·
Make sure you know the definitions below as they are easy marks to get in AS/A-level Chemistry exam! 👩🏫
Definitions
- Hess's Law
The enthalpy change is independent of the path taken.
- Bond Enthalpy
The energy required to break 1 mole of gaseous bonds to form gaseous atoms.
- Standard Enthalpy Change of Combustion
The enthalpy change when 1 mole of a substance undergoes complete combustion in its standard state.
- Standard Enthalpy Change of Formation
The enthalpy change when 1 mole of a compound is formed in its standard state from its elements in their standard states.
Enthalpy Calculations procedures:
- See what value you have to find
- Write the correct equation for the change
- See what data is provided
- Select the method of calculation which uses the data and apply Hess's Law
- Check the sign and units for ΔH
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4936730/846173_989284.png)
Reference:
https://getrevising.co.uk/files/documents/enthalpy_summary/enth.pdf
This is the end of the topic!
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4936730/509322_411619.png)
Drafted by Cherry (Chemistry)