Nature’s Chemistry #3: Energy From Fuels
No description yet. This curated deck is ready for daily study.
Card preview (14)
Why are alkanes and alcohols excellent fuels?
They release vast amounts of energy when they undergo combustion
Combustion of alkanes Alkane + oxygen ->
Carbon dioxide + water
Combustion of alkenes Alkene+ oxygen ->
Carbon dioxide + water
Combustion of cyclohexanes Cyclohexane + oxygen ->
Carbon dioxide + warwr
What makes some fuels better than others?
They release more energy during combustion reactions
Negative sign
Exothermix
No sign (positive)
Endothermic
Eh = cm Δt
Eh = energy released /kJ c = specific heat capacity of the water /4.18kJ kg-1 °C-1 m = mass of water heated /kg Δt = temperature change / °C
As well as water, what can heat be absorbed by?
Other substances
What happens if a Eh=cm Δt uses a substance other than water?
• This equation is still used, but c will not be 4.18 • the specific heat capacity of the substance being heated will be given in the question
What can more accurate values of the energy released when fuels undergo combustion be obtained using?
A bomb calorimeter
The design of the bomb calorimeter:
• reduces heat loss to the surroundings • reduces incomplete combustion
How might an energy from fuels experiment be made more accurate?
• a metal can for conductivity • draught shield to reduce energy lost to surroundings
Fuel
A substance which burns to release heat energy in a combustion reaction