Water HardnessReview its causes
Identify cations causing hardnessClassify differnet types of harness
Observe its effects – harmful and beneficialUnderstand procedures to remove water hardness
Title: Hard and Soft WaterObjectives• – describe key features of hard and soft water. • - explain how to identify hard and soft waters
Starter – What has happened to these kettles and this bathroom?
SOAP
SCUM
PermanentHardwaterMinerals (Salts)
Water hardness in the UK by regionWhere will your kettle last the longest?
YorkshireCheshire
Peak DistrictMalvern
SomersetCornwall Guildford
LO – to describe key features of hard and soft water. - To explain how to identify hard and soft waters
Temporary Hard water = Ca(HCO3)2 or Mg(HCO3)2
SOAP
SCUM
Does furring in kettles occur in all types of water? B – what is needed for this reaction?
Calcium calcium + carbon carbonate oxide dioxide
Install a water softener
Na+
Ca2+
Mg2+
Na2CO3
Sodium CarbonateCalcium ions + Sodium Carbonate
Sodium ions + Calcium Carbonate
The Water CycleQ - Where in this water cycle does our drinking water come from?
Hard water contains dissolved compounds, usually of calcium or magnesium. The compounds are dissolved when
acidic water comes into contact with rocks.
The Water Cycle and water hardness – the chemistry
Hard water contains dissolved compounds, usually of calcium or magnesium. The compounds are dissolved when slightly acidic water comes into
contact with rocks.
CaCO3(s) + H2O(l) + CO2(aq) Ca2+(aq) 2HCO3-(aq)
Titel: Temporary and Permanent Hard WaterLernziel• to be able to distinguish between temporary hard water and permanent
hard water• To be able to explain what happens when we heat temporary hard water
Starter A – Does furring in kettles occur in all types of water?
B – what is needed for this reaction?
Calcium calcium + carbon carbonate oxide dioxide
Temporary hard water chemistry
this is caused by the presence of CaHCO3 compound – soluble in water
LO – to be able to distinguish between temporary hard water and permanent hard water- To be able to explain what happens when we heat temporary hard water
Ca2+(aq) 2HCO3-(aq) CaCO3(s) + H2O(l) + CO2(g)
heat
(scale)(‘hardness’)
Permanent hardness is caused by the presence of soluble Ca2+ and Mg2+ ions in water
Review – explaining how temporary hard water is softened by boiling
Choice 1Explain which ions are missing from soft water
Choice 2Explain the symbol equation for the reaction of calcium ions with carbonate to form scale in full sentences.
Choice 3Write a balanced symbol equation for the reaction of Magnesium ions with carbonate ions to form scale
CompulsoryWrite definitions for these key wordsPermanent hard water temporary hard water
LO – to be able to distinguish between temporary hard water and permanent hard water- To be able to explain what happens when we heat temporary hard water