Acid vs. Alkali
So today we learnt about cleavage in Chemistry. Apparently, salt crystals have cleavage. I think I'd better stay the heck away from table salt.
After the two Chemistry periods, I had my Chemistry practicals - in my two free periods! :(
We had to neutralize 25 ml of sodium hydroxide, an alkali with some amount of oxalic acid, measure the volume of acid we used and then do some calculations to find out what how concentrated the sodium hydroxide solution we used was.
We had to prepare the oxalic acid solution, individually, from the powder and make 250 ml of acid. In the first try, I made a little bit more than needed because the friggin' glass rod was blocking the funnel that led into the flask and the water just sat there in the funnel. I realized what had happened and I removed the glass rod, and whoosh! the water went pouring into the flask, way above the 250 ml mark. Fuck. I had to prepare the oxalic acid solution all over again.
After I made exactly 250 ml of acid, I had to shake the flask well so that the water and the acid would mix and the acid solution would be equally concentrated all through the flask. I shook it a bit and said, "Ah, it must all be equal now!" and set it down. Mistake.
My first titre [volume of acid needed to neutralize the definite volume of alkali] was 20.9 ml. Then in the next titration, the titre value unexpectedly fell to 10.8 ml. I mean, I would've understood if it fell to like 18 or even 17. But 11? That's a frucking huge jump, dude. The third and fourth titrations followed suit, going at 6.8 ml and 5.7 ml respectively. The last two titration attempts were laughable. 2.7 ml and 2.0 ml. It must've been a ridiculously high concentration of acid in the last titration that neutralized the alkali in such less volume.
My teacher was smiling. She said she'd let me do my titrations again some other time. I don't have much time to "try" things out as the practicals after the next one will be the part of the coursework on which I will be marked and the score will be part of my board exam score.
Ah well, at least I'm clear with the process of titration now; at least I know where I went wrong, so I'll do things the right way the next time.
After the two Chemistry periods, I had my Chemistry practicals - in my two free periods! :(
We had to neutralize 25 ml of sodium hydroxide, an alkali with some amount of oxalic acid, measure the volume of acid we used and then do some calculations to find out what how concentrated the sodium hydroxide solution we used was.
We had to prepare the oxalic acid solution, individually, from the powder and make 250 ml of acid. In the first try, I made a little bit more than needed because the friggin' glass rod was blocking the funnel that led into the flask and the water just sat there in the funnel. I realized what had happened and I removed the glass rod, and whoosh! the water went pouring into the flask, way above the 250 ml mark. Fuck. I had to prepare the oxalic acid solution all over again.
After I made exactly 250 ml of acid, I had to shake the flask well so that the water and the acid would mix and the acid solution would be equally concentrated all through the flask. I shook it a bit and said, "Ah, it must all be equal now!" and set it down. Mistake.
My first titre [volume of acid needed to neutralize the definite volume of alkali] was 20.9 ml. Then in the next titration, the titre value unexpectedly fell to 10.8 ml. I mean, I would've understood if it fell to like 18 or even 17. But 11? That's a frucking huge jump, dude. The third and fourth titrations followed suit, going at 6.8 ml and 5.7 ml respectively. The last two titration attempts were laughable. 2.7 ml and 2.0 ml. It must've been a ridiculously high concentration of acid in the last titration that neutralized the alkali in such less volume.
My teacher was smiling. She said she'd let me do my titrations again some other time. I don't have much time to "try" things out as the practicals after the next one will be the part of the coursework on which I will be marked and the score will be part of my board exam score.
Ah well, at least I'm clear with the process of titration now; at least I know where I went wrong, so I'll do things the right way the next time.