A pale red solution holds Fe³⁺(aq) + SCN⁻(aq) ⇌ [Fe(SCN)]²⁺(aq), where the product is blood red…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A pale red solution holds , where the product is blood red. Predict the colour change when you add (a) a few crystals of potassium thiocyanate, KSCN; (b) oxalic acid, which takes out of the solution; (c) water.
Need a reminder? The key ideaShow
Le Chatelier: a disturbed equilibrium shifts to undo part of the change. Adding a reactant or removing a product shifts it forward. Higher pressure favours fewer moles of gas. Heating favours the endothermic direction and changes K. A catalyst does not shift the equilibrium.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. KSCN. More shifts the equilibrium forward. The red deepens.
Step 2. Oxalic acid. Removing shifts it backward. The red fades.
Step 3. Water. Every concentration falls, and the mixture shifts towards the side with more particles, the reactants. The colour pales, more than by dilution alone.
Answer: deeper red, paler, paler.
Discussion (0)
Log in to join the discussion.
Loading…