[stevekim8]

hi. i'm doing a lab at school called "acid-base titration of an eggshell" lab. i have some questions.

1. what is definition of standardizing? (in chemistry definition)
2. why was excess acid added to the eggshell?
3. any possible sources of error and suggestions for improvement in the error?

i think this is the lab i did
http://science.csustan.edu/phillips/CHEM1102/egg.htm

please help me
thanks!

[Ch3micat]

1. Standardizing is getting a chemical that you know it's qualities.  In this case, probably, you prepared some NaOH (or maybe an acid) and by standardizing it, you should know what the molarity is.  This can be done by prepping an acid like KHP for example, from a solid, into a liquid, and then titrating it with the NaOH to figure out what the NaOH molarity is.  When you figure it out, the NaOH is standardized.

2. ? No idea.   To ensure an acidic environment perhaps?

3.  Inconsistent people reading burets, bad reading of burets, chemical residue left on instruments, innacurate/uncalibrated instruments, human error for anything subjective...  To fix these, have the same person read burets every time, use rubber policemen to push chemical residues out, properly calibrate instruments, buy better instruments etc.

[Borek]

Back titration.