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How was carbon dioxide reduced from the earth's early atmosphere?
- 1. The CO2 gets dissolved in sea water and creatures use it to create their shells of calcium carbonate. Once the animals die, their shells are compressed to form limestone.2. Carbon dioxide is taken in by organisms that have grown because of the water.
What are the gases thought to have been in the earth's early atmosphere?
Mostly carbon dioxide and a little nitrogen but no oxygen.
Which planet(s) do scientists think the earth's early atmosphere was most like? Why?
Mars and Venus because they both have rocky interiors and volcanoes.
What is the main substance in limestone?
What is the composition of the atmosphere?
- Nitrogen - 78%
- Oxygen - 21%
- Argon - 0.9%
- Carbon Dioxide - 0.04%
- Other gases - traces
What are the main features of igneous rocks?
- Can have large or small crystals.
- Randomly arranged crystals.
What are the main features of metamorphic rocks?
- Hard rocks with tightly interlocking crystals.Can see layers.
What are the main features of sedimentary rocks?
- Some rocks can see bits of sediment and fossils.Grains are small and rounded.
- Soft rock.
Examples of igneous rocks.
Examples of metamorphic rocks.
- Marble - was chalk or limestone.
- Slate - was mudstone.
- Gneiss - was granite.
Examples of sedimentary rocks.
How are igneous rocks formed?
- Cooled magma.
- Small crystals = cooled quickly.
- large crystals = cooled slowly.
How are metamorphic rocks formed?
Heat/pressure changes crystal formation and produces a different rock.
How are sedimentary rocks formed?
sediments e.g. sea creatures are crushed and compressed together until they form rock.
Which type of rock is most easily eroded? Why?
Sedimentary because metamorphic and igneous rocks have interlocking crystals and are harder.
Name the 2 types of weathering.
Physical and chemical
How were the oceans formed?
Volcanoes gave out carbon dioxide and water vapour. Once the atmosphere cooled down, the water vapour condensed to form our oceans.
What are some of the uses of limestone?
- a building material
- cement - heated with clay in a kiln.
- concrete and mortar - mixed with sand, water and crushed rock.
- glass - heated with sand and sodium carbonate.
- used in toothpaste
- makes paper smooth
What is a problem when using limestone for building?
Acid rain reacts with limestone and dissolves it away.
What is the equation for the thermal decomposition of calcium carbonate?
- Calcium carbonate ---> Calcium oxide + carbon dioxide
What is limewater and how do you make it?
- The thermal decomposition of calcium carbonate makes calcium oxide, which reacts with water to produce calcium hydroxide. Calcium hydroxide dissolves in water to produce limewater.
- Calcium oxide + water ---> calcium hydroxide
How do you test for carbon dioxide?
bubbling a gas through limewater - if it turns milky, it is carbon dioxide.