Mole equation....
Mass / mr
Mass (interm of moles) equation...
Moles x mr
Concentration equation...
Mass / volume
Mass (interm of concentration) equation...
Concentration x volume
Oxygen gas test result
Glowing splint relights
Hydrogen gas test result
Lit splint makes a squeaky pop
Carbon dioxide gas test result
Limewater turns cloudy
Chlorine test result
Damp litmus paper turns white
Example of an exothermic number
Any negative number
Example of an endothermic number
Any positive number
In an endothermic reaction is the energy released when bonds are formed more or less than the energy needed to break the bonds?
Less
In an exothermic reaction is the energy released when bonds are formed more or less than the energy needed to break the bonds?
More
Bond energy calculation unit of final answer...
KJ/mol
Enthalpy (energy) change calculation...
Bonds broken - bonds made
Calculate the enthalpy change when water is formed from H² and O²
. Add the bond enthalpy of all the bonds broken
Eg. H-H ×2 = 2×436 = 872
O=O ×1 = 1×498 = 498
872 + 498 = 1370
. Add the bond enthalpy of all the bonds made
Eg. O-H ×4 = 4×464 = 1856
. Calculate enthalpy change
Eg. 1370 - 1856 = -486
. Explain why a reaction is exothermic or endothermic
Eg. This is a negative sign meaning it's exothermic
Why is a reaction exothermic?
A reaction is exothemic because the energy released when bonds are formed is more than the energy needed to break the bonds
. Why is a reaction endothermic?
A reaction is endothermic because the energy released when the bond are formed is less than the energy needed to break the bonds