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### Little Product

Posted: Sun Mar 04, 2018 9:15 pm
I was looking through my notes and in one of the lecture slides, it says that it is easier to study initial rate when very little product is present. Why is this the case?

### Re: Little Product

Posted: Sun Mar 04, 2018 9:36 pm
If product is present then it can influence the reaction rate. Hence, we study the initial rates (when little to no product has formed) so that we can ignore the effects of products on the reaction rate.

### Re: Little Product

Posted: Sun Mar 04, 2018 9:54 pm
When there is product present, the product will also be reacting to form reactant. So this reverse reaction would occur in addition to reactant forming product, changing the overall rate at which reactant is consumed and product is formed.

We therefore use initial rates to avoid having to calculate anything about the reverse reaction.

### Re: Little Product

Posted: Sun Mar 04, 2018 10:13 pm
For reactions with multiple reactants, we also tend to use a small amount of one reactant and excess of the other reactants in order to study the order of each reactant. For example, in a reaction A + B + C ====> D, we would use A and C in excess and a small amount of B to determine its order with respect to its concentration.

### Re: Little Product

Posted: Tue Mar 06, 2018 5:38 pm
This is why we study initial rates, because initially, there is little to no product and everything is in terms of the reactants. That's why for our differential rate law, the species in it are all for reactants.