[Kwami77]

My friend and I did a zinc and copper sulfate reaction.
He calculated an order of reaction of 1, a year ago
 I calculated an order of reaction of 2 (same reaction), a few days ago

How is this even possible? Can the same reaction have two different orders?

[Arkcon]

Show your work, in both cases, and see the differences in the calculation.

FWIW, although order of reaction is VERY important to students, it is a pretty tough thing to determine experimentally.  You have to be careful.

The definitions of first order and second order reactions can give you a hint to which is likely for this particular reaction.

Concentration can change the order, because it may interfere with out ability to determine it.  Doesn't really change it, just masks the result for us.

I hope you don't mind my answering your question, with more questions that you now have to work on.  That is what we do here.  That's specified in the  Forum Rules{click}.  You agreed to read and follow these rules as a condition of signing up for our forum, and they apply to you, whether you agree with them or not, or even if you're unaware of them.

For example:

How is this even possible? Can the same reaction have two different orders?

What sort of answer were you hoping to get from these questions.

[sjb]

In addition, and complementing Arkcon's reply take a look at https://chemistry.stackexchange.com/questions/81063/formation-of-hydrogen-bromide-does-the-concept-of-order-apply-to-this-reactio

Here it is suggested that differing concentrations affect the relative rates of reactions, and so the actual order of the reaction in question.

[Vidya]

May be one of you is wrong.

[Irlanur]

how would you even determine the concentration of Zink?