How to prepare 50mM Na2HPO4/H3PO4 buffer, pH 4.5

[Natsu1993]

The have to prepare the buffer but I really don't know how. Is the any formula for the buffer preparation?

Ps. Sorry but one more thing, what does the "/" between Na2HPO4 and H3PO4 mean?

 

[Borek]

/ means buffer containing both Na₂HPO₄ and H₃PO₄.

I strongly suggest you start by reading about buffer solutions, for example here: https://en.wikipedia.org/wiki/Buffer_solution (but there are plenty of other resources on the web).

For pH 4.5 this is a very bad buffer choice.

Sorry to say that, but from the way you asked the question it is clear you are not qualified for the task.

 

[Natsu1993]

So, I have to prepare H3PO4 and then add NaOH?

H3PO4 + 2NaOH ---> Na2HPO4 + 2H2O

Am I correct?

 

[Borek]

This is one of ways of doing it. You can as well mix the acid and the salt solution.