Section 5- Soilds, Liguids and Gases P2 Flashcards
What are the differences between particles of the same state?
the arrangement and energy of the particles are different
What theory can explain the three states of matter?
Kinetic theory
What are the properties of particles in a solid?
- strong forces of attraction between the particles
- particles close together in a fixed, regular arrangement
- particles don’t have much energy so only vibrate about their fixed positions
What are the properties of particles in a liquid?
- weaker forces of attraction between particles
- particles are close together, but can move past each other, form irregular arrangements
- more energy than solid particles
- move in random directions at low speeds
What are the properties of particles in a gas?
- almost no forces of attraction between them
- particles have more energy than liquids and solids
- free to move particles, travel in random directions at high speeds
What is the thermal energy store of a substance?
The energy in a substance’s thermal energy store is held by its particles in their kinetic energy stores.
When you heat a liquid what happens to the particles?
- the extra energy is transferred to the particles’ kinetic energy stores, making them move faster
- eventually, when enough of the particles have enough energy to overcome their attraction to each other
- bubbles of gas form in the liquid(this is boiling)
When a substance is melting or boiling what happens to the energy you input?
-the energy is used for breaking intermolecular bonds rather than raising the temperature, so a substance stays at a constant temperature
When a substance is condensing or freezing what happens to the substance when it is at the point of changing state?
- bonds are forming between particles, which releases energy
- the temperature doesn’t go down until all of the substance has changed state
What is evaporation?
Evaporation is when particles escape from a liquid and become gas particles
Why is evaporation a special example of changing states?
Particles can evaporate from a liquid at temperatures that are much lower than the liquids boiling point.
What are the conditions by which evaporation can occur?
- if the particles are travelling in the right direction to escape the liquid
- if the particles are travelling fast enough(have enough kinetic stores), overcome the attractive forces of the other particles in the liquid
What is the effect to the energy of the particles when particles leave the liquid and evaporate?
- the fastest particles with the most energy are most likely to evaporate
- when they evaporate the average speed and temperature of the remaining particles decrease
- the liquid cools as a result
How can the cooling effect of evaporation be useful?
You sweat when you exercise or get hot
-as the water on your skin evaporates, you cool down`
Describe a practical for how to obtain a temperature-time graph for water?
- fill a beaker with crushed ice, place a thermometer in and record the temperature
- use a Bunsen burner to heat the ice
- every 20secs record the temperature and the current state of the ice, continue until the water boils
- plot a graph of temperature against time
How should a graph look for the heating of ice to steam?
- proportionally increasing to 0°C where it levels
- then increases again to 100°C where it levels
- then increases
What is another name for the thermal energy store of a substance?
the internal energy of a substance
Is there a difference in the amount of energy required to increase the temperature of different materials.
Yes
- need 4200J of energy per kg of water to raise 1°C
- need 139J of energy per kg of mercury to raise 1°C
What is the equation for working out the specific heat capacity?
𐤃Q = m x c x 𐤃T 𐤃Q (change in thermal energy J) m (mass kg) c (specific heat capacity J/kg°C) 𐤃T (change in temperature °C)
Describe a practical for how to find the specific heat capacity of water?
- use a mass balance to find the mass of the water (taring the container first) (use an insulated container)
- record the temp of the liquid
- heat the liquid and use a joulemeter to find out how many joules are given off for the temperature to increase by 10°C
- use the specific heat capacity equation
- repeat at least 3 times
How can you measure the specific heat capacity of a solid?
- the block must have two holes, for the heater and thermometer
- wrap the solid in an insulated layer
- once you’ve heated by a set amount and recorded the joules on the joulemeter
- wait until the temperature stops increasing before recording the highest temperature
