Separating Techniques

Question 1

What is a solute

Answer 1

The substance which dissolves in a solution

Question 2

What is the solution

Answer 2

The name for a mixture of a solute and solvent

Question 3

What is a solvent

Answer 3

A liquid which dissolves a solute

Question 4

How would you design an experiment to see how much salt can dissolve in water, (6)

Answer 4

Measure out your given volume of water using a measuring cylinder and pour it into a beaker.

Take your given amount of salt and weigh it

Add salt, one spatula at a time and stir until it dissolves

Stop when your salt no longer dissolves

Reweigh your container of salt to see how much you’ve used.

Each group uses a different volume of water and class results are collected.

Question 5

What does “saturated” mean

Answer 5

When no more solute can dissolve in a solution

Question 6

Give the 4 states + symbols

Answer 6

(s) = solid
(g) = liquid
(g) = gas
(aq) =aqueous- dissolved in water

Question 7

What is filtration

Answer 7

The purpose of filtration is to separate an isolate solid from a solution.

Question 8

Describe the process of filtration

Answer 8

Solid is left behind on the filter paper. Liquid containing any dissolve solids pass through

Question 9

How does filtration work

Answer 9

The solid particles are too big to pass through holes in the filter paper. (Residue)

Question 10

Give an example of filtration

Answer 10

Sand from salt water

Question 11

What is the purpose of crystallisation

Answer 11

To separate a soluble solid from a solvent

Question 12

Describe the process of crystallisation

Answer 12

Take your solution, heat until crystals start to form. Then leave in a warm place for he rest of the solvent to evaporate.

Question 13

Give an example of crystallisation

Answer 13

Copper sulphate crystals from copper sulphate solution.

Question 14

Give two mixtures which can be separated from filtration

Answer 14

Iron fillings and water

Sand and water

Question 15

Give 3 mixtures which can be separated with crystallisation

Answer 15

Salt and water
Sugar and water
Copper sulphate and water

Question 16

Describe an experiment in which you can extract salt from rock salt

Answer 16

First add 5 spatulas of rock salt into a beaker and then add 20ml of water. Stir this for 3 minuets. Next, make a filter funnel by getting some filter paper and folding it in half twice. Place this in a funnel over an empty beaker. Pour the rock salt mixture into the funnel and wait until all has passed through. The liquid should still be quite blue. Pour this into an evaporating dish and place over a bunsen burner. Wear goggles and keep heating until all the water has evaporated.

Question 17

What is simple dilatation

Answer 17

Is used to separate a solvent from a solute can also be used when two miscible liquids have very different boiling points.

Question 18

What is fractional distillation

Answer 18

Is used when several miscible liquids are mixed, and have close boiling points. (Crude oil).

Question 19

How would you separate ink mixture and water

Answer 19

Heat is supplied to the flask to evaporate the water and produce steam, this steam condenses in the Liebig condenser and runs down the tube to be collected. The powder dye is left behind in the flask

Question 20

Metal oxides are called….

Answer 20

Bases

Question 21

Some bases…..in water to form soluble metal hydroxides. Soluble bases are called…..

Answer 21

Disslove

Alkalies

Question 22

…..are compounds which have replaceable hydrogen ions.

Answer 22

Acids

Question 23

……are compounds which have replaceable hydroxide ions

Answer 23

Alkalies

Question 24

Hydrochloric acid gives off salt called…….

Answer 24

Chlorides

Question 25

Sulphuric acid gives salt called......

Answer 25

Sulphates

Question 26

Nitric acid gives salts called

Answer 26

Nitrates

Question 27

Neutralisation is an......chemical reaction

Answer 27

Exothermic

Question 28

How would you make copper sulphate crystals. | 9

Answer 28

Add 20cm3 of sulphuric acid to the 100cm3 beaker.Heat carefully on the tripod on a blue flame until nearly boiling. DO NOT BOIL THE ACID! When the acid is hot, use a spatula to add a spatula of copper oxide to the beaker. Stir the mixture gently. If it all dissolves then keep adding as there is still acid to be reacted. Allow the beaker to cool slightly whilst you set up the next stage. Place the filter funnel in the neck of the clinical flask. Fold the filter paper into a funnel and put in the funnel. Gently pour the mixture in to the filter funnel. Allow to filter through. A clear blue solution should collect in the flask, If the solution is not clear and black solution still remains then repeat the filtration process. Pour this into an evaporating basin gently heat some of the water until the solution is saturated. Leave the evaporating basin in a warm place to evaporate more water. Crystals will form.

Question 29

What does chromatography separate

Answer 29

A mixture of coloured substances such as dyes.

Question 30

Why is the line drawn in paper in chromatography

Answer 30

Because with a pen, the ink would was away and be carried up the paper.

Question 31

How do you calculate the Rf value

Answer 31

Distance travelled by solute -------------------------------------------- Distance travelled by solvent

Question 32

How do you operate two immiscible liquids

Answer 32

A separating funnel is used. When the tap is open, the bottom layer runs out and can be removed while the top layer remains in the funnel.

Question 33

How would you design an experiment to do fractional distillation.

Answer 33

When heating, the mixture evaporates and goes up the column. They then meet the cool glass bead and condense back down. They the meet more hot vapour rising up which makes them evaporate agin and rise further up the column. Eventually the liquid with the lowest boiling point reaches the top and distils over.