Memorisation Flashcards
Which of the states of matter can be compressed?
Gas
What is the equation for density?
density=mass/volume
What is the name for the equipment we use to work out an objects volume?
A displacement can
What is specific heat capacity?
the amount of energy needed to raise 1kg of a substance by 1 degree C
What is specific latent heat?
the amount of energy needed to change the state of 1kg of a substance
Which is higher, the specific heat capacity or the specific latent heat for a substance?
Specific latent heat
Which is higher, the specific latent heat of melting or the specific latent heat of evaporation?
specific latent heat of evaporation
When a substance changes state, what happens to its temperature?
it stays the same (until all particles have changed state)
Why does increasing the temperature off a fixed volume of gas increase the pressure?
the particles collide with the sides more often with a greater force
How do you convert temperature in degrees Celcius to degrees Kelvin?
Add 273 to the degrees Celcius
Describe boiling
When heat is added, the particles move around faster and have enough energy to break the bonds altogether.
Describe condensation
If the temperature is lowered, particles will no longer be able to overcome forces of attraction, and the particles move closer together, and turn into a liquid.
How do you measure the density of a liquid?
Place an empty measuring cylinder onto a balance, then ‘zero’ the reading.
Add some of the liquid to the measuring cylinder.
Read the volume of the liquid from the measuring cylinder.
Read the mass of the liquid from the balance.
Use the density formula to calculate the density from the mass and volume measurements.
What is temperature?
a measure of the average kinetic energy of the particles in a substance.
What assumptions does the particle model make?
Particles are small, spherical and inelastic
Which state has the strongest forces of attraction and which has the weakest?
Strongest = solid weakest = gas
What is the formula for specific latent heat?
Specific latent heat = energy needed to change state / mass
What is the formula for specific heat capacity?
Change in thermal energy / (mass x change in temperature)
In a closed system will the mass change during a change in state?
No, the number of particles stays the same
How do you calculate the density of a solid?
Measure the mass of the solid using a balance.
If the shape is regular, measure the volume of the solid using geometry.
If the shape is irregular, measure the volume of the solid by adding it to a Eureka can filled with water. This will cause a volume of water exactly equal to the volume of the solid to flow into the measuring cylinder.
Use the formula to calculate the density of the solid from the mass and volume measurements.
Describe melting
As heat is added to a system, the particles vibrate more and more until they have enough energy to break free of their bonds. This allows the particles to move freely
How would a student determine the specific heat capacity of water?
1) Put a beaker on a balance and ‘zero’ the reading
2) Add water and record the mass from the balance
3) Put thermometer and immersion heater in water
4) Read starting temperature of water
5) Wrap beaker in insulating foam
6) Connect joulemeter and powerpack to immersion heater
7) Leave for 30 minutes
8) read total energy passed into immersion heater and final temperature
9) Calculate specific heat capacity
How would a student determine the change in temperature of ice as it melts?
1) Add crushed ice to boiling tube
2) Record temperature with thermometer
3) Place boiling tube into a beaker and then the beaker onto a tripod with a guaze
4) fill beaker with water to create a water bath when heater
5) light bunsen burner underneath tripod
6) record temperature of ice every minute as it melts and for a further 3 minutes after
7) note time when ice starts to melt and then once it is melted
8) draw a line graph
How would a student improve the accuracy of the specific heat capacity experiment?
Use an insulator to reduce energy transferred to surroundings, ensure immersion heater is fully submerged into water to make sure all energy passes into water, stir water to make sure thermal energy is spread out, use an electronic temperature probe to avoid human errors
What is the difference between a physical change and a chemical change?
During a physical change, no new substance is formed. This is reversible. However during a chemical change a new substance is formed. This is usually not reversible.
