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iGCSE Chemistry: Metals & Reactivity - core

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(Triple only) Draw a diagram to show the bonding in a metal
(Triple only) Describe the bonding in a metal
The strong electrostatic attraction between a regular structure of positive metal ions and a sea of delocalised electrons
(Triple only) Explain why metals are good conductors of electricity
Metals have delocalised electrons which are free to move
(Triple only) Explain why metals are malleable
Metals have layers of ions that can slide over each other
(Triple only) What does the word malleable mean?
able to be hammered or pressed into shape without breaking or cracking
(Triple only) Why do metals have high melting and boiling points?
There is a strong electrostatic attraction between a regular structure of positive metal ions and a sea of delocalised electrons
State the names of the gases present in air and their % by volume
nitrogen = 78%. oxygen = 21%. argon = 0.96%. carbon dioxide = 0.04%
Describe a way in which the rusting of iron could be used to show the approximate percentage of oxygen in air
An excess of wet iron filings in left in a closed system with a known volume of air. After several days the volume of air has fallen as the oxygen is used up. The percentage of oxygen in air is calculates as the change in volume of gas divided by the initial volume (x100%)
Describe how the oxidation of copper can be used to show the approximate percentage of oxygen in air
With gas syringes in a closed system, air is passed back and forward over hot copper until the oxygen is used up. When the volume of gas stops decreasing, the percentage by volume of oxygen in the air is calculated as the change in the volume of gas divided by the initial volume (x100%)
Describe how the reaction of hydrochloric acid and various metals could be used to determine the relative reactivity of those metals
Add the various metals to different test tubes containing the same volume and concentration of acid. The metals which bubble more are more reactive.
An experiment investigates which of metals X and Z is more reactive. The result is X + ZSO₄ → X + ZSO₄. Which metal is more reactive?
Z. There is no reaction.
An experiment investigates which of metals X and Z is more reactive. The result is X + ZSO₄ → XSO₄ + Z. Which metal is more reactive?
X. This is a displacement reaction.
Order these metals from the most reactive to the least: aluminium, calcium, copper, gold, iron, lithium, magnesium, potassium, silver, sodium, zinc
potassium, sodium, lithium, calcium, magnesium, aluminium, zinc, iron, copper, silver, gold
Describe the conditions under which iron rusts
oxygen and water
Write the word equation for the formation of rust
iron + oxygen + water → hydrated iron (III) oxide
Explain how galvanising prevent rusting
Zinc is more reactive than iron. Zinc reacts with oxygen instead of iron
What is galvanising?
When zinc is used to coat a less reactive metal to prevent that metal from corrosion
State the methods of how the rusting of iron may be prevented
grease, oil, paint, plastic and galvanising
What is sacrificial protection?
Sacrificial protection is when a more reactive metal is connected to a less reactive metal. Only the more reactive metal corrodes, so protecting the less reactive metal
Explain why rusting is described as an oxidation reaction
iron gains oxygen
If a substance gains oxygen in a reaction how is the process described?
Oxidation
If a substance loses oxygen in a reaction how is the process described?
Reduction
State the meaning of the term redox
A reaction involving both reduction and oxidation
State the meaning of the term reducing agent
A substance that takes oxygen (it is itself oxidised)
What is it called when a metal reacts with oxygen in the air to form an oxide layer?
Oxidation
What is reduced in this equation and what is meant by reduction? WO₃ + 3H₂ → W + 3H₂O
Tungsten, W loses oxygen
Write the word equation to represent the reaction between hydrochloric acid and calcium
hydrochloric acid + calcium → calcium chloride + hydrogen
Write the word equation to represent the reaction between sulfuric acid and magnesium
sulfuric acid + magnesium → magnesium sulfate + hydrogen
(Triple only) State 2 properties that makes aluminium suitable for manufacturing aircraft
Low density & resists corrosion
(Triple only) Apart from being a mixture of metals, what non-metal is often added to alloys to make them stronger?
Carbon
(Triple only) What is an alloy?
An alloy is a mixture of a metal and one or more elements, usually other metals or carbon
(Triple only) Alloys contain different sized positive ions. What properties does this give alloys compared to pure metals?
Alloys are harder and less malleable than pure metals
acid + alkali →
acid + alkali → salt + water
acid + base →
acid + base → salt + water
acid + metal →
acid + metal → salt + hydrogen
acid + metal carbonate →
acid + metal carbonate → salt + carbon dioxide + water
Describe the observations of the reaction of calcium carbonate and dilute hydrochloric acid
fizzing and solid disappears
Describe the observations of the reaction of magnesium and dilute sulfuric acid
fizzing and metal disappears
Give the formula of sulfuric acid
H₂SO₄
Give the name of the substance which has formula HNO₃
nitric acid
Give the name of the substance which has the formula HCl (aq)
hydrochloric acid
hydrochloric acid + magnesium →
hydrochloric acid + magnesium → magnesium chloride + hydrogen
hydrochloric acid + sodium hydroxide →
hydrochloric acid + sodium hydroxide → sodium chloride + water
nitric acid + calcium carbonate →
nitric acid + calcium carbonate → calcium nitrate + carbon dioxide + water
sulfuric acid + copper oxide →
sulfuric acid + copper oxide → copper sulfate + water
Identify the species that is oxidised in the following reaction. Explain your answer: 2Br⁻ + Cl₂ → 2Cl⁻ + Br₂
Bromide. Loses electrons
Identify the species that is reduced in the following reaction. Explain your answer: 2Br⁻ + Cl₂ → 2Cl⁻ + Br₂
Chlorine. Gains electrons
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