Changes of State

Question 1

What is the equation for change in thermal energy?

Answer 1

change in thermal energy = mass x specific heat capacity x change in temp
∆Q = m x c x ∆T

Question 2

Why does a heating system change the energy stored within the system and raise its temp or produce changes of state?

Answer 2

the energy in a substances thermal energy store is held by particles in their kinetic energy stores and hone you heat a substance the extra energy is transferred into the particles kinetic energy stores (moves faster) and break their bonds (liquids form bubbles of gas, solids overcome forces between).
when a substance is melting/boiling the enrages used for breaking intermolecular bonds than temp raise (so it stays as constant temp)

Question 3

What changes occur when a solid goes to a liquid, liquid to a gas?

Answer 3

when a substance is melting/boiling the enrages used for breaking intermolecular bonds than temp raise (so it stays as constant temp)
when you heat liquid extra energy is transferred into the particles kinetic energy stores (moves faster) and overcome attraction forming bubbles of gas
when you heat a solid the energy makes the particles vibrate faster until they overcome the forces holding them together and move around

Question 4

Describe the arrangement and motion of gases, liquids and solids

Answer 4

gases - spread out, no forces of attraction, free to move (no fixed positions) and move with rapid and random motion
liquids - tightly packed, irregular arrangements w weaker forces of attraction (no fixed positions)
solids - strong forces of attraction, close together in fixed, regular positions and only vibrate around fixed positions

Question 5

Describe an experiment to investigate temperature during a change of state

Answer 5

bunsen burner + water/tube with naphthalene and bung of wool, heated.
water is heated continuously (water temp rises until water boils and then remains constant), temp of solid (naphthalene) rises until it starts to melt (temp remains constant and then will rise again). during any change of state the temp will remain constant

Question 6

What is specific heat capacity?

Answer 6

energy required to change the temperature of an object by one degree Celsius per kilogram of mass (J/kg degrees celsius)

Question 7

Describe an experiment to investigate the specific heat capacity of materials

Answer 7

1. use mass balance to measure mass of insulating container 2. fill container w water and measure mass again (difference in mass is mass of water) 3. connect joltmeter to electric immersion heater in water (and insulating container) w thermometer in, place lid and set voltmeter to 0 4. measure temp of water, turn on the power 5. when temp has increased by 10 degrees, switch off power and record temp increase and energy 6.calcultate specific heat capacity by rearranging equation 7. repeat 3 times and calculate average

Question 8

How can you change the experiment for heat capacity of materials for solid?

Answer 8

put 2 holes for heater and thermometer and wrap in insulating and wait until temp has stopped rising