KS3 Science

1. Reactivity and Rates of Reaction
By : Albert Ng

2. THE MYSTERY
OF
SPONTANEOUS
COMBUSTION

3. Learning Objectives
 How metals react with oxygen
 How metals react with water
 How metals react with acids
 Displacement reactions
 The reactivity series
 Measuring rate of reaction by change in mass of the
reactants
 Measuring rate of reaction by the change in volume of
the product
 The effect of concentration
 The effect of particles size
 The effect of temperature
 Catalysts

4. Metal
 Mostly active
 Combined readily with non metals such as oxygen to
form stable compounds
 Example of Metals:
 Aluminium
 Iron
 Lead
 Tin
 Silver
 Gold
 Nickel

5. Sodium
 Silver-white, highly reactive metal
 Need to be kept under a layer of oil because it
readily react wit water and oxygen in the air to
produce flames
 Very soft metal
 Shiny surface of small cut sodium quickly tarnished
soon it react with air

6. Comparatively, iron take much longer to react with
air ( Rusting of Iron )
 INDICATION:
Different metals have different speeds at which they react
with other chemicals = Different Reactivity

7. Reaction of metals with oxygen
 Why most metals lose their lustre over time?
 Metals react with oxygen in the air to form metal oxide.
This process is called oxidation
Metal + Oxygen  Metal Oxide
Example:
Iron + Oxygen  Iron Oxide

8. When metals heated with oxygen
 A) Copper develop a covering of black powder
without glowing or bursting into flame
 B) Iron glows and produces yellow sparks, a black
powder is left behind
 C) Sodium only needs a little heat to make it burst
into yellow flame and burn quickly to leave a white
powder behind
 D) Gold is not changed after it has been heated and
then left to cool

9. Reaction of metals with water
 Pg 147
Rocksil wool
soaked in water
Metal
Sample
Rubber Bung
Hydrogen
Water
Heat

10. Calcium
 A) In COLD water
 Sink
 Form bubble of hydrogen on its surface
 Bubbles increase over time
 Water become cloudy as calcium hydroxide formed
B) Test tube filled with water over fizzing metal
 Gas pushes water out of the test tube
 Tube filled with gas and raised out from water with a light
splint held beneath its mouth
 Popping sound heard because hydrogen in tube react
with oxygen in the air

11. Copper
 Sink in cold water and does not react with it
 Does not react with steam

12. Sodium
 Floats on surface of the water
 Bubbles of hydrogen produced around it (Fizzing)
 Gas produced push the metal across the surface
 Metals burst into flame
 Clear solution of sodium hydroxide formed
 VIDEO

13. Iron
 Sinks in water
 No bubbles of hydrogen formed
 When steamed, hydrogen produced slowly

14. Magnesium
 Sinks in water
 Bubbles of hydrogen produced very slowly
 Magnesium hydroxide solution formed
 When heated with steam, hydrogen is produced
quickly

15. Potassium
 Floats on water
 Bursts into flames immediately
 Hydrogen bubbles rapidly produced around the
metal
 Clear solution of potassium hydroxide formed

16. Reaction of metals with acids
 Pg 149
 Piece of metal placed in tube
 Acid was poured into the tube
 Bubble of hydrogen gas observed
 Reactivity of Metals can be compared by comparing the amount of
hydrogen gas produced in the reaction between acid and different
metals
 Metal+ Hydrochloric Acid  Metal Chloride + Hydrogen

17. Apparatus used in investigating the reaction of some
metals (Not sodium or potassium) and hydrochloric acid
Refer to Page 149

18. Reaction of metals with dilute HCL and Concentrated HCL
 Lead
 Did not react with dilute HCL
 Bubbles of hydrogen gas produced slowly
 Zinc
 React slowly with dilute HCL to produce bubbles of hydrogen
 Copper
 Did not react with either dilute or concentrated HCL
 Magnesium
 React quickly with dilute HCL to produce bubbles of hydrogen

19. Reactivity Series