chemical analysis, assessing purity and separating mixtures, flame tests

Question 1

what is the smallest particle of an element

Answer 1

an atom

Question 2

what is a molecule

Answer 2

it is a particle that consists of 2 or more atoms that are chemically combined

Question 3

what is an element

Answer 3

it is a substance that consists of only 1 type of atom that cannot be easily separated

Question 4

what is a compound

Answer 4

It is a substance that consists of two or more elements that are chemically combined

Question 5

what is a mixture

Answer 5

it is where 2 or more substances are mixed but not chemically combined. there are no chemical bonds between them

Question 6

properties of mixtures

Answer 6

A mixtures components are easily separated because they are not chemically joined together

Question 7

properties of compounds

Answer 7

the components of a compound do not retain their individual properties. both sodium and chloride are poisonous; their compound, table salt (sodium chloride) is absolutely essential to life

it takes large inputs of energy to separate the components of a compound because they are chemically combined

Question 8

what is a pure substance

Answer 8

it is a single element or compound not mixed with any other substances

Question 9

what is the melting point

Answer 9

it is the temperature at which a solid changes into a liquid

Question 10

what is the boiling point

Answer 10

it is the temperature at which a solid changed into a liquid

Question 11

what is a formulation

Answer 11

it is a mixture which has been designed as a useful product and is formed by mixing together several different substances in carefully measured quantities to ensure the product has the required properties

Question 12

what is a soluble substance

Answer 12

it is substance is one which dissolves in water

Question 13

what is a insoluble substance

Answer 13

it is substance is one which doesn’t dissolves in water

Question 14

what is a solute

Answer 14

it is a soluble substance which dissolves in water

Question 15

what is a solvent

Answer 15

it is the liquid which a solute dissolves in

Question 16

what is a solutions

Answer 16

it is formed when a solute dissolves in a solvent

Question 17

what is the residue

Answer 17

it is the solid which remains on the filter paper

Question 18

what is filtrate

Answer 18

it is the solution which passes through the filter paper

Question 19

what is distillate

Answer 19

it is the liquid which is collected by condensation of a vapor during the distillation process

Question 20

what is miscible

Answer 20

liquid mix

Question 21

what is immiscible

Answer 21

liquid doesn’t mix

Question 22

what is evaporation

Answer 22

occurs when a liquid changes to a gas below the boiling point

Question 23

what is condensation

Answer 23

occurs when a gas changes to a liquid

Question 24

what is the RF mean

Answer 24

distance moved by spot distance moved by solvent

Question 25

what is anhydrous copper (ll) sulfate

Answer 25

it is a white solid which doesn’t contain any water of crystallisation if added to water it will turn from white to blue and if it was heated with the water it will turn from blue back to white

Question 26

explain filtration

Answer 26

This method works by pouring a mixture of an insoluble solid and a liquid (which could itself be a solution through filter paper in a filter funnel. The solid, called the residue, is caught in the filter paper. The liquid called the filtrate, passes through the filter paper and is collected as it drips out of the spout of the funnel.

Question 27

explain evaporation and crystallisation

Answer 27

This method works by boiling off a liquid from a solution which contains a solid (called a solute) dissolved in a liquid (called a solvent) which is often water. This is done in an evaporating basin to leave a solid (called the residue). Better crystals can be obtained by heating the solution gently until only half of its original volume remains. The concentrated solution is then allowed to cool and crystallise. If some solution remains, then further filtration can be used to obtain the crystals of solute which then be dried between two sheets of filter paper.

Question 28

explain simple distillation

Answer 28

This method is used to obtain a solvent from a solution. The liquid is boiled off in a flask and then its vapour is cooled by using a Liebig condenser so that it condenses back to a liquid. The collected liquid is called the distillate, Simple distillation can also be used to separate two miscible liquids whose boiling points are far apart.

Question 29

explain fractional distillation

Answer 29

This method works by separating a mixture of two or more miscible liquids whose boiling points are quite close together. It is similar to simple distillation except that a special tube called a fractionating column is placed between the flask and the condenser. As the liquid is heated, the liquid with the lowest boiling point boils off first. This is then condensed and collected as a pure liquid. After the first liquid has been collected the second liquid may be distilled over and so on. The different distillates are known as fractions.

Question 30

explain separating funnel

Answer 30

If two Liquids do not mix, they are said to be immiscible eg oil and water. The separation of two immiscible liquids is very simple. The mixture is placed in a separating funnel where the less dense liquid will form the upper layer. The two liquids can then be run out of the funnel one after the other.

Question 31

explain chromatography

Answer 31

Paper chromatography is the simplest type of chromatography. It works by separating a mixture of different soluble substances (usually with different colours). A spot of the mixture is placed on some chromatography paper (stationary phase) which is then dipped into a solvent (mobile phase). As the solvent passes up the paper, the mixture separates aut as different spots as each substance in the mixture moves at a different rate up the paper. The components separate because some are more attracted to the paper whilst others are more attracted to the solvent. Those that prefer to dissolve in the solvent move faster and travel further up the paper.

Question 32

what colour flame is Potassium K+

Answer 32

lilac

Question 33

what colour flame is Calcium Ca2+

Answer 33

brick red

Question 34

what colour flame is Copper(ll) Cu2+

Answer 34

blue-green

Question 35

what colour flame is Sodium Na+

Answer 35

pick one between yellow or orange

Question 36

what colour flame is Lithium Li+

Answer 36

crimson