Particle model of matter Flashcards
Why is it incorrect to say iron is heavier than wood?
It depends how much iron and wood you have. You should say iron is denser than wood.
Water has a density of 1000 kg/m3. A piece of rubber has a density of 1024 kg/m3. Explain what would happen if the rubber was put in a pool of water?
Rubber has a higher density than water so the rubber would sink in water.
his “ready-mix” concrete waggon contains 9600 kg of concrete. If the density of the concrete is 2400 kg/m3, what volume of concrete does the waggon contain?
Mass/density
9600/2400 = 4
4m3
A sheet of insulating foam measures 3 m x 1 m x 0.08 m. It has a mass of 9.6 kg. Calculate the density of the insulating foam
V = 3 x 1 x 0.08 = 0.24 m3 Density = 9.6 / 0.24 = 40 kg/m3
High density foam is made of the same material and can be used to give better insulation for the same thickness of foam. Describe
how the arrangement of particles would differ in these two types of foam (you may draw diagrams to help your answer).
Particles in the high density foam will be closer together so there
are more particles in a given volume, making it denser.
When copper metal is heated to 1100 oC it melts.
Is this a chemical or physical change? Explain your answer.
Physical change. No new products have been formed.
What will happen to the mass of the sample of copper after it has melted? Explain your answer.
It will stay the same. Mass is conserved when state changes.
Explain the difference between a physical and a chemical change.
In a physical change no new products are formed and it can be easily reversed.
In a chemical change a new substance is formed which can not easily be changed back .
If you wanted to find the density of a brass key, you first need to measure its volume. Describe how to determine the volume of a brass key.
Drop the key into a known volume of water and
measure the amount of water displaced by the key.
This will be the volume of the key.
Define internal energy?
The total kinetic and potential energy of all the particles within a system
Which of the following will change the internal energy of a stone?
A. Lifting it to the top of a building
B. Heating it
C. Firing it from a catapult
Heating it.
Water and the chemical isooctane both boil at 100 oC. When the same amount of each substance is placed on a heater, the
isooctane boils first. Explain why this happens.
Isooctane has a lower specific heat capacity than water so less heat energy is needed to raise its temperature to its boiling point.
A hot stone is placed into a glass of water containing 200 g of cold water. If the stone transfers 25 200 J of energy to the water, what will the temperature rise of the water be? Specific heat capacity of water = 4200 J/kg oC
ΔE = m c Δθ
Temperature rise of the water = 30 oC
What is latent heat?
The energy needed to change the state of a substance without changing the temperature.
Explain the difference between latent heat of fusion and latent heat of
vaporisation.
Latent heat of fusion is the energy needed to change between solid and liquid. Latent heat of vaporisation is the energy needed to change state between liquid and gas.
