 440 =11.0 g/cm3 V 40

Carry out an experiment to measure the density of two regular and two irregular objects Material Mass in g Length in cm Width Height Volume in cm3 Density in g/cm3 Material Volume in cm3 Density in g/cm3 Irregular objects

Quiz

Which block X or Y has the greater mass? 5400 kg 2m3 7800 kg 1m3 X Y X

Which block X or Y has the greater volume? 5400 kg 2m3 7800 kg 1m3 X Y Y

Which block X or Y has the greater density? 5400 kg 2m3 7800 kg 1m3 X Y X

Density of Petrol = 800kg/m3 Density of water = 1000 kg/m3 Which has more mass 1m3 of petrol of 1m3 of water? 1m3 of water

Density of Petrol = 800kg/m3 Density of water = 1000 kg/m3 Which has more volume (takes up more space) 1kg of petrol of 1kg of water? 1kg of petrol

Last q The density of Aluminium is 2700kg/m3. what is the mass of 10m3 of Aluminium? = m V Mass = 2700 x 10 = 27000 kg

DENSITY Objective: To describe how to determine density using direct measurements of mass and volume. Homework: Read pages 10-11 in the textbook and answer the questions