What is necessary for a chemical reaction to reach dynamic equilibrium?

1 Answer
Aug 24, 2014

The reaction must be (a) reversible, and (b) there must be a closed system.

A chemical reaction doesn't stop when equilibrium has reached.

Instead, the rate of forward reaction equals the rate of reverse reaction.

That's why the equilibrium is dynamic. Things are still happening.

A dynamic equilibrium exists once the concentrations of reactants and products becomes constant.

Although there is no net change, substances are still moving between reactants and products at the same rate.

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The system must be closed to prevent any of the components from escaping.

Consider the equilibrium

CaCO₃(s) ⇌ CaO(s) + CO₂(g)

If the system were open, the CO₂ would escape into the atmosphere, and the equilibrium could not be established.