P2 - Chemical Analysis

Question 1

Define a pure substance

Answer 1

Something that contains one compound or element - not mixed with anything else

Question 2

What are the two phases of chromatography?

Answer 2

Mobile - where the molecules can move (solvent)

Stationary - where the molecules can’t move (chromatography paper)

Question 3

How do you calculate the Rf value?

Answer 3

Distance travelled by substance
———————————
Distance travelled by solvent

Question 4

What is the test for chlorine?

Answer 4

Bleached damp litmus paper

Question 5

What is the test for oxygen?

Answer 5

Relights a glowing splint

Question 6

What is the test for carbon dioxide?

Answer 6

Turns limewater cloudy

Question 7

What is the test for hydrogen?

Answer 7

Burns with a squeaky pop

Question 8

What is the test for carbonates?

Answer 8

Add dilute acid to it in a test tube then connect with test tube of limewater to see if carbon dioxide is present

Question 9

What is the test for sulfates?

Answer 9

Add dilute HCl and then barium chloride solution to it and white precipitate forms.

Question 10

What is the test for halides?

Answer 10

Add dilute nitric acid and silver nitrate solution and a white/cream/yellow precipitate will form depending on which halide it is.

Question 11

What are the colours of the flame tests?

Lithium, sodium, potassium, calcium, copper

Answer 11

Lithium - red
Sodium - yellow
Potassium - purple
Calcium - Orange-red
Copper - green

Question 12

What colour precipitates do metal hydroxides form when sodium hydroxide is added to them?

Calcium, copper, Iron(II), Iron(III), Aluminium, Magnesium

Answer 12

Calcium - white
Copper - blue
Iron(II) - green
Iron(III) - Brown
Aluminium - white then colourless
Magnesium - white