Unit 2, topic 3 CHEMICAL REACTIONS Flashcards
(27 cards)
During a reaction, energy is …… to break the bonds in the reactants.
Taken in
What are the tell tale signs of a chemical reaction? (4)
1) Permanent colour change
2) Formation of a precipitate
3) Gas production
4) Temperature change. Up or down.
Energy is ………….. when new bonds form to make the products.
Given out
What reactions are exothermic? (4)
1) Combustion of fuels
2) Neutralisation
3) Displacement reactions
4) Hydration of copper sulfate
Example of endothermic reaction?
Thermal decomposition
What is thermal decomposition?
Thermal decomposition is the breakdown of a compound using heat.
Advantages of quarrying: (3)
1) Provides jobs
2) Provides raw material
3) Brings prosperity to local area
Disadvantages of quarrying (5):
1) Destroys natural habitat
2) Air pollution
3) Noise pollution
4) Land permanently unreplaceable
5) Dangerous
What is a redox reaction?
A reaction in which oxidation and reduction occur at the same time.
What is reduction?
The removal of oxygen or the addition of hydrogen.
What is oxidation?
The addition of oxygen or removal of hydrogen.
How is excess hydrogen disposed of safely?
By burning it off.
What is combustion?
Combustion is the reaction with oxygen, so by definition all examples of combustion are oxidation reactions.
What’s the formula for the production of iron in the blast furnace:
Iron oxide + carbon monoxide = iron + carbon dioxide
Rusting is an example of what?
Oxidation
How is water commonly removed from test tubes?
anhydrous calcium chloride
What conditions are needed for iron to rust?
Oxygen and water
What is the chemical name for rust?
Hydrated iron (III) oxide
What effect does salt have on rusting?
It increases the rate.
How can rusting be prevented (5)?
1) Painting
2) Oiling
3) Plastic coating
4) Metal Plating
5) Sacrificial protection
What is sacrificial protection?
The process of attaching a more reactive metal such as magnesium or zinc to the iron. Magnesium or zinc react before iron.
What is galvanising?
Galvanising is dipping iron in zinc. This creates double protection from sacrificial protection and physical barriers.
What happened during the first billion years of the earth’s existence?
Vocanoes happend
What is the composition of the atmosphere?
80% nitrogen and 20% oxygen.
There is also a small number of other gases such as carbon dioxide, water vapour and noble gases.
