How is equilibrium represented in chemical equations?

Equilibrium in chemical equations is represented by a double-headed arrow (↔).

In a chemical equation, equilibrium is denoted by a double-headed arrow, pointing in both directions. This symbol signifies that the forward and reverse reactions are happening at the same rate. It's important to note that this doesn't mean the amounts of reactants and products are equal, but rather that their concentrations remain constant over time.

For example, consider the reversible reaction of nitrogen and hydrogen to form ammonia:

N2(g) + 3H2(g) ↔ 2NH3(g)

The double-headed arrow in this equation indicates that the reaction can proceed in both directions. On the left side of the arrow, nitrogen and hydrogen are reacting to form ammonia. This is the forward reaction. On the right side of the arrow, ammonia is decomposing back into nitrogen and hydrogen. This is the reverse reaction.

When the rate of the forward reaction equals the rate of the reverse reaction, the system is said to be in a state of dynamic equilibrium. At this point, the concentrations of the reactants and products remain constant, even though the reactions are still occurring. This is a key concept in understanding how chemical reactions work.

In summary, the double-headed arrow in a chemical equation is a visual representation of equilibrium. It signifies that the forward and reverse reactions are happening simultaneously and at the same rate, leading to constant concentrations of reactants and products. This is a fundamental concept in IGCSE Chemistry and is crucial for understanding how chemical reactions occur.