Heat Changes ( 14.1 )

Question 1

how can you measure the amount of energy released

Answer 1

by measuring the temperature change in water

Question 2

explain the measuring variables method in the combustion of alcohol experiment

Answer 2

1) measure the mass of the alcohol and burner before and after combusting the fuel
2) the temperature of the water can be measured before and after to find the temperature change
3) divide the temperature change by the mass of fuel used and compare to the mass needed to heat the water up by 1 degree

Question 3

what is used to minimise heat loss in the combustion of alcohol experiment

Answer 3

use draft insulators to minimise heat loss

Question 4

what is used to heat the glass

Answer 4

heat energy is used to heat the glass

Question 5

what practical considerations must be considered

Answer 5

some of the water may evaporate

Question 6

what is the equation for enthalpy change

Answer 6

heat energy transferred = mass x specific heat capacity x temperature change

Question 7

what is the unit for mass

Answer 7

g

Question 8

what is the unit for specific heat energy

Answer 8

c

Question 9

what is the unit for temperature change

Answer 9

degrees celsius

Question 10

what is the unit for heat energy transferred

Answer 10

J/g degrees celsius

Question 11

what is the equation for moles

Answer 11

moles = mass / Mr

Question 12

what’s the equation for molar enthalpy change

Answer 12

molar enthalpy change = heat transfer / moles

Question 13

what’s the symbol for molar enthalpy change

Answer 13

Delta H ( Triangle H )

Question 14

what’s the symbol for temperature change

Answer 14

Delta T ( Triangle T )

Question 15

give the steps in working out the molar enthalpy change

Answer 15

1) work out the enthalpy change
2) calculate the number of moles
3) divide the number of moles by the heat energy transfer