chemical changes

Question 1

metal + oxygen

Answer 1

metal oxide

Question 2

oxidation

Answer 2

when oxygen is added, or when electrons are lost

Question 3

reduction

Answer 3

when oxygen is lost, or when electrons are gained

Question 4

reactivity series order

Answer 4

potassium, sodium, lithium, calcium, magnesium, carbon, zinc, iron, hydrogen, copper, silver

Question 5

reactivity of metals with water

Answer 5

metals aove hydrogen in reactivity series will react with hydrogen as it displaces the hydrogen to form metal hydroxide and hydrogen

Question 6

reactivity of metals with acid

Answer 6

metals above hydrogen will react with acid to form metal salt and hydrogen

Question 7

reactivity of metal and tendancy to form positive ion

Answer 7

more reactive metals have a higher tendancy to form positive ions therefore they react more vigourously with water and acid - eg potassium more vigourous reaction than magnesium

Question 8

ionic equation for reaction between copper sulfate and magnesium

Answer 8

Cu2+(aq) + Mg(s) -> Mg2+(aq) + Cu(s)

Question 9

ionic equation for neutralisation

Answer 9

H+(aq) + OH-(aq) -> H2O(l)

Question 10

how can metals less reactive than carbon be extracted?

Answer 10

by reduction with carbon. this involves the loss of oxygen

Question 11

what is a redox reaction

Answer 11

reduction and oxidation happens in same reaction - metal and acid reactions are redox reactions

Question 12

Zn + 2HCl ⟶ ZnCl2 + H2

ionic equation and half equation

Answer 12

ionic equation:
Zn + 2H+⟶ Zn2+ + H2

half equation:
Zn → Zn2+ + 2e–
2H+ + 2e–→ H2