Chemical Analysis

Question 1

what is a mixture

Answer 1

consists of two or more different substances, not chemically joined together

Question 2

what is a pure substance

Answer 2

a single element or compound, not mixed with any other substance

Question 3

what is a melting point

Answer 3

is the temperature at which a solid changes into a liquid

Question 4

what is a boiling point

Answer 4

the temperature at which a liquid changes into a gas

Question 5

melting point of water

Answer 5

100 degrees

Question 6

what is distilled water

Answer 6

water as a pure substance without any other impurities as it exists as a single compound, not mixed with any other substance.

Question 7

What is a formulation

Answer 7

A mixture that has been designed as a useful product. They are made by mixing the components in carefully measured quantities to ensure that the product has the required properties.

Question 8

Name 7 examples of formulations

Answer 8

Fuels, cleaning agents, paints, medicines, alloys, fertilisers, foods.

Question 9

how is a formulation made

Answer 9

by mixing the components in carefully measured quantities to ensure that the product has the required properties.

Question 10

what is chromatography

Answer 10

the name given to the process of separating dyes and inks

Question 11

The more soluble a dye is in its solvent, will it travel less or more

Answer 11

travel more, further

Question 12

A pure substance produces a single or multiple spot in solvents

Answer 12

single

Question 13

a compound in a mixture will separate into diff dyes depending on solvent or create a single dot

Answer 13

separate into different dyes

Question 14

What is the mobile phase

Answer 14

the phase that is moving

Question 15

give an example of a mobile phase

Answer 15

water (its moves up thro the paper)

Question 16

what is a stationary phase

Answer 16

is the not moving part

Question 17

give an example of a stationary phase

Answer 17

(chromatography) paper

Question 18

what does affinity mean

Answer 18

attraction

Question 19

if a sample has a greater affinity to the mobile phase, will it travel further or stop sooner

Answer 19

further

Question 20

if a sample has a greater affinity to the stationary phase, will it travel further or stop sooner

Answer 20

stop sooner

Question 21

Rf formula

Answer 21

distance moved by chemical / distance moved by solvent

Question 22

the bigger the rf value the what?

Answer 22

the further the spot moved

Question 23

why does paper chromatography work

Answer 23

because each chemical in the mixture will be attracted to the stationary phase to a different extent, ie strongle attracted chemicals won’t travel far whereas weakly attracted chemicals will travle further

Question 24

why do we draw a line in pencil for paper chromatography

Answer 24

because if we drew it in pen ink, the ink would move uo the paper with the solvent

Question 25

explain how paper chromatography separates substances

Answer 25

mobile phase / solvent moves thro paper and carries substances diff distances whichdepend on their affinity for paper and solvent

Question 26

what is solvent front

Answer 26

the furthest poibt reached by the solvent in chromatography

Question 27

how can we use paper chromatography to analyse a colourless substance

Answer 27

we can use a locating agent to react these with substances to form coloured products, or products that glow under ultraviolet light

Question 28

what is solvent level

Answer 28

place where the chosen solvent is placed

Question 29

what is the baseline

Answer 29

place where the samples of the substances are placed

Question 30

uses of chromatography

Answer 30

to separate mixtures of coloured compounds, identify pure and impure substances, for drug testing

Question 31

how can chromatography be used to identify unknown dyes in food colouring

Answer 31

run a known dye and food coloruing (9for comparing) compare the distances moved / rf value if they move the same distance/ have same rf value, they must be the same substances

Question 32

what is a solvent

Answer 32

a liquid that dissolves substances

Question 33

what is a solute?

Answer 33

a substance that can be dissolved by a solvent to create a solution