A student needs to conduct a reaction that combines chemicals A and B to synthesize product AB . If we write this as a chemical equation it looks like: A+B→AB If this student combines 100 molecules of A and 100 molecules of B , the student obtains 100 molecules of AB . How many molecules of A would this student need to make 5000 molecules of AB ? (Assume the student had enough of molecule B to make 5000 molecules of AB .) Express your answer as an integer.

Law of conservation of mass : It states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.

The given balanced chemical reaction is,

[tex]A+B\rightarrow AB[/tex]

As per question, molecule B is an excess reagent because it had enough molecule to make 5000 molecules of AB. So, molecule A is limiting reagent.

From the balanced reaction, we conclude that

As, 1 molecule of AB produced from 1 molecule of A

So, 5000 molecule of AB produced from 5000 molecule of A

Hence, the number of molecules of A needed to make 5000 molecules of AB will be, 5000