Illustrate Le Chatelier’s Principle by demonstrating the effects of concentration changes

Draw a diagram of this experiment

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Step 1

Add a drop of potassium thiocyanate solution to iron (III) chloride

What is observed?

Red colour is observed

Explain observation

Equilibrium shifts to RHS

Equation of experiment

Fe³⁺ + CNS^- ⇌ Fe(CNS)²⁺

Step 4

Add dilute hydrochloric acid until a colour change is observed

What is observed when hydrochloric acid is added?

Red colour disappears

Draw a diagram showing the experiment when hydrochloric acid is added

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Explain the observation when hydrochloric acid is added

Equilibrium favours left side as LHS reacts with Cl^- ions to produce the reactants

Step 7

Add in some potassium thiocyanate solution

What do you observe when potassium thiocyanate ions are added?

Solution turns red

Explain the observation when potassium thiocyanate is added

Equilibrium shifts to RHS absorbing CNS^-

Draw a diagram of the solution when potassium thiocyanate is added

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