Year 12s: what will be the first way you research your future options? >>

How to work out the number of moles of reactants??

Idk if I'm stupid or whatever but I'm really confused. I know I need to do q/number of moles of reactants. And I know how to calculate the moles of each individual reactant but which one do I divide the q by??? Sometimes the question is specific like "the enthalpy change when one mole of ammonium nitrate dissolves) so I know I need to calculate 1 mole of ammonium nitrate (Mass/Mr) but there are other questions that say stuff like "calculate the enthalpy of neutralisation for this reaction" or "calculate the enthalpy of combustion" (assuming it means enthalpy change) and I can work out q but that's it. Am I meant to calculate the moles of the thing being used to burn or...? and no idea for neutralisation. THIS IS STRESSING ME OUT SO MUCH.

Reply 1

Proxenus

is there a question you could post that has this problem in it

Reply 2

bluemadhatter

Original post by Proxenus

is there a question you could post that has this problem in it

question 2. i kinda figured out that moles were 0.05 but there are 2 reactants so like what if they both had different moles :frown:

Reply 3

charco

Study Forum Helper

Original post by bluemadhatter

question 2. i kinda figured out that moles were 0.05 but there are 2 reactants so like what if they both had different moles :frown:

You need a balanced equation for the reaction and then you must see which is the limiting reagent. It is this one that gives you the moles of the final products.

Reply 4

bluemadhatter

Original post by charco

You need a balanced equation for the reaction and then you must see which is the limiting reagent. It is this one that gives you the moles of the final products.