Chemical analysis

Question 1

What is a pure substance?

Answer 1

It is 1 type of element or compound.

Melt and boil at one temp

Question 2

What is a formulation and give an example?

Answer 2

mixtures that have been carefully designed to have specific properties
EG cleaning agents, paints ,medicine
Many formulations have complex mixtures in which each chemical has its own purpose

Question 3

What is chromatography?

Answer 3

separates mixtures into their constituent component
The solvent dissolves and carries them up the paper
can be used to identify artificial colours

Question 4

What is the gas test for hydrogen and oxygen?

Answer 4

HYDROGEN-mixed with air burns with a squeaky pop

OXYGEN-relights a glowing splint

Question 5

What is the procedure for the instrumental method?

Answer 5

1) A sample of metal solution is placed in a flame and the light emitted is passed through a spectroscope
2) Producing a line through spectrum which can be used to identify metal ions in the solution and measure the conc of the metal ions in the solutions

Question 6

What is an impure substance?

Answer 6

It is a mixture.

They do not boil and melt at one temp they change state over a range of temp

Question 7

What is the Rf equation?

Answer 7

Rf= distance moved by substance/distance by solvent

Question 8

What is the difference between station phase and mobile phase?

Answer 8

Stationary phase is when it does not move mobile phase is when it moves

Question 9

What colour does indicator paper turn in the chlorine test/What solution is produced in the carbon dioxide gas test?

Answer 9

CHLORINE-turns damp indicator paper white

CARBON DIOXIDE-when bubbled through lime water a solution of calcium hydroxide turns the lime water cloudy

Question 10

What is the instrumental method?

Answer 10

Flame emission spectroscopy is used to analyse solutions that contain metal ions

Question 11

What alloy do you but in the Bunsen burner flame/what acid is used in this experiment?

Answer 11

Piece of nichrome wire in a Bunsen flame and then dip it in concentrated hydrochloric acid to clean it

Question 12

What do you do after dipping it in the hydrochloric acid?

Answer 12

Dip the wire in a compound and put it in the flame to see what colour it produces

Question 13

What colour shows copper & calcium ion is present/If the colour crimson red is shown which ion is present

Answer 13

GREEN-CU
BRICK RED-CA
lithium-crimson red

Question 14

If the colour lilac and yellow is shown what ions are present?

Answer 14

lilac-potassium

yellow-sodium

Question 15

What do carbonates react with/what do they produce give example?

Answer 15

React with dilute acid to form carbon dioxide

Calcium carbonate + hydrochloric acid— calcium chloride + carbon dioxide + water

Question 16

What does carbon dioxide to do lime water/Are most metal carbonates soluble or insoluble?

Answer 16

Turn lime water cloudy (milky)

insoluble

Question 17

What three metals forms a white precipitate when mixed with sodium hydroxide solution?

Answer 17

Aluminium-dissolves if more sodium hydroxide solution is added
CA,MG does not dissolve in excess sodium hydroxide
calcium
magnesium

Question 18

When copper reacts with sodium hydroxide what precipitate is formed?

Answer 18

dark Blue

Question 19

What is the difference between iron (11) and iron (111) when mixed with sodium hydroxide solution?

Answer 19

iron 11 forms green precipitate

iron 111 forms brown precipitate

Question 20

What do you need for a white precipitate of barium sulfate to be produced?

Answer 20

dilute hydrochloric acid + barium chloride solution and a solution that contains sulfate ions

Question 21

What do halide ions react with?

Answer 21

silver nitrate solution and dilute nitric acid to form silver halide precipitate

Question 22

What colour precipitation does silver chloride, bromide and iodide produce?

Answer 22

chloride-white
bromide-cream
iodide-yellow