Topic 14 - Particle model Flashcards
Describe the arrangement of solids?
Strong force of attraction hold the particles close together in a fixed, regular arrangement. The particles dont have much energy in their kinetic energy stores to they only vibrate about their fixed positions
Describe the arrangement of liquids?
Forces of attraction between particles are weaker (than solids) The particles are close together but can move past each other and form irregular arrangements. They have more energy than solids so they move in random directions at low speeds
Describe the arrangement of gases?
There are almost no forces of attraction between the particles. Particles have the most energy in their kinetic energy stores and therefore, are free to move in random directions at high speeds
Recall the density equation
Density = mass / volume
Describe how to measure the density of an object that isnt a regular shape
- Measure mass (m1) of an object using a mass balance
- Fill a bottle with a liquid of known density
- Place the stopper into the bottle and dry the outside
- Measure mass of bottle (m2)
- Empty the bottle and place object into bottle. Repeat steps 2 and 3 then measure the mass of the bottle (m3)
- Calculate volume of displaced water by finding out mass of displaced water (m2 - (m3 - m1) and dividing it by density of water
- Calculate density of the object with the mass measured in step 1 and the volume measured in step 6
The energy in a substance’s thermal energy store is held by its particles in their ……
Kinetic energy stores
What happens when you boil a liquid?
The extra energy transferred into the particles kinetic energy stores makes them move faster. Until the attraction holding the particles together is broken and bubbles of gas form in the liquid
What happens when you melt a solid?
The extra energy makes the particles vibrate faster until eventually the forces between them are partly overcome and the particles start to move around
Is the mass of a substance affected when it changes state?
No, the mass stays the same as it is only the particles that are being rearranged
What happens to density when a substance changes shape?
Volume changes as particles become further/closer together. If volume changes, then density must change too.
Generally, out of the three states of matter, which ones are the most/least dense?
Most dense - solids
Least dense - gases
What is a substances ‘specific heat capacity’?
The change in energy in the substances thermal store needed to raise the temperature of 1kg of that substance by 1 degrees. e.g. water has a specific heat capacity of 4200 J/kg
What is the relationship between temperature and energy?
Heating a substance increases the energy in its thermal energy store
in kinetic theory, Temperature is a way of measuring ….
The average internal energy of a substance
What is the equation relating energy, mass, specific heat capacity, and temp
Change in thermal energy = mass * SHC * Temperature change
Describe how to find the SHC of water?
1) Use a mass balance to measure the mass of the insulating container
2) Fill the container with water and measure mass again. The difference in mass is the mass of the water in the container
3) connect joulemeter to container (place lid on container)
4) Measure temp of water, then turn on power
5) When temp has increased by 10 degrees, stop experiment and record energy on joulemeter and increase in temp
5) Calculate SHC by rearranging equation (repeat experiment 3 times and then find mean of SHC)
Describe an experiment that shows temperature doesnt go down until all of a substance changes state whilst they are e.g. condensing
- Fill a beaker with crushed ice
2, Place a thermometer in the beaker and record temp - Gradually heat the beaker with a bunsen burner
- Every 20 secs, record temp and current state of ice
- Continue process until water begins to boil
- Plot a temp against time graph