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Lesson No:
3 Unit Title: Solutions
      
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Unit
No: 7H
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Lesson
Title: Salt of the Earth — part I
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NC Ref:
Sc3
lh 2a
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Objectives:
MK - Water contains dissolved chemicals, dissolved solids
can be obtained by
evaporation
SK - Salt can
be
obtained from sea water or salt mines, conservation of mass
CK - Ghandi and
the
salt act.
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Lesson outline:
MK
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Discuss what happens to a muddy
puddle on a
sunny day.
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Practical —
Evaporation
with copper sulphate solution, discuss that a small amount of liquid should
be allowed to evaporate using heat from the apparatus. Too strong may change
compound (goes white).
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SS55 shows students
how to set the apparatus up for evaporation.
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Investigation —
How
much salt is in 2 samples of water. 15cm3 of
sample A, evaporate, measure the mass left. Repeat
with B. Use w/s 7HbI for lower abilities (MK,SK). 7Hb2 for higher abilities (CK).
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Plenary — MK
— Water contains dissolved chemicals and are obtained by evaporation.
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SK —
Mass
is conserved.
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Time
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Homework: none
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Resources: SS55 7Hb2 copper sulphate
solution, evaporating dishes, spatulas, glass rods, measuring
cylinders, mass balance, 1 M salt solution labelled
A, 4M salt solution labelled B.
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Risk Assessment: safety
glasses. Be aware that evaporating too
hard
will make solute spit.
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