Transcript WILL IT PRECIPITATE?

WILL IT PRECIPITATE?
Background Information
Yr 10 SciB T4 EEI 2007
Introduction
 When two solutions containing dissolved ions
(i.e. ionic compounds) are mixed, the ions will
come into contact. Oppositely charged particles
attract and sometimes the attraction is strong
enough to form new compounds. Sometimes
these compounds cannot dissolve in water and
so a solid forms.
 The insoluble solid formed is called a precipitate.
Reactions in which precipitates form are called
precipitation reactions.
Yr 10 SciB T4 EEI 2007
Soluble or Not?
 All compounds containing either the Na+, NH4+, K+, or





NO3- ion will dissolve in water
Compounds containing the Cl-, Br- and I- ions are soluble
(except when they contain Ag+, Pb2+ or Hg2+ ions)
Compounds containing the SO42- ions are soluble
(except when they contain Ba2+, Pb2+ or Ca2+ ions)
Compounds containing CO32- and PO43- are insoluble
except when they contain Na+, NH4+ or K+ ions)
Compounds containing OH- are insoluble (except when
they contain Na+, NH4+, or K+ ions)
Some compounds are slightly soluble; Ca(OH)2, PbCl2,
10 SciB T4 EEI 2007
PbBr2, CaSO4 and Ag2YrSO
4
Aim:
 To observe precipitations and write
balanced equations to represent them
Yr 10 SciB T4 EEI 2007
Equipment:
 Test tubes
 White tile
 Black tile
 Safety glasses
 Solutions of; copper sulphate, potassium
iodide, calcium hydroxide, lead(11) nitrate
and sodium carbonate.
Yr 10 SciB T4 EEI 2007
Procedure
 Add 3 drops of each solution and record what colour the
resulting precipitate is (if precipitate forms)
Na2CO3
Ca(OH)2
KI
Na2CO3
Ca(OH)2
KI
CuSO4
Pb(NO3)2
Yr 10 SciB T4 EEI 2007
CuSO4
Pb(NO3)2
WILL IT PRECIPITATE?
Write-Up
Yr 10 SciB T4 EEI 2007
Hypothesis
 Predict which combinations of solutions
will produce a precipitate (submit on
separate sheet of paper to hand in next
lesson)
Yr 10 SciB T4 EEI 2007
Na2CO3
Ca(OH)2
KI
Na2CO3
Ca(OH)2
KI
CuSO4
Pb(NO3)2
Yr 10 SciB T4 EEI 2007
CuSO4
Pb(NO3)2
What’s due, When?
 Lesson 2: Hypothesis
 Lesson 3: Aim, Equipment, Procedure,
Results (prepared at home), Discussion,
Conclusion (in exam conditions during
lesson)
 9th November: Research Report
Yr 10 SciB T4 EEI 2007