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Chemistry help!! pH curves

Hey,
I was doing some questions on this topic and am slightly confused.
The question is regarding pH curves.

The acid and base are both of equal concentrations.

25cm^3 of acid is measured into a conical flask, and a base is added from a burette. The question gives data about the pH of the solution as the base is being added, so I plot a graph of pH against "volume of base added". The point where the curve is vertical is the equivalnce point, which should be at 25cm^3 as 25cm^3 of acid is in the conical flask, but my graph shows it at 24.5cm^3. And a lot of the calculations I did, used the value of 24.5. Is this wrong and should I have used 25, or is it ok.

Thanks :smile:

Reply 1

Hippysnake

The base maybe slightly more concentrated than the acid, even though you said they're equal.

Or, could have been some sort of measuring/equipment error.

Reply 2

zafaru123

Hippysnake

The base maybe slightly more concentrated than the acid, even though you said they're equal.

Or, could have been some sort of measuring/equipment error.

You're probably right, since some of the later questions were about accuracy. I'm hoping the mark scheme allows students to use the value according to the graph I sketched.

Thanks.