Cat3 IA Chem Nov 2025

Paid the IB tax for another 5 years. Learnt nothing.

Acid - Carbonate at a reasonable rate

Marble chips - two small chips for a total of 1g

Hydrochloric acid - 20ml of 1 M

50 ml of carbon dioxide will be released in about 3 or 4 minutes at 293 K

Chemistry Cat. 3 IA Certificate

March 2016. Online intro to IA for those who already know. Not much insight into the new mode where students have to think of their own personal experiment.

24h acid hydrolysis

Needing to hydrolyse some protein foods down to amino acids by boiling for 24h in 6M HCl, I came up with a new "invention".

Place four 100ml conical flasks full of water into a 2l Japanese water boiler, about half-full, so as not to cause the flasks to float. Having four of them means they can't tip over anyway.

Then place your hydrolysis solution in a boiling tube into one of the flasks (or do up to four at once). I stoppered it with a one-hole stopper, to prevent too much water dripping into the tube and diluting the HCl or causing it to overflow.

I set the boiler to 90^oC, not 98, to reduce the amount of bumping.

It works really well, and is so much safer than using a normal water bath.

Thiosulphate - Acid in a reasonable time

Struggling to get a simple thiosulphate - hydrochloric rate of reaction practical to work in a handful of minutes, trial and error brings me to this conculsion

0.1M sodium thiosulphate  + 1.0M hydrochloric acid + water in equal volumes gives about 6 minutes to obscure a cross at 20^oC, or about 2 minutes to max out a turbidity sensor at the same temp.