C2a Topic 2 - Ionic Compounds and Analysis

Question 1

An ion is

Answer 1

An atom or group of atoms that have a charge

Question 2

Ions form..

Answer 2

1) A closely packed regular lattice arrangement.
2) This is because ionic bonds are very strong electrostatic forces of attraction between oppositely charged ions.
3) This gives ionic compounds similar properties.

Question 3

Ionic compounds share the following properties…

Answer 3

1) They have HIGH MELTING and BOILING POINTS - because of the very strong bonds between the ions. It takes a lot of energy to break these bonds.
2) The CONDUCT ELECTRICITY when MOLTEN or AQUEOUS - in an aqueous solution the ions separate and are all free to move, so they’ll carry electric current. The same happens when they melt - the ions are free to move and they’ll carry electric current.

Question 4

When 2 different elements combine the compound’s name is

Answer 4

‘something -IDE’

Question 5

When 3 or more different elements combine and one of them is OXYGEN, the compound’s name is often

Answer 5

‘something -ATE’

Question 6

Common salts of sodium, potassium and ammonium are

Answer 6

Soluble!

Question 7

Nitrates are

Answer 7

Soluble!

Question 8

Common chlorides are

Answer 8

Soluble (except silver chloride and lead chloride)

Question 9

Common sulphates are

Answer 9

Soluble (except lead, barium and calcium sulphate)

Question 10

Common carbonates and hydroxides are

Answer 10

Insoluble (except for sodium, potassium and ammonium ones)

Question 11

To make insoluble salts, we use __________ reactions

Answer 11

Precipitation

Question 12

Barium sulphate

Answer 12

Is an insoluble salt!

Question 13

Describe how you would make a pure, dry sample of barium sulphate

Answer 13

1) Mix solutions of barium nitrate and potassium sulphate (you want a soluble salt of barium “something”, and a soluble salt of “something” sulphate).
2) Filter out the precipitate of barium sulphate.
3) Wash it with distilled water.
4) Dry it on filter paper.

Question 14

Why is barium sulphate so useful

Answer 14

1) It is opaque to X-rays. When drunk it shows up the gut so that any problems can be seen.
2) Barium salts are toxic, but barium sulphate can be safely drunk because it’s insoluble. This means it isn’t absorbed into the bloodstream - it just passes through the body.

Question 15

Sodium ions produce a _________ flame

Answer 15

Yellow/orange

Question 16

Potassium ions produce a __________ flame

Answer 16

Lilac

Question 17

Calcium ions give a _________ ______ flame

Answer 17

Brick red

Question 18

Copper ions give a _______/_________ flame

Answer 18

Blue/green

Question 19

Flame tests work when you have

Answer 19

A sample of a pure element AND ALSO if you have a compound that contains that element!

Question 20

How should you clean the wire loop when doing flame tests

Answer 20

By dipping it in Hydrochloric acid and rinsing it with distilled water

Question 21

How can we test for Carbonates

Answer 21

1) Test for Carbon dioxide. You can do this by bubbling the gas through limewater. If the gas is carbon dioxide, the limewater turns cloudy!
2) This works because in a CASHOCO reaction carbonates react with dilute acids to form a salt + water + carbon dioxide!

Question 22

How can we test for Sulphates

Answer 22

1) Add dilute Hydrochloric acid, followed by barium chloride solution!
2) A white precipitate of barium sulphate means the original compound was a sulphate.

Question 23

How do we test for Chlorides

Answer 23

1) Add dilute nitric acid followed by silver nitrate solution!
2) A chloride gives a white precipitate of silver chloride!

Question 24

What method can we use to identify elements FOR CERTAIN

Answer 24

Spectroscopy

Question 25

Which groups are most likely to form ions

Answer 25

Groups 1&2 and 6&7