1. Lesson 12 Water and reactive metals
Y9 Chemistry Unit
Lesson 12
Water and reactive metals

2. Lesson Objectives
Write word equations of the chemical reactions of reactive metals (group 1 and 2) with water (Ca, K, Na, Mg)
9Fb p.70
Describe ways in which metals can be protected against corrosion from nitric acid, carbonic acid, and sulphuric acid
9Fc p. 72-3

3. Metals and water Some metals are very reactive Some metals are not
Ca, Na, Mg, K
Some metals are not
Au, Ag, Cu,
Reactive metals give off heat (exothermic) when reacted with water and can burn
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4. Reactions of metals with water
When a metal reacts with water hydrogen is always given off. The other product will be either a metal hydroxide or a metal oxide.
METAL + WATER METAL OXIDE + HYDROGEN
METAL + WATER METAL HYDROXIDE + HYDROGEN
Copy and complete the following reactions:
Sodium + water
Potassium + water
Calcium + water
Iron + steam
29/11/2018

5. Reactive Metals Are not found as pure elements in nature
They have reacted with water or oxygen or other elements to form compounds
NaCl, CaO, CaCl2, KBr, MgO, CaCO3
To separate these compounds electricity is used
Electrolysis
CaCO3

6. Review: metal reactions
Lithium + water
Lithium + hydrochloric acid
Silver + oxygen
Magnesium + sulphuric acid
Potassium + oxygen
Aluminium + oxygen
Manganese + water
Sodium + sulphuric acid
Lithium + oxygen
Nickel + hydrochloric acid
Lithium hydroxide + hydrogen
Lithium chloride + hydrogen
Silver oxide
Magnesium sulphate + hydrogen
Potassium oxide
Aluminium oxide
Manganese oxide + hydrogen
Sodium sulphate + hydrogen
Lithium oxide
Nickel chloride + hydrogen
29/11/2018

7. Acids in the Air
CO2, NO2 and SO2 in the air combine with water and make acids which corrode metals
carbonic acid
sulphuric acid
nitric acid

8. Acids in the Air
Metals react with acids to produce metal oxide and hydrogen
Metal statues and building structures need to be protected from corrosive acid rain
Some metal oxides provide their element with protective coat
Aluminum- stays about the same color
Copper- turns green

9. Protecting metals Galvanizing Plating
Use zinc carbonate to coat iron
Plating
Tin or nickel is used to cover the iron
Both methods are only temporary -over time the coats will erode

10. Factors that effect corrosion
Amount of acid rain (air pollution)
Increase CO2, NO2 and SO2 by
Car emissions (CO2)
Factory emissions (SO2, CO2 and NO2)
Volcanoes (CO2 and SO2)
Lightening (NO2)

11. Factors to know Natural rain has a pH of 5.6
Acid rain has a pH of less than this
Zinc coating is called a sacrificial protection because it reacts with oxygen and/or water before the iron

12. Think About Natural pollution (p. 80-81)
What effect can a large volcanic eruption have
on the average world temperature
on crops and food production
Write your ideas in your notebook

13. Tasks P. 33 in Chemistry Booklet P. 34-5 in Chemistry Booklet
Read the information and organize the metals in order of reactivity from least to most
P in Chemistry Booklet
Read and complete 1-4,
ask your teacher if you do not understand how to graph the data
HW: complete page 37 in Chemistry Booklet
“Quick Check”