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| The buret filled with NaOH |
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| KPH |
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| KHP solution ready to be titrated |
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| The solution turns pink where the base hits it, but then soon disappears |
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| The endpoint has been reached! |
Thursday, February 4, 2016
Titration Lab
This week, we've been working on a new lab. The purpose of the lab is to standardize a solution of NaOH with KHP, and then, use that solution's molarity to determine the percentage of acetic acid is in vinegar. To start, we filled the buret with NaOH, and measured out some KHP on a weigh boat. We transfered the KHP to a flask, and filled it with water to make a solution of 75 mL. Next, we added three drops of phenolphthalein to act as a color indicator for the endpoint. Lastly, we slowly drained the NaOH solution into the flask until the solution reached a permanent pink color. This was the hard part as we never knew exactly when to stop, but then again, we couldn't go too slowly as we needed to finish within a class period. Although, I thought I sometimes went too overboard with the NaOH, we ended up getting a 0.85% error! All in all, I enjoyed this lab and watching the clear liquid turn into a bright pink in a matter of drops.
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My lab partner and I also had problems getting the right amount of NaOH added so as not to turn it bright pink. Unfortunately, we came out with around a 5% error, but congratulations on your percent error. Also, congratulations on spelling phenolphthalein right!
ReplyDeleteI agree with both of you. I was happy that there is a picture of my hand up there. Also, great job explaining the lab, Erin. I really didn't talk about the procedure in my lab post, but you did. And I really was happy that we got a 0.85% error. I usually screw up big time in labs.
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