Standard conditions are 100 kPa, which is 1 atmospheres and 298K, which is 25°C although in liquids it is a concentration of 1 mol dm-3
What is the correct definition of exothermic?
A reaction in which the enthalpy of the products is smaller than the enthalpy of the reactants, resulting in heat loss to the surroundings.
A reaction in which the enthalpy of the products is greater than the enthalpy of the reactants, resulting in heat being taken in from the surroundings.
What is the ΔH of an endothermic reaction?
Negative
Positive
What kind of reaction is exothermic?
Combustion
Photosynthesis
Select all the examples of endothermic reactions
Thermal Decomposition
Respiration
The equation for the complete combustion of methane is CH4(g) + 1.5O2(g) -->CO(g) + 2H2O(l)
The energy from photosynthesis comes from the light of the sun
Is the enthalpy profile diagram exothermic or endothermic?
Exothermic
Endothermic
Is this enthalpy profile diagram exothermic or endothermic?
Activation energy is the minimum energy required to start a reaction by the breaking of bonds.
When a liquid the standard conditions are a concentration of 2.0 mol dm-3
What is the correct definition of activation energy?
The minimum energy required to start a reaction by the breaking of bonds
The maximum energy required to start a reaction by the formation of bonds
Which is the correct equation for working out the heat exchange during a reaction?
Q=mcΔT
n=c*V/1000
In Q=mcΔT, c is the specific heat capacity of the surroundings
Select all the products formed in the complete combustion for CH4
CO2
H20
2H20
CO
The ΔH of a combustion of C3H7OH is -1881 kJ mol-1, what type of reaction is it?
Bond enthalpy is the enthalpy change that takes place when breaking by homolytic fission 1 mol of a given bond in the molecules of a gaseous species
Which of the following is the correct explanation for breaking and making bonds?
Breaking bonds requires energy and is endothermic, making bonds releases energy and is exothermic
Breaking bonds releases energy and is endothermic, making bonds requires energy and is exothermic
Hess's law states that if a reaction can take place by more than one route and the initial and final conditions are the same, the total enthalpy change is the same for each route
An enthalpy cycle shows what?
Only one route between the reactants and products so does not allow the indirect determination of an enthalpy change
The alternative routes between reactants and products which allows the indirect determination of an enthalpy change from other known enthalpy changes using Hess' Law
Which of these are factors that affect the rate of reaction?
Temperature
Pressure, when the reactants are gases
Concentration
Surface Area
The addition of a catalyst
When is the rate of reaction at its highest?
At the start
During the reaction
When one of the reactants has been used up
When one of the reactants has been used up the reaction continues
A catalyst slows down a reaction and is used up in the process
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