C5 - Chemical Changes

Question 1

The reactivity series

Answer 1

Potassium, sodium, and calcium are at the top with transition metals such as gold and silver at the bottom

Question 2

Displacement reactions

Answer 2

When a more reactive metal displaces the less reactive metal

Question 3

Extracting metals

Answer 3

The less reactive metals are usually extracted by carbon reduction (heat a metal with carbon) (redox reaction)

More reactive metals are extracted by electrolysis

Question 4

Making salts

Answer 4

Salts are the compounds formed when acids are neutralised

Question 5

Bases (alkalis)

Answer 5

Bases are chemicals that neutralise acids to make a salt and H2O

Question 6

Reaction of metal with acids

Answer 6

Metal + acid = salt + hydrogen

Question 7

Reaction of metal oxides with acids

Answer 7

Metal oxide + acid = salt + H2O

Question 8

Reaction of metal carbonates with acids

Answer 8

Metal carbonate + acid = salt + CO2 + H2O

Question 9

Neutralisation reaction

Answer 9

A reaction between an acid and a base (alkalis)

Acids are in solutions of H+ ions

Alkalis are in solution of OH- ions

Question 10

Neutralisation reaction balanced equation

Answer 10

H+(aq) + OH-(aq) → H2O(l)

Question 11

Dilute solutions

Answer 11

A dilute solution contains relatively small amount of dissolved solute

Question 12

Concentrated solutions

Answer 12

A concentrated solution contains a relatively large amount of dissolved solute

Question 13

Strong acids

Answer 13

Strong acids completely dissociate into ions (H+) in solution

It ionises completely

Question 14

Weak acids

Answer 14

Weak acids partially dissociate into ions (H+) in solution

It partially ionises

Question 15

pH and hydrogen ion concentration

Answer 15

The higher the concentration of H+ ions in an acidic solution, the lower the pH

The lower the concentration of H+ ions in an acidic solution, the higher the pH