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