Water - Solubility - Ions
Hardness of Water.
is said to be hard if it doesn't form a lather
with soap. Calcium and magnesium ions cause water to be hard.
Hardness is described as "permanent" or "temporary".
water is naturally acidic due to dissolved
(see the Carbon Cycle).
The acid in rain water is carbonic acid, H2CO3(aq).
containing magnesium carbonate or
calcium carbonate (limestone), will react
with dilute carbonic acid forming hydrogencarbonates.
acid + calcium
carbonate calcium hydrogencarbonate.
H2CO3(aq) + CaCO3(s) Ca(HCO3)2(aq)
acid + magnesium
carbonate magnesium hydrogencarbonate.
H2CO3(aq) + MgCO3(s) Mg(HCO3)2(aq)
These hydrogencarbonates are
slightly soluble in water, causing hardness.
Links Water Revision Questions
gcsescience.com The Periodic Table Index Water Quiz gcsescience.com
Home GCSE Chemistry GCSE Physics
Copyright © 2014 Dr. Colin France. All Rights Reserved.