Heat Changes ( 14.1 ) Flashcards
how can you measure the amount of energy released
by measuring the temperature change in water
explain the measuring variables method in the combustion of alcohol experiment
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
what is used to minimise heat loss in the combustion of alcohol experiment
use draft insulators to minimise heat loss
what is used to heat the glass
heat energy is used to heat the glass
what practical considerations must be considered
some of the water may evaporate
what is the equation for enthalpy change
heat energy transferred = mass x specific heat capacity x temperature change
what is the unit for mass
g
what is the unit for specific heat energy
c
what is the unit for temperature change
degrees celsius
what is the unit for heat energy transferred
J/g degrees celsius
what is the equation for moles
moles = mass / Mr
what’s the equation for molar enthalpy change
molar enthalpy change = heat transfer / moles
what’s the symbol for molar enthalpy change
Delta H ( Triangle H )
what’s the symbol for temperature change
Delta T ( Triangle T )
give the steps in working out the molar enthalpy change
1) work out the enthalpy change
2) calculate the number of moles
3) divide the number of moles by the heat energy transfer
