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First, we poured in solution no.1 into the titration flask, and added a few drops of phenolphtaleen (did i spell correctly), which turned the base into light purple colour.
Then, we poured in the acid into the pipette and fixed them onto the retort stand, and the experiment started.
We opened the pipette and drip a few drops of acid into the base. Our objective was to turn the base into colourless, a process called "neutralisation".
Drip...
Drip...
Drip...
We had used up to about 20ml of acid, and the base was still light purple in colour. Strange. Other groups only used up to about 12ml of acid for complete neutralisation, but we had finished almost 25ml and still no neutralisation. Immediately we smelled something "fishy".
Oh my God, we couldn't differentiate both solution! Which one was acid? Which one was base? We couldn't really sure. So we cheated (it's only practice, right?) by using the phenolphtaleen to test which was the base. Wait, we didn't used the wrong acid and base. What was WRONG HERE?
Looks like we used too much phenolphtaleen.
Oh man, we had to do the whole experiment again. We were way further away from others! Quick!
...
...
...
This time, we didn't confused which was acid and which was base. We actually wrote down solution no.1 (KA1) and solution no.2 (KA2) ON THE TABLE beside the beaker. (Okay okay, I know it's wrong, but what to do? Haha...)
Luckily we finished our experiment without making another mistake. Hey man, we were the second fastest to finish!
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That was strange, given that we had to restart our experiment all over again in the beginning.
Chemistry practical wasn't as tough as I had thought it'd be.
Chemistry practicals are all about perfection. Even 1ml will make a difference.
ReplyDeleteShudn't you label your beakers after you get your solutions? Haha. And just 1,2 drops of phenophtalein is enough. Don't have to make it very very purplish. It's just a marker and it's accurate, even though with one drop.
That's because it changes colour according to the pH, no matter how much phenophtalein you put in ;)