Combustion

Question 1

what is required for a fuel to undergo combustion

Answer 1

the fuel, oxygen and energy to initiate the reactions (Ea)

Question 2

combustion

Answer 2

an oxidation process, the carbon is oxidised/oxygen is added and the oxygen is reduced

Question 3

complete combustion

Answer 3

combustion that occurs when there is an excess of oxygen

Question 4

reaction for combustion

Answer 4

Fuel + O2 (g) = CO2 (g) + H2O (l/g)

Question 5

incomplete combustion

Answer 5

occurs when there is a limited amoubt of oxygen, hence less energy is released as the oxidation process is incomplete

Question 6

incomplete combustion reaction

Answer 6

Fuel + O2 (g) = CO (g) + H2O (l/g)

Question 7

heat of combustion

Answer 7

the amount of heat energy released in an exothermic combustion reaction when a specified amlunt of substance is burned completely in oxygen

Question 8

heat of combustion symbol

Answer 8

ΔHc

Question 9

how does ΔHc compare to ΔH

Answer 9

it is the same however ΔHc is always negative as it is only used to describe combustion reactions which always release heat

Question 10

equation to calculate heat of combustion

Answer 10

ΔHc = energy/moles

Question 11

equation to caculate enthalpy

Answer 11

ΔH = Energy/moles

Question 12

equation to calculate energy from known enthaply or heat of combustion

Answer 12

energy = ΔH or ΔHc X moles

Question 13

thermochemical equation

Answer 13

a chemical equation that also includes the value of enthalpy change, it shows the energy absorbed or released

Question 14

heat of combustion units

Answer 14

KJ mol-1

Question 15

how to calculate heat of combustion fromn known enthalpy

Answer 15

ΔH/n

Question 16

when we reverse a reaction what happens to enthalpy

Answer 16

it is the same but switches from negative to positive or vice versa