Mixtures

Question 1

What is sieving?

Answer 1

-method to separate two solids of different sizes

Question 2

Chromatography: The more soluble a substance is….

Answer 2

….the further up the paper it will travel

Question 3

What does chromatography separate?

Answer 3

-different colours with different solubilities

Question 4

What is a solute?

Answer 4

-substance that dissolves in a solvent

Question 5

What is a solvent?

Answer 5

-liquid that a solute dissolves in

Question 6

What is a solution?

Answer 6

-solute dissolved in a solvent

Question 7

What does soluble mean?

Answer 7

-when a substance will dissolve in a solvent

Question 8

What does insoluble mean?

Answer 8

-when a substance will not dissolve in a solvent

Question 9

What does miscible mean?

Answer 9

-to describe liquids that mix together

Question 10

What does immiscible mean?

Answer 10

-to describe liquids that do not mix together

Question 11

What is residue?

Answer 11

-solid left over on filter paper after filtration

Question 12

What is saturated (in terms of solutions)?

Answer 12

-solution in which no more solute can dissolve at that temperature

Question 13

What is filtration used for and how does it work?

Answer 13

-separate insoluble solid from its solvent
-mixture is poured through funnel containing filter paper
-solvent passes through the filter paper but solid remains on it

Question 14

What is a filtrate?

Answer 14

-liquid that passes through the paper during filtration

Question 15

What is evaporation used for and how does it work?

Answer 15

-to separate a soluble solid from its solvent
-solution is poured in evaporating dish and heated
-solvent will evaporate/boil leaving solid in the dish

Question 16

What is crystallisation used for and how does it work?

Answer 16

-to separate a soluble solid from its solvent

-mixture is heated to boil off the solvent and create a hot saturated solution

-as it cools down, the solute becomes less soluble and is crystallised

-crystals can then be separated with filtration

Question 17

What is simple distillation used for and how does it work?

Answer 17

-used to separate the solvent from a solution
-mixture is heated and the solvent boils
-vaporised solvent then travels down a water-cooled condenser and condenses back into a liquid into a separate beaker

Question 18

What is fractional distillation used for and how does it work?

Answer 18

-used to separate 2 or more miscible liquids
-whole mixture is vaporised
-then condensed in a fractionated column that is cold at the top and hot at the bottom
-liquids are separated as they have different boiling points

Question 19

What is chromatography used for and how does it work?

Answer 19

-used to separate mixtures of soluble substances dissolved in a solvent
-chromatography paper , with the mixture on, is lowered in the solvent
-solvent soaks up the paper and substances move up it at different speeds, so re separated

Question 20

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Answer 20

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Question 21

What is the difference between a mixture and compound in terms of proportions?

Answer 21

-compound has a fixed proportion of elements (fixed formula)
-mixture can have any amount of a substance

Question 22

What is the difference between a mixture and a compound in terms of separation?

Answer 22

-mixture can be separated physically with separation methods, as substances aren’t chemically joined
-all the elements in a compound are chemically joined so they are separated back into elements with chemically reactions

Question 23

What is a compound?

Answer 23

-made from 2+ elements bonded together
-has its own unique properties

Question 24

What is a mixture?

Answer 24

-made of two or more substances (with their own properties) that aren’t chemically joined

Question 25

Why do we separate substances?

Answer 25

-to make pure substances

Question 26

What new substances are made during physical separation?

Answer 26

-none

Question 27

What is the best definition of a pure substance?

Answer 27

-substance that consists of only one element or compound

Question 28

In chromatography, what is the mobile phase?

Answer 28

-the solvent that moves through the paper

Question 29

What is an element?

Answer 29

-substance made up of one type of element

Question 30

Why do compounds have different properties from the elements that they are made of?

Answer 30

-elements are chemically joined, so instead of having many separate properties of different elements, the elements combine to give the compound its own unique properties