Required activity 9: Titration curves

Chemistry practicals

Why do meters need to be calibrated

pH meters can lose accuracy on storage

What is used for the calibration of a pH meter

a set buffer with a known pH (often pH 4)

Give a way of increasing the accuracy when constructing a pH curve

Maintaining a constant temperature

When carrying out the method that allows you to construct a pH curve alkali eventually should be added until it is in what state

excess

What should be done through out to equalise the pH of the mixture

stir

What action should be taken when reaching the end point of a titration

add alkali/ substance in smaller amounts

On a curve what is the equivalence point of a strong acid/strong base reaction

7

On a curve what is the start point of a strong acid/strong base reaction

\~1

On a curve what is the end point of a strong acid/strong base reaction

\~13

With a weak acid and a strong base the ph rises quickly and levels off. What is the flattened part of the curve called and why

buffer region, a buffer solution is formed

On a curve what is the equivalence point of a weak acid/strong base reaction

> >7

On a curve what is the start point of a weak acid/strong base reaction

3

At ½ the neutralisation volume the \[HA\] =

\[A-\]

If we know the Ka we can then work out the pH at ___ or vice versa.

½ V

If a pH curve is plotted then the pH of a weak acid at half neutralisation(½ V) will equal the ___

pKa

In a strong acid weak base what is the equivalence point

what is different about the curve for a weak acid/ weak base compared to other titration curves

No Steep part of the curve

Strong acid example

HCl

Weak base example

NH3

Strong base example

NaOH

Weak acid example

CH3CO2H