Can somebody please tell me in what I should do in this question and how to work it out and also explain

what the difference is when it says "excess" or not being excess.

 

thanks

Sorry, but we don't do people's homework for them. Do you know what a limiting reagent is? If not, I suggest you start by looking that up.

Sorry, but we don't do people's homework for them. Do you know what a limiting reagent is? If not, I suggest you start by looking that up.

I don't really want somebody to do it for me but explain what I should do and think about

Okay, so you have two reactions in this to consider. The first is the reaction of the aluminium compound, which you know to consist of Al and C.

 

The second reaction you should recognise as a combustion reaction. The products of this are CO2 and H2O. Where has the carbon and hydrogen come from in this? How do you think you can use that information to work out how much carbon (in grams and then in moles) was in the aluminium compound?

 

The part of the question that states that one of your reagents is in excess just means that you have more of it than you need for all of the other reagent to be consumed. It is related to limiting reagents, etc., but it's not strictly relevant to answering your question.