I know many of you will share my feelings of indescribable goodness when an experiment turns out super-well. Let me share . . .
We just finished a quantitative electrolysis of dilute sulfuric acid. One of the objectives was to determine a value for the Faraday constant and for the Avogadro constant. In our post-lab discussion, I randomly asked a pair of students for their “numbers”, which we worked through as a group. (I ask students not to copy the calculations that I write on the board — this would make their calculations too easy, too algorithmic.) Long story short: To two significant figures, they nailed it!
Joy of Joys!
Let me put it this way: We determined empirically the
SI unit for quantity of matter — and we determined it with great accuracy in Grade 12 — Grade 12!!! Not in an Ivy League university research lab or in some geeky rogue-professor’s basement at his mother’s house.
In grade 11 chemistry, we treat a (weighed) piece of Mg with excess HCl(aq) and collect the hydrogen gas in a 250 mL Erlenmeyer flask by downward displacement of water. Students mark the level of H2(g) collected using a grease pencil and determine its volume using a graduated cylinder and water. (We don’t correct for anything.) For sure, this method lacks precision, but the results! Molar volume of H2: 25 L at ca SATP!!! To satisfy the cynics, I demonstrate the reaction of bleach, NaOCl(aq), with aqueous H2O2 to obtain the same value for O2(g).
Joy of joys!
Titration-wise, we determine the molar mass of citric acid, oxalic acid, potassium hydrogen phthalate by acid-base titration. Results, you ask? Muchas accurate.
Joy of joys!
We determine the molar mass of CO2 (using dry ice) and CH4 (from our natural gas taps) using a 2-L soda bottle, to exquisite accuracy.
Joy of joys!
I could go on . . .
We are chemists, everyone! And we do good work in the lab — useful work, accurate work.1
Note
1. And we are nice and people like us and we smell good
