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50 Cards in this Set
- Front
- Back
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What was the early atmosphere of the Earth formed from? |
Gases that were released in volcanic eruptions |
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What were the main gases in the early atmosphere and how do we know? |
Carbon dioxide and water vapour, as these gases are still produced by volcanoes today |
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How can scientists use rocks to study the early atmosphere? |
Rocks contain a record of the gases in the atmosphere at the time that they formed. Scientists can analyse rocks that formed at different times to see how the atmosphere has changed |
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What is one of the most reactive gases in the atmosphere and how can we see this? |
Oxygen. Oxidation reactions can happen, for example rusting metals is caused by oxygen reacting with the metal and maintenance of fire requires oxygen |
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How do rocks show us that the level of oxygen in the atmosphere has changed? |
Recent rocks contain iron oxide, but ancient rocks contain less. This shows that levels of oxygen have increased as recent rocks contain more |
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What were the other two dramatic changes in gas levels? |
Carbon dioxide dropped and nitrogen levels increased |
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What happened as the earth cooled and how did this change the atmosphere? |
Water vapour in the air condensed and formed oceans. Carbon dioxide dissolved in these oceans and sea animals took it in to make carbonate shells. Sea plants also used it for photosynthesis which released more oxygen into the atmosphere. |
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What are the percentages of gases in today's atmosphere? |
78% nitrogen 21% oxygen 1% argon 0.03% carbon dioxide tiny amounts of other gases |
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How do we calculate the percentage of oxygen in the air? |
By measuring how much iron oxide is formed when iron is placed with a known volume of air |
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What causes gas levels in the atmosphere to change? |
Volcanic eruptions, burning fossil fuels and deforestation |
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How does the level of carbon dioxide increase? |
Burning fossil fuels releases lots of CO2, as do volcanic eruptions. Also, deforestation removes plants which take away CO2, so levels decrease less. |
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What happens to atoms in a chemical reaction? |
None are created or destroyed, only bonded or broken apart |
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What must you do to a symbol equation and how? |
Balance the products and reactants by changing the coefficient of each compound |
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How does igneous rock form? |
When molten magma or lava cools and solidifies |
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What are the two types of igneous rock and how are they different? |
Extrusive - formed on the earth's surface quickly and has lots of small crystals Intrusive - formed inside the earth slowly so has a few large crystals |
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How are sedimentary rocks made? |
When tiny particles called sediment settle on the ocean floor in layers. As more layers build up, there will be more pressure on those underneath so the layers combine into a rock |
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How is metamorphic rock formed? |
When sedimentary rocks are deep enough underground that they are subjected to extreme heat and pressure, it causes arrangement of layers and crystals to change and form a new rock (metamorphic) |
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Why do intrusive and extrusive igneous rocks cool slowly or quickly? |
Intrusive rocks cool slowly as they are buried within the earth so are closer to the hot core, and the heat stops them cooling quickly. Extrusive rocks are outside the surface, so there is less heat, and instead, air which causes them to cool faster. |
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How are crystals formed in rocks? |
When atoms or molecules fit together in rigid structures with regular particles layers |
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Why, relating to kinetic energy, does the speed of cooling affect the size of crystal in igneous rocks? |
Hotter temperatures cause more kinetic energy in the atoms. When cooling happens, the atoms lose this kinetic energy. If cooling is slow, atoms gradually settle and join onto one another to make a few large crystals. If cooling is fast, atoms stop moving sooner, so they settle anywhere in the rock instead of joining together so lots of small crystals are formed |
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How does weathering cause the production of sedimentary rocks? |
Weathering breaks rocks into fragments which are transported to the ocean by rivers. Over time, compaction happens and the fragments are squashed together into rocks |
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What do chalk and limestone form when under heat and pressure? |
The metamorphic rock limestone |
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How do fossils form in sedimentary rock? |
Organisms fall into sediment but there isn't enough oxygen to cause it to decay. If it has hard enough parts, it will leave a caste in the forming rock, and water filtering through will deposit minerals in it |
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How are rocks eroded and by what? |
