I perform at least 4. 1 to get a rough reading and 3 for the average.
The results are usually within 1 mL of each other. The problem is that is a pretty big difference in molarity when calculating.
Errors add up very quickly. You should get to a range of titrant volumes used (for say 3 titrations) of within 0.1 - 0.2 ml (for about 20 - 25 ml
titrant used).
You need to:
1. use a decent Primary Standard
2. weigh to 1 mg or better
3. use Class A volumetric flasks for any sample or titrant preparation
4. use Class A volumetric pipettes
5. use a decent professional burette and make sure you read it properly (avoiding parallax errors)
6. familiarise yourself with end point determination
7. use a decent sized conical flask
8. make sure you titrate all of the sample: wash the walls of
your conical flask with small amounts of deionised water near the end point to make sure any splatter is accounted for
9. make sure you understand results calculations
Hmm well my scale could be the big issue besides the purity of the primary standard I am using. It can only read to .01g.
Can anyone recommend a good scale that has a readability of .001g that doesn't cost $500 USD?
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