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Calculating the overall change or energy in a reaction
KEy question: How can we calculate how much energy is given out in a reaction?
KEy question: How can we calculate how much energy is given out in a reaction?
Task 1 - Intro video
Task 1 - Intro video
Watch the video and answer the introduction questions in task 1 of the companion sheet
Task 2 - Recap
Task 2 - Recap
Work through the recap questions on slides 3 and 4 of the companion sheet
Task 3 - Bond energies
Task 3 - Bond energies
Here is a table of typical bond energies. It tells you the amount of energy, in KJ/mol, that it takes to break or make each individual bond.
Here is a table of typical bond energies. It tells you the amount of energy, in KJ/mol, that it takes to break or make each individual bond.
For example:
A single bond between 2 Carbon atoms takes 347 KJ/mol to break or make
A double bond between 2 Oxygen atoms takes 498 KJ/mol to break or make
You're will always be given one of these as part of a question in a GCSE, you do not need to memorise them!
You're will always be given one of these as part of a question in a GCSE, you do not need to memorise them!
Bond energies can be used to calculate the TOTAL energy of a reaction.
Bond energies can be used to calculate the TOTAL energy of a reaction.
This is the difference between the energy put in when bonds are broken and the energy given out when bonds are made.
This is the difference between the energy put in when bonds are broken and the energy given out when bonds are made.
Complete task 3 on the companion sheet slides 6, 7 and 8
Task 4 - prActise
Task 4 - prActise
Work you way through the practise questions on slides 9-12
You may use the internet to research the molecule formulas. For example Ethanol is C2H5.
Write out the Balanced equation
Use scrap paper to draw out the structural formula
Work out the energy need to break the bonds of the reactants
Work out the energy needed make the bonds of the products
Work out the overall change in energy - is it endo or exothermic?
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