UTC: Thursday, February 21st, 2019

Le Châtelier’s principle in action

Following the mention of the cobalt(II) complex ion system in this post from a couple of days ago, here’s a 30 second video clip of Le Châtelier’s principle in action in the same (with The Smiths). The equilibrium that is set up is this, [Co(H2O)6]2+(aq) + 4Cl–(aq) ⇌ [CoCl4]2-(aq) + 6H2O(l) and the aqueous solution […]

‘Expanded LCP’ or ‘Q versus K’ explanations?

It’s never been OK, on the AP exam, to offer a simple, ‘because of Le Châtelier’s principle‘ argument as the explanation for the shift of an equilibrium position caused by an external stress. This is in much the same way that it has never been acceptable to say, ‘because as you go across the period first […]

Inert gases and gaseous equilibrium mixtures

What happens when an inert gas is added to a gaseous equilibrium mixture at constant volume? Before we answer that question, it might be worth defining what we mean by “an inert gas”. In this context we mean a gas that is not involved in the equilibrium reaction, or one that reacts with any of […]

The mess that is ‘signs’ and q = m c ∆T

This is messy – really messy – and don’t even get me started on work, internal energy and all that nonsense (which is a catastrophic minefield of bizarre ‘conventions’), but I thought it was time to crystallize a few thoughts on this. As usual, when studying Thermodynamics with my AP classes, I did a lab […]