C5

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  • Created by: Ola182
  • Created on: 29-05-17 16:24
Name a gas in dry air that is a compound. Give a formula of this gas.
Carbon dioxide
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Explain why most molecular substances are gases.
Because they have low melting and boiling points and weak forces of attraction
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What is covalent bonding?
When atoms share electrons in order to have a full outer shell of electrons
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What is the Earth's hydrosphere?
All the water on the earth - oceans, rivers and puddles
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What makes sea water salty?
The earth's hydrosphere contains compounds that are dissolved in water many of which are ionic compounds called salts.
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Why do solid ionic compounds form crystals?
Ionic compounds form giant lattices because ions with opposite charges are strongly attracted to one another. Each crystal is one giant ionic lattice.
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Do solid ionic compounds have low or high boiling points? Why?
They have high melting and boiling points because the forces of attraction are so strong it takes a lot of energy to overcome them.
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Why can ionic compounds conduct electricity when dissolved in water but not when they're solid?
When ionic compounds dissolve, their ions separate and are free to move in the solution. This means they are able to carry an electric current.
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Carbonates give off carbon dioxide when they're mixed with dilute acid. What's the test for carbon dioxide?
Carbon dioxide turns limewater cloudy signifying you've identified as carbonate ion.
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What's the test for sufates?
You add hydrochloric acid to remove traces of carbonate ions and then add barium chloride solution. If a white precipitate of barium sulfate is formed, the original compound was a sulfate.
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What's the test for halides?
Add dilute nitric acid (gets rid of carbonate ions) followed by silver nitrate solution. White=chloride, cream=bromide and yellow=iodide
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What colour precipitate does a solution containing iodide ions produce in the halide test?
A yellow precipitate of silver iodide
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What is the Earth's lithosphere?
The earth's crust and part of the mantle below it.
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Name three abundant chemicals in the Earth's lithosphere.
Silicon, oxygen and aluminium
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Industrial diamonds are used in drill tips and precision cutting tools. What property of diamond makes it suitable for this use?
It's strong.
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Explain how bonding in diamond gives it this physical property.
Each carbon atom forms four covalent bonds in a very rigid giant covalent structure.
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Graphite conducts electricity, which is unusual for a non-metal. Explain why it has this property.
Because each carbon only forms three covalent bonds leaving one electron per carbon atom spare. There are so many free electrons that graphite can conduct electricity.
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What is an ore?
Ores are rocks with materials that can be extracted from such as metal.
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Name a metal that can be extracted by reducing its oxide with carbon.
Iron, copper or zinc
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What is electrolysis?
The decomposition of a substance using electricity.
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Why can a molten ionic crystal act as an electrolyte?
Because the free ions in molten ionic crystals conduct electricity
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Describe what happens at the electrodes during the electrolysis of molten aluminium oxide.
Electrons are taken away from ions at the positive electrode and given to other ions at the negative electrode. As ions gain or lose electrons they become atoms or molecules.
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What do the terms reduced and oxidised mean?
When a metal oxide loses its oxygen it's reduced. The carbon gains the oxygen and is oxidised.
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Why are metals able to conduct electricity?
The free electrons carry heat and electrical current through the material
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Why have metals got high melting and boiling points?
Metallic bonds are very strong so it takes a lot of energy to break them.
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What impact does extracting metals have on the environment?
It uses lots of energy from burning fossil fuels, scars the landscape and destroys habitats
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What impact does disposing of metals have on the environment?
Metal would be sent to landfill which takes up space and pollutes the surroundings
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Give two reasons why it's a good idea to recycle metals.
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Other cards in this set

Card 2

Front

Explain why most molecular substances are gases.

Back

Because they have low melting and boiling points and weak forces of attraction

Card 3

Front

What is covalent bonding?

Back

Preview of the front of card 3

Card 4

Front

What is the Earth's hydrosphere?

Back

Preview of the front of card 4

Card 5

Front

What makes sea water salty?

Back

Preview of the front of card 5
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