gcsescience.com 19 gcsescience.com
Water - Solubility - Ions
Negative Ions - Carbonate.
Any carbonate will produce carbon dioxide gas
when you add a dilute acid.
For example, adding hydrochloric acid to sodium carbonate solution
HCl + sodium carbonate
sodium chloride + carbon
dioxide + water.
2HCl(aq) + Na2CO3(aq) 2NaCl(aq) + CO2(g) + H2O(l)
dioxide gas is identified with the usual
(see other examples).
Some carbonates change colour during thermal decomposition.
oxide + carbon dioxide
CuCO3(s) CuO(s) + CO2(g)
Copper carbonate is green and becomes copper oxide which is black.
zinc carbonate zinc oxide + carbon dioxide
ZnCO3(s) ZnO(s) + CO2(g)
carbonate is white and
becomes yellow zinc oxide.
Zinc oxide is yellow when it is hot
but becomes white again when it cools down.
Links Water Revision Questions
gcsescience.com The Periodic Table Index Water Quiz gcsescience.com
Home GCSE Chemistry GCSE Physics
Copyright © 2015 gcsescience.com. All Rights Reserved.