DF1:2 Getting Energy From Fuels Flashcards
What is calorimetry used to work out?
The enthalpy change of combustion.
What happens in a calorimetry experiment of the combustion of fuels?
A fuel is burned to raise the temperature of water by a specific amount, and it’s weighed before and after to work out the mass of the fuel burned.
Where is the energy transferred in the combustion of fuels?
To the water but some is lost to the surroundings.
What does a lid on the beaker do in the combustion of fuels?
Prevents heat loss.
What does a wind shield do in the combustion of fuels?
Prevents a draught moving the flame.
How can energy transferred in calorimetry be calculated?
q=mc deltaT
What is the m in an energy transferred calculation and what are its units?
The mass of water or solution (g).
What is the c in an energy transferred calculation and what are its units?
The specific heat capacity of water (J/g/K).
What is the specific heat capacity of water?
4.18 J/g/K
What is the deltaT in an energy transferred calculation and what are its units?
The temperature change (K).
What is the q in an energy transferred calculation and what are its units?
The energy lost or gained which depends on whether it is exo or endo (J).
How do you work out the enthalpy change (kJ/mol) in calorimetry?
Calculate the energy transferred and divide it by the number of moles of the fuel.
What other calorimetry experiment can be used?
Determining the enthalpy change of neutralisation.
What is used in the enthalpy change of neutralisation experiment and why?
A polystyrene cup to prevent heat loss.
What happens in the enthalpy change of neutralisation experiment?
An acid is added to the cup and the temperature is measured every fixed period, an alkali is added, stirred and its temperature change is measured.
