C12-chemical Analysis

Question 1

Pure in advertising

Answer 1

Nothing added to it

Question 2

Pure in chemistry

Answer 2

A pure substance is one that is made up of just one substance. That’s substance can be either an element or a compound.

Question 3

What can you use to identify pure substances?

Answer 3

Boiling and melting points (of an element or compound are called fixed points)

Question 4

What do impurities tend to do?

Answer 4

Lower the melting point of a substance and raise its boiling point

Question 5

What is a formulation?

Answer 5

Is a mixture that has been designed to produce a useful product

Question 6

What is the Rf formula

Answer 6

Distance moved by substance/ distance moved by solvent

Question 7

How do you test for hydrogen?

Answer 7

The reaction between zinc and dilute acid is a convenient way to make some hydrogen gas to test.
Hold a lighted splint at the open end of the test tube of hydrogen gas
A lighted splint pops
Few crystals of copper sulfate act as a catalyst

Question 8

How to make oxygen

Answer 8

Hydrogen peroxide with magenese oxide as a catalyst makes water + oxygen

Question 9

How to test for oxygen?

Answer 9

A glowing splint relights

Question 10

How do you make carbon dioxide?

Answer 10

By reacting calcium carbonate and dilute hydrochloride acid to make calcium chloride + water + carbon dioxide

Question 11

How to test for carbon dioxide

Answer 11

Bubble carbon dioxide gas through like water (calcium hydroxide solution)
Lime water turns cloudy white

Question 12

Testing for chlorine gas

Answer 12

Add concentrated hydrochloric acid to a spatula of moistened potassium manganate crystals in a boiling tube held in a rack inside a fine cupboard
Damps blue litmus paper turns white as it gets bleached

Question 13

How to do the flame test?

Answer 13

Nichrome wire loop should be dipped in concentrated hydrochloric acid and then heated to clean it first. Dipped in the acid again before dipping it into the metal compound.
Thé. Hold the loop in the roaring blue flame of a Bunsen burner

Question 14

Metal ions for 
Crimson 
Yellow 
Lilac 
Orange red 
Green

Answer 14

Lithium Li+ crimson 
Sodium Na+ yellow 
Potassium k+ lilac
Calcium Ca2+ orange red 
Copper cu 2+ green

Question 15

How to test for positive ions

Answer 15

Add sodium hydroxide solution

Question 16

What do magnesium calcium and aluminium all form when a sodium hydroxide is added

Answer 16

A white precipitate

Question 17

What redissolves when add excess sodium hydroxide solution

Answer 17

Aluminium precipitate

Question 18

How can calcium and magnesium ions be distinguished?

Answer 18

Flame test
Calcium orange red
Magnésium no colour at all

Question 19

Coloured precipitates

Answer 19

Copper II ions a blue precipitate
Iron II ions a green precipitate
Iron III a brown precipitate

Question 20

Test for carbonate ion

Answer 20

Add dilute acid
Acid will react with the carbonate to make carbon dioxide gas see fizzing
Magnesium carbonate + hydrochloric acid makes magnesium chloride + water + carbon dioxide

Question 21

Test for halide ions

Answer 21

Add dilute nitric acid to the sample
Add dilute silver nitrate solution
Valide ions produce a precipitate of silver halide

Question 22

Precipitate colours
Chloride ions
Bromide ions
Iodide ions

Answer 22

White precipitate 
Cream precipitate 
Yellow precipitate
Silver chloride 
Silver bromide 
Silver iodide

Question 23

Test for sulfate ions

Answer 23

Add dilute hydrochloric acid
Add barium chloride solution
Sulfate ions are présent you will see a white precipitate