A gardener finds that the soil in one of her vegetable patches is too acidic.
Acidic soil can be neutralised by spreading calcium hydroxide, Ca(OH)2\text{Ca(OH)}_2Ca(OH)2, onto the soil. The gardener uses 18.0 kg18.0\text{ kg}18.0 kg of calcium hydroxide.
Calculate the number of moles of calcium hydroxide the gardener uses. (Ar:Ca=40.1;O=16.0;H=1.0)(A_r: \text{Ca} = 40.1; \text{O} = 16.0; \text{H} = 1.0)(Ar:Ca=40.1;O=16.0;H=1.0)
Give your answer to 3 significant figures.