Chemistry C1 Flashcards
Cathode
Negative
Hydrogen only comes out here
What is produced by all acids in electrolysis
Hydrogen
Annode
Positive
Oxygen and chlorine only come out here
Electrolysis of hydrochloric acid
Decomposes into hydrogen and chlorine gas
At the annode, it bubbles and fills slowly with a green gas that bleaches damp blue litmus (chlorine)
At the cathode, it bubbles rapidly with a gas that burns with a squeaky pop (hydrogen)
Electrolysis
The breaking down of a compound using electricity
Electricity comes from a direct current source
Electricity is applied by 2 electrodes
Ores
An ore is a rock from which enough metal can be extracted to make a profit
Finite resource
The more reactive the metal is the harder it is to extract
Different ways to extract metals
Electrolysis- potassium, sodium, aluminium
Heating with carbon- zinc, iron, tin, lead
Oxidation
A chemical reaction in which an element or compound gains oxygen
Reduction
A chemical reaction in which an element or compound loses oxygen
Redox reaction
Where oxidation and reduction is taking place at the same time
Oxidising agent
Adds oxygen to another substance
Reducing agent
Takes away oxygen from another substance
Rusting of iron
Oxygen and water must be present
Things that encourage rusting
Acid
Copper
Slows down rusting
Magnesium
Alloys
Make metals better
Cannot write a formula for them
Mixture of two elements of which one is a metal
Smart alloys
Change their properties if the conditions change
Crude oil
- Mixture of hydrocarbons
- Each faction is NOT pure
- It’s a mixture so the different hydