Chemistry Year 10 Flashcards
What is thermal decomposition?
The breaking down of substances using heat
What do you observe when copper carbonate is heated through like water?
- colour green — black
- gas was evolves as lime water turned milky which indicates presence of CO2.
- the thermal decomposition was very easy.
What observations will you make when heating calcium carbonate through limewater?
- colour shiny white — dull white
- a little has was evolved
- needed a lot oh heat for thermal decomposition
What is observed when heating sodium carbonate through lime water?
- colour NO - NO
- NO gas evolved
- very difficult to thermally decompose.
What the formula and uses for limestone?
- CaCO3
* building, cement production, glass
How does limestone turn into quicklime?
Thermal decomposition of the lime water which releases CO2 and CaO(quicklime)
CaCO3 —> CaO + CO2
What the formulas and uses for quicklime?
- CaO
* used to make plaster or cement.
How does quick lime turn to slake lime?
•add a small amount of water
CaO + H2O -> Ca(OH)2
•the hydration of quicklime to slaked lime is highly exothermic (releases heat)
What is the formula for slaked lime and what is it used for?
- Ca(OH)2(s)
* neutralising soils
How does slaked lime turn into lime water?
Add lots of water
Ca(OH)2(s) —> Ca(OH)2(aq)
What do the formula for limewater and what is it used for?
- Ca(OH)2(aq)
* carbon dioxide test
How do you turn limewater to limestone?
Bubble in CO2
Ca(OH)2(aq) + H2O —> CaCO3 + H2O
What is the limestone cycle?
Limestone (calcium carbonate ) —> Quicklime (calcium oxide)—> slaked lime (calcium hydroxide solid) —> lime water (calcium hydroxide liquid)
What are the advantages of limestone quarrying?
- Provides jobs
- money for the economy
- provides an important resource
What are the disadvantages of limestone quarrying?
- destruction of scenic areas
- Lorrie create noise and dust pollution
- destruction of natural habitats
What are the 4 main structures of the earth?
Solid iron core, molten iron core, mantle and crust
What was Alfred Werner’s continental drift theory?
That all the continents used to be joined together in a supercontinent called Pangaea and that the earths crust and upper mantle was made of sections that drifted apart over years
Why was his idea of continental drift only accepted as a theory in 1960?
Because there was no explanation to how the continents could move until the evidence that tectonic plates existed in 1960
What was Wegebers evidence for continental drift?
- the continents coast lines fit together like a jigsaw
- similar fossil distribution across continents
- similar rock distributions of the same age at the location where two continents would have been joined
What is the tectonic plate theory?
The idea that the earth lithosphere is divided into separate parts know as tectonic plates, that move hover the mantle at a rate of a couple of centimetres per year, in a process called continental drift.
How is convection currents connect to plate tectonics and continental drift?
As the core heats the mantle it creates convection currents under the earths crust. The way the convection current moves for each plate shows what direction the plates move.
What happens at a destructive plate/ margin?
More dense oceanic plate subducts beneath the less dense continental plate and it melts as its near the mantle. It then re-emerges elsewhere as new igneous rock. The continental plate is deformed to form a mountain range .
What happens at a constructive margin?
The plates move apart, then the magma rises to fill the gaps. It then freezes and solidifies to form new “igneous” rock.
What happens at a conservative margin?
The plates slide past each other. They get caught by friction and strain builds. It then releases and jumps causing earthquakes.
Where do scientists think Earths first atmosphere came from?
Volcanic eruptions
What gases made up the first atmosphere?
Carbon dioxide, water vapour, methane, ammonia, argon.
How did the first oceans form?
When the earth cooled the water vapour condensed.
In the next 2 billion years after the earths atmosphere was formed where did most the carbon dioxide end up?
Lime stone and chalk
What living things evolved on Earth next?
Green plant
In the next 2 billion years after the earths atmosphere was formed what gas was removed from the atmosphere?
Carbon dioxide
In the next 2 billion years after the earths atmosphere was formed what gas did they add to the atmosphere?
Oxygen