Mistake Master
Mistake Master · AP Chemistry · Unit 9 · Step-Through Animation
It Gets Colder, and It Dissolves Anyway
You'll learnhow lattice separation and hydration combine into ΔHsolution, and why an endothermic dissolution can still be favoured.
An instant cold pack works by dissolving a salt, and it gets cold because that dissolution absorbs heat. A process that pulls heat out of its surroundings and happens anyway is not a paradox; it is the entropy term doing exactly what Topic 9.3 said it could. Twelve short steps; press Next for each one.
the lattice costs, hydration pays, and TΔS can carry the rest
Before you start
What you're looking at
A thermometer in a beaker where a salt is dissolving, and then the enthalpy ladder behind it.
The question
The beaker gets colder as the salt dissolves. So why does it dissolve at all?
Step 1 / 12