Chemical Analysis

Question 1

What are the melting points like in pure substances

Answer 1

Narrow. High melting and low boiling

Question 2

What are the melting and boiling pints like it impure substances

Answer 2

Wide range. Higher boiling points and lower melting points

Question 3

What is a formulation

Answer 3

A mixture that’s has been designed as a useful chemical product in which each chemical has a particular purpose

Question 4

How do you test for hydrogen

Answer 4

Use a lit spilt held at the open end at the test tube. There will be a popping sound

Question 5

How do you test for oxygen

Answer 5

Use a glowing splint. It will relight

Question 6

How do you test for Carbon dioxide

Answer 6

Use limewater (calcium hydroxide). The limewater will turn milky (cloudy)

Question 7

How to test for chlorine

Answer 7

Use litmus paper. It will turn white

Question 8

Why is chromatography used

Answer 8

To identify unknown substances as the compounds will separate

Question 9

In chromatography what is it meant by low value

Answer 9

Not very soluble

Question 10

In chromatography what is it meant by high value

Answer 10

Very soluble

Question 11

In chromatography what is it meant by mobile

Answer 11

The parts that travel such as the solvent

Question 12

In chromatography what is it meant by stationary

Answer 12

The parts that don’t move such as the paper

Question 13

How do you calculate the retention factor

Answer 13

Distance the spot moved/distance solvent moved

Question 14

What things must you remember to do when setting up chromatography

Answer 14

Keep the solvent under the base line

Draw the base line in pencil

Question 15

What is the precipitate for aluminium

Answer 15

White

Question 16

What is the precipitate for calcium

Answer 16

White

Question 17

What is the precipitate for magnesium

Answer 17

White

Question 18

What is the precipitate for copper (III)

Answer 18

Blue

Question 19

What is the precipitate for iron (II)

Answer 19

Green

Question 20

What is the precipitate for iron (III)

Answer 20

Brown

Question 21

In a flame test what colour is lithium

Answer 21

Crimson (red)

Question 22

In a flame test what colour is sodium

Answer 22

Yellow

Question 23

In a flame test what colour is potassium

Answer 23

Lilac

Question 24

In a flame test what colour is calcium

Answer 24

Orange-red

Question 25

In a flame test what colour is copper

Answer 25

Green

Question 26

What is the method for flame test for cations

Answer 26

Wore loop dipped in hydrochloric acid. Placed in flame. Placed in acid. Dip in metal being tested. Hold in the blue flame.

Question 27

What is the metal action test

Answer 27

Add sodium hydroxide to metal cation solution. Note colour

Question 28

What is a potential problem with flame tests

Answer 28

Some of the elements are the smae colour so the result is not a definite answer

Question 29

How do you test for carbonates

Answer 29

Add dilute acid to the carbonate. If it fizzes and produces carbon dioxide collect it. Test for unknown substances. Carbon dioxide will turn it cloudy

Question 30

How do you test for sulfates

Answer 30

Add dilute hydrochloric acid. Add barium chloride. White precipitate if sulfate ions present

Question 31

How do you test for halides

Answer 31

Add dilute nitric acid. Add silver nitrate. Observe precipitate.

Question 32

What colour precipitate is iodide

Answer 32

Yellow

Question 33

What colour precipitate is bromide

Answer 33

Cream

Question 34

What colour precipitate is chloride

Answer 34

White

Question 35

What happens to electrons when energy is added

Answer 35

They absorb the energy and go into the excited phase. Moving to different shells

Question 36

What happens after the excited phase from the electrons

Answer 36

Energy is emitted

Question 37

What is flame emission spectroscopy used for

Answer 37

Analyses metal ions in solutions

Question 38

Why cannot flame tests be used for two metal ions

Answer 38

The flame gives out one colour there may be other elements that are masked by others

Question 39

Describe the spectroscope

Answer 39

Distinct spectral lines corresponding to the wavelength emitted