Can someone tell me why this is a good laboratory technique?

A chemist should wait 10-15 seconds after dispensing a volume of titrant before a reading is made. Explain why the “wait” is good laboratory technique.

Also, the color change at the endpoint of vinegar analysis should persist for 30 seconds. Explain why the time lapse is a good titration technique.

Thanks.

2 Answers

  • First wait = you are stirring or swirling the flask (or beaker). You are allowing the acid and base to react, ensuring that you have no “bubbles” of acid or base in the reaction vessel.

    Second wait = Air contains CO2 which forms carbonic acid in solution. THe longer you wait, the more CO2 is absorbed.

  • rxns take time to occur, over time a lot of the solution or w/e being titrated would have reacted with the titrant as u add more and more, lower concentration means a longer time for all of it to react

    when u get near the endpoint of the titration, you’ll see that a visible change would persist for a while before it goes back to looking like it did before titrant was added

    (a really long persistence of color means that there’s pretty much no reactant left)

    that’s a basic answer

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