The endpoint of the neutralization titrations was determined, by measuring the pH value and observing the colour change, with six different indicators. Using measurements and computer models I calculated the titration errors and plotted them on different titration curves. The measurements of the acid-base titrations largely agree with the theoretical facts. The most frequent errors are personal, instrumental, random and method errors. Personal errors are colour blindness, incorrect reading of volumes from burettes or pipettes. Instrumental errors include contaminated inventory and improper use of glassware. Methodological errors include incorrect selection of indicators and the use of contaminated chemicals. Random errors are caused by changes in laboratory humidity, temperature or light. Errors were more significant in titrations with weekly acids and bases than in titrations where I used stronger acids and bases. We can influence and minimize some errors, but some are not due to the human factor and we have no influence on them.
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