Hello,
I have a little problem. I try to find out why the second equation in the picture is correct. How can I get it? Down on the paper is what I did.

Where did the (1+V2/V1) disappear from the right side of equation?

Thank You for every help.

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Borek
Mentor
In general you are right, something is wrong. Perhaps V2 is much lower than V1, then 1+V2/V1 is approximately 1.

In general you are right, something is wrong. Perhaps V2 is much lower than V1, then 1+V2/V1 is approximately 1.
Thank You sir. I really appreciate your help.

mjc123
Homework Helper
The clue is in the title of the post. Equation 1 is about mixing two solutions; Equation 2 is about adding pure B to a solution. There is no V2 and c2; n2 moles of pure B are added to solution 1. The assumption is that this does not result in any change to the volume V1 of the solution, which is a good approximation if c1 and c3 are both dilute.

Borek
The clue is in the title of the post. Equation 1 is about mixing two solutions; Equation 2 is about adding pure B to a solution. There is no V2 and c2; n2 moles of pure B are added to solution 1. The assumption is that this does not result in any change to the volume V1 of the solution, which is a good approximation if c1 and c3 are both dilute.
I understand what you want to tell me but can I ask something?

Why by adding pure B the volume does not change?

mjc123