p1.2.2 energy and temperature

Question 1

what is temperature?

Answer 1

is a measure of the average kinetic energy of a substance particles, measured in degrees Celsius or kelvin

Question 2

what is energy?

Answer 2

is the measure of the total thermal energy stored in an object measured in joules

Question 3

what physical changes happen when a solid is heated?

Answer 3

particles gain more energy and they move more and their temperature increases

particles undergo a change of state e.g. melting or boiling

Question 4

what chemical change happens when a solid is heated?

Answer 4

a reaction is triggered and different molecules are formed

Question 5

what’s a physical change?

Answer 5

the change is reversible like changes of state e.g. filtering sand from water

Question 6

what’s a chemical change?

Answer 6

the reaction is irreversible and a new substance is formed e.g. forming new salts

Question 7

why is baking a cake a chemical reaction?

Answer 7

because you cannot change it to the way it was and the cake is now a new substance that has been foermed

Question 8

why is melting chocolate a physical reaction?

Answer 8

because it can be returned to its former state by freezing and the particles undergoes a change of state e.g. melting

Question 9

during a state change, what happens to the temperature of a substance?

Answer 9

it remains constant

Question 10

why is energy being used in a state of change?

Answer 10

it is used to break (heating) or make (cooling) intermolecular bonds

Question 11

cooling curve of steric acid

Answer 11

liquid

              physical change
                                              

                                                solid

Question 12

what are factors that will affect the amount of heat required?

Answer 12

the type of material
the mass of material
the temperature

Question 13

what is specific heat capacity?

Answer 13

the specific heat capacity of a material is the amount of heat required to raise the temperature of 1kg of a material by 1’c

Question 14

what is the equation for change in thermal energy?

Answer 14

mass x specific heat capacity x temperature change

Question 15

what is the equation for mass?

Answer 15

change in thermal energy / specific heat capacity x temperature change

Question 16

what is the equation for temperature change?

Answer 16

thermal energy / specific heat capacity x mass

Question 17

what is the equation for specific heat capacity?

Answer 17

change in energy / mass x temperature change

Question 18

what is the unit for thermal energy?

Answer 18

j- joules

Question 19

what is the unit for mass?

Answer 19

kg- kilograms

Question 20

what is the unit for specific heat capacity?

Answer 20

j, ‘c, KJ-kilojoules

Question 21

what is the unit for temperature change?

Answer 21

‘c

Question 22

exam question-
water has a specific heat capacity of 4200 j/kg/’c 2kg of water is to be heated by 20’c calculate the energy required

Answer 22

16800j

Question 23

what happens when a hot object and a cold object are left in a room?

Answer 23

hot objects get colder and cold objects get warmer until they reach thermal equilibrium- same temperature

Question 24

what is specific latent heat?

Answer 24

the amount of energy required to change the state of 1 kg of material without a change in the temperature

Question 25

what is the equation for thermal energy for a change of state?

Answer 25

mass x specific latent heat

Question 26

what is the equation for mass?

Answer 26

energy / specific latent heat

Question 27

what is the equation for specific latent heat?

Answer 27

energy/ mass

Question 28

what is thermal energy for a change of state used for?

Answer 28

to break intermolecular forces between the atoms

Question 29

what's the difference between specific heat of melting and specific latent heat of boiling?

Answer 29

specific latent heat of melting applies to the energy required to melt 1kg of a material and of boiling applies to energy required to boil 1kg of a material

Question 30

explain why the pressure of a balloon increases when more particles are blown into

Answer 30

gas pressure is caused when a gas particle collides with a surface and exerts a force onto it increasing the number of collisions on the balloons surface which increases the pressure and makes the balloon expands

Question 31

what type of energy do gas particles get more of when heated?

Answer 31

thermal and kinetic

Question 32

what is pressure?

Answer 32

pressure is the force per unit area it is measured in pascals

Question 33

what would happen if pressure was reduced to zero?

Answer 33

the temperature reaches a minimum

Question 34

what is the coldest possible temperature?

Answer 34

absolute zero

Question 35

what happens when the temperature is absolute zero?

Answer 35

the particles have no internal energy and do not move