Titrations

titration

A solution of known concentration is used to determine the concentration of another solution.

analyte or titrand

unknown concentration

Titrant

Known concentration and is added slowly to the titrand to reach the equivalence point.

Titrations

allow for the careful determination of how much of a reactant is required to reach the end point of the reaction

Buret

the glassware used to carefully measure out the added reactant

be certain the buret is

cleaned and conditioned before use

Buret steps:

1. select appropriate clamp

2. clamp buret to ring stand

3. confirm that stopcock is closed in horizontal position before filling buret

4. place waste beaker under buret

5. lower buret and clamp as much as possible (with opening to eye level)

6. use a funnel to fill buret

7. reach almost to the 0 mark

8. remove funnel and raise height of buret

9. all air bubbles must be removed by opening and closing the stopcock

10. record initial volume

11. check stopcock to make sure it is sealed and not leaking titrant

Most analyte solutions require the addition of

an indicator

Indicators

produce a change in the color of the solution when the end point of the reaction is reached

When nearing the expected end point

add titrant more slowly, drop by drop

Throughout adding the titrant

stir

When using an indicator the first flash of color shows

that the reaction is close to the endpoint

the end point of the titration has been reached

when the color change persists and is visible evenly throughout the solution even after stirring

titration color should be

pale, not intense

After end point has been reached,

record the end volume of titrant

Condition buret

3 times with the titrant

Always clean the buret

3 times with DI water

Never load to

the 0 mark

Always record the volume of titrant after

allowing the air bubbles to escape from the tip

Make sure any solid analyte is

fully dissolved and mixed

Always add a few drops of

an appropriate indicator

Always stir the solution

continuously

Slow the addition of titrant near

the calculated end point

End point has been reached once

the color change of the indicator persists throughout the solution

if the color change is intense

you added too much titrant