This topic accounts for approximately 6% of your exam marks.
stable
Low
Stable6%
Haber process conditions and Le Chatelier's principle regularly examined.
What "reversible" means
A can proceed in both directions: the products can themselves combine, or break apart, to give the original reactants back again
The turns reactants into products
The reverse (backward) reaction turns products back into reactants
A reversible equation uses a special two-headed arrow, ⇌, instead of the single arrow → used for one-way reactions
The top half-arrow points right (forward); the bottom half-arrow points left (reverse)
Whether the reaction settles toward the products side or toward the reactants side depends on the conditions — temperature, pressure, concentration
Two reversible reactions to know
Heating hydrated copper(II) sulfate drives off its water of crystallisation: the blue crystals turn white as CuSO4·5H2O becomes anhydrous CuSO4. Adding water reverses the change, turning the white solid blue again and releasing heat, which is why anhydrous copper(II) sulfate is used as a test for water: CuSO4·5H2O ⇌ CuSO4 + 5H2O
Heating ammonium chloride decomposes the white solid into ammonia and hydrogen chloride gas; the two gases recombine on the cooler upper walls of the tube to reform solid ammonium chloride: NH4Cl ⇌ NH3 + HCl