7H Solutions

8/13/2019 7H Solutions

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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?



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



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



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



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



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



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Where in the distillation equipment do boiling, condensing

and collectingtake place?


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



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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.


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:



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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 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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