What gas makes up around 1% of Earth's atomosphere?
What percentage of the Earth's atomosphere is oxygen?
Draw a gas syringe
With gas syringes in a closed system, 200cm³ of air is passed back and forward over hot copper until the oxygen is used up. At the end, 160cm³ remains. Calculate the percentage by volume of oxygen in the air.
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.
If 2 similar test tubes contain acid, and a different metal sample is added to each, how might you tell which metal is more reactive?
More bubbles will appear faster in the test tube with the more reactive metal
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
Describe an experiment to show that iron rusts quicker in salt water than rain water
1) Set up tubes containing iron in rain water and in salt water. 2) Set up control tube with iron and no water. 3) record mass of nails. 4) leave tubes for same length of time. 5) measure mass change of nail. 6) repeat experiment
Describe the conditions under which iron rusts
oxygen and water
Do metals other than iron rust?
No. The term rust is only applied to iron
What is the chemical name of rust?
hydrated iron(III) oxide
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?
If a substance loses oxygen in a reaction how is the process described?
Is the production of iron from iron ore oxidation or reduction?
State the meaning of the term oxidising agent
A substance that gives oxygen (it is itself reduced)
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?
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