add more notes on energy (already studied in 2k18)

diff --git a/chem/energy.md b/chem/energy.md
index c532be18f05c8efaec8c2e0c6fbd163850167a14..30a6df1f892512beb810f698994ddfe7abed4bab 100644 (file)
--- a/chem/energy.md
+++ b/chem/energy.md
@@ -9,8 +9,22 @@ $$\Delta H = H_{\text{products}} - H_{\text{reactants}}$$
 
 Must specify states (latent heat)
 
 
 Must specify states (latent heat)
 

+## Thermochemical equations
+
+$\Delta H$ notates energy change (i.e. kJ / mol)  
+Exothermic - negative $\Delta H$
+

 ## Calorimetry
 
 $$E = mc \Delta T$$
 
 ## Calorimetry
 
 $$E = mc \Delta T$$
 

-$$\text{calibration factor} = {E \over \Delta T} = {VIt \over \Delta T} \quad \text{J/K}$$
\ No newline at end of file
+$$\text{calibration factor} = {E \over \Delta T} = {VIt \over \Delta T} \quad \text{J/K}$$
+
+## Fuels
+
+Substance used for energy production by **combustion** (exothermic)  
+Fossil fuels - decaying organic material (e.g. coal, petrol, nat. gas)
+
+### Efficiency
+
+$$\text{% efficiency} = {\text{energy obtained in desired form} \over \text{energy available before conversion}} \times 100$$
\ No newline at end of file