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7H Solutions
Mixtures and solutions
Separation techniques
More about solutions
7H Solutions
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7H Solutions
Mixtures and solutions
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A puresubstance contains just one type of particle.
A mixturecontains at least two different types of particle.
Its a trick question theyre all mixtures!
Do you know why?
A liquid can be pureor a mixture.
7H Mixtures and solutions - Is it pure or is it a mixture?
Which of these liquids is a mixture?
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solidno longer visible
liquidmay change colour
A solid that dissolves in water
is soluble.
solidstill visible
liquidno colour change
A solid that does not dissolve
in water is insoluble.
Does the solid dissolve?
YES NO
7H Mixtures and solutions - Does the solid dissolve?
solid + liquid mixture
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When a solid dissolves in a liquid it forms a special
type of mixture called a solution.
7H Mixtures and solutions - Whats the solution?
solvent
solvent- theliquid/substance that
does the dissolving
solvent
solvent- theliquid/substance that
does the dissolving
solute
solute- the substance being
dissolved (a solution canhave more than one solute
but only one solvent)solvent
soluteand
solution- formed when
the solvent and solute
mix togethersolution
Click on the beaker for some important solutionwords beginning with s!
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7H Solutions
Separation techniques
7H S ti t h i Filt ti
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How are tea leaves keptout of a cup of tea?
How would you separate
pasta from the cooking water?
How are coffee grains separated
from a pot of fresh coffee?
Mixtures of liquids and solids can be separated by
separation techniques.
7H Separation techniques - Filtration
Insoluble solids can be separated from a liquid by filtering.
7H S ti t h i W th lt?
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Did you know that salt is a surprisingly super-talented solid?
See if youre worth your salt by deciding if the followingstatements are true or false.
1.Salt has been used as currency. The saying being worth yoursalt comes from ancient Greece, where slaves were traded in
exchange for salt.
1.Salt has been used as currency. The saying being worth yoursalt comes from ancient Greece, where slaves were traded in
exchange for salt.
TRUE! How much salt would you be worth?
7H Separation techniques - Worth your salt?
4.Salt is found naturally dissolved in seawater. The total amountof salt dissolved in the worlds oceans would cover the area of
Britain to a depth of 3 miles!
4.Salt is found naturally dissolved in seawater. The total amountof salt dissolved in the worlds oceans would cover the area of
Britain to a depth of 3 miles!
FALSE! All the salt in the oceans would cover Britain to a
depth of 50 miles!
3.Spilling salt was considered unlucky. If you spill salt somepeople say you should throw some over your right shoulder to
cancel out the bad luck!
3.Spilling salt was considered unlucky. If you spill salt somepeople say you should throw some over your right shoulder to
cancel out the bad luck!
FALSE! Spilling salt is unlucky but you should throw the salt
over your leftshoulder.
2.Salt is found in every cell of your body. An adult human bodycontains about 70 grams of salt.
FALSE! Salt is found in every cell of your body but an adult
human contains about 250 gramsof salt!
2.Salt is found in every cell of your body. An adult human bodycontains about 70 grams of salt.
7H S ti t h i S lt t
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How could you separate the salt from a salty
seawater solution?
Its more difficult to separate the soluble solids
like salt.
You can think of the sea as a very big mixture.
What kinds of solids are found in seawater?
7H Separation techniques - Salty seawater
Its easy to separate the insoluble solids
like fish and boats.
7H S ti t h i E ti
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The liquid can be evaporated using heat from the
surroundings or by heating the solution directly.
Removing the liquid from a solution is called evaporation.
To separate dissolved solids from a solution, you need
to remove the liquid.
7H Separation techniques - Evaporation
before evaporationafter evaporation
7H Separation techniq es E aporation
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In hot countries, special ponds are flooded with
seawater and exposed to the heat of the sun.
What happens to the water?
7H Separation techniques - Evaporation
The water evaporatesand leaves the salt behind.
Salt produced in this way is called solar salt.
Why isnt solar salt produced in the UK?
7H Separation techniques Rock salt
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Rock salt can be obtained by solution mining.
Salt is also found as rock saltin layers below the
ground.
7H Separation techniques - Rock salt
7H Separation techniques Chromatography
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7H Separation techniques - Chromatography
7H Separation techniques Distillation
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How can you separate the solventfrom the solids
dissolved in a solution?
Distillation involves three stages:
The best method to separate and collect the solvent
from a solution is distillation.
boiling
condensing
collecting
7H Separation techniquesDistillation
7H Separation techniques Distillation
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Where in the distillation equipment do boiling, condensing
and collectingtake place?
7H Separation techniquesDistillation
water in
water out
boiling
thermometer
heat
heat mat
gas cools and condenses
Liebig condenser
gas turned back
to a liquid
one of liquids
in mixture
liquid
boils off
flask with
mixture
7H Separation techniques Distillation
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water in
water out
Cold water enters the outer tube at the bottom
and warm water leaves the outer tube at the top.
Why does this happen?
The most important piece of kit for distillation is the
Liebig condenser.
7H Separation techniquesDistillation
2.Cold water in the outer tube cools the hot
gas, which condenses to become a liquid.
3. The liquid is collected at the bottom.
1. Hot gas
passes down
the inner
tube.
7H Separation techniques Summary
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2. Do you want to collect the solid(solute)
or the liquid(solvent) from the solution?
1. Is the solid solubleor insoluble?
7H Separation techniques - Summary
The choice of separation technique depends on
two things:
7H Separation techniques - Summary
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Match the correct description to the separation technique.
Name
1 Evaporation
2 Filtration
3 Chromatography
4 Distillation
DescriptionAis used to separate small amounts of
two or more solids which are soluble
in the same solvent.
Bis used to separate a soluble solidfrom the liquid to obtain the solute.
Cis used to separate a soluble solid
and a liquid to obtain the solvent.
Dis used to separate an insoluble solid
from a liquid.
7H Separation techniques - Summary
7H Solutions
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7H Solutions
More about solutions
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7H More about solutions - Conservation of mass
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7H More about solutions Conservation of mass
A spoonful of sugar is added to a beaker of water.
The water and the sugar solution are the same colour.
Why do they have different masses?
Mass of water = 50g Mass of spoonful
of sugar = 7g
Mass of sugar
solution = 57g
+
7H More about solutions - Particles in a solution
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7H More about solutions Particles in a solution
What happens to the particles?
A solid does not disappear when it dissolves to form a
solution.
In a solution, the particles from the solute are no
longer closely packed together. They are evenly
spread out between the particles of the solvent.
Why is dissolvingis not the same as melting?
solute + solvent solution
7H More about solutions- Saturated solutions and solubility
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7H More about solutions Saturated solutions and solubility
When a solid dissolves in a liquid to make a solution,
eventually no more solid will dissolve.
The solution is saturated.
How much sugar can you dissolve in a cup of tea?
If you keep adding sugar to a cup of tea you end up
with a very sweet drink and a gloopy mess!
7H More about solutions - Solubility and temperature
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7H More about solutions Solubility and temperature
The total amount of a solid that can dissolve in a
solution is called the solubility.
What happens to the solubility of sugar as the
temperature increases?
Temperature Solubility of sugar
(OC ) per 100g of water
0 179.210 190.5
20 203.9
30 219.5
40 238.1
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