They can be eroded by wind and water which produces small fragments, with which sedimentary rocks are made. Over time, these rocks can be uplifted and once again exposed to wind and water which causes more erosion |
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What is the important chemical in limestone and why do we need to quarry it? |
Calcium carbonate, which can be used to make glass, cement and concrete |
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How are glass, cement and concrete made? |
Glass - heating limestone, sodium carbonate and sand Cement - heating limestone and clay Concrete - mixing sand, gravel, cement and water |
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What are the advantages and disadvantages of quarrying limestone? |
Adv - provides jobs for those near the quarry - industries using limestone are important for the national and local economy Dis - creates noise, dust and damage animal habitats - transporting it causes traffic congestion, and environmental and road damage |
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What are five ways we can minimise the problems of quarrying? |
- Restrict size of quarries - Only blasting at specific times - Use water sprays to keep dust down - Create earth barricades to reduce noise - Factor in the reclamation of land after closing the quarry |
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What do chemical properties show? |
How something behaves in a reaction |
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What are some examples of physical properties? |
Viscosity, hardness, density, melting point, colour, magnetism, solubility |
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What is a precipitation reaction? |
A reaction in which two liquids react to form a solid |
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What will happen to the mass if a reaction takes place in a sealed container? |
The mass will be unchanged as no products can escape |
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What is conservation of matter (or mass)? |
The rule that in all reactions, no matter is made or destroyed; it is all just transferred into other forms
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How can conservation of mass be used to calculate the amount of oxygen in iron oxide? |
- Weigh a sample of iron - Heat it with a known volume of air (forming iron oxide) - The mass of the iron oxide - the mass of the iron = the mass of oxygen |
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What happens in a thermal decomposition reaction? |
A chemical compound is broken down into its separate elements by heating |
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What is the pattern that shows the thermal decomposition of a metal carbonate? (With examples) |
Metal Carbonate-->Metal Oxide+Carbon Dioxide E.g. Zinc Carbonate-->ZincOxide+Carbon Dioxide CopperCarbonate->CopperOxide+CarbonDioxide |
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What is calcium oxide used for? |
Making glass, cement and limewater |
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How is slaked lime produced? |
When calcium oxide and water react, calcium hydroxide is produced (slaked lime). The reaction gives off a lot of heat. Equation: CaO + H2O ---> Ca(OH)2 |
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What is limewater and what happens when it reacts with carbon dioxide? |
It is calcium hydroxide solution. Carbon dioxide makes it go cloudy as a solid white precipitate forms (calcium carbonate). Equation: Ca(OH)2 + CO2 ---> CaCO3 |
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What are some uses of the metal oxides zinc oxide and copper oxide? |
ZnO - rubber, concrete, medicine, cosmetics CuO - pigments, semiconductors |
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What pH soil is best for crop growth and how can it be made to this pH) |
Neutral (pH 7). If it is too acidic, calcium carbonate, oxide or hydroxide is added as they are alkaline |
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What happens when fossil fuels are burnt in a power station and how can we stop it? |
They release harmful gases like sulphur dioxide, but a scrubber coated with calcium carbonate removes these gases before they leave the power station |
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What is a base? |
A compound that can neutralise acid in a neutralisation reaction |
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What is formed in a neutralisation reaction? |
A salt and water. acid + base ---> salt + water |
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What is formed if you neutralise an acid using a carbonate? |
A salt, water and carbon dioxide. acid+carbonate---> salt + water + carbon dioxide |
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What is an alkali? |
A soluble base |
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What does hydrochloric acid do in our stomach, what problems can it cause and how are they fixed? |
It kills bacteria and activates enzymes for digestion. However, it can cause indigestion if there is excess. This is fixed by using antacids, which neutralise the excess acid. |
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How can you work out how effective antacids are? |
Measure how much acid they can neutralise by doing a titration reaction, slowly adding acid to the tablet until no more acid iss neutralised |
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What pH do acids and alkalis have? |
pH goes from 1-7. 7 is neutral. Less than 7 is acidic, and more than 7 is alkaline |
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How can a salt be named? |
The first word comes from the metal in the base, and the second from the acid. Hydrochloric acid = chloride Sulphuric = sulphate Nitric = nitrate |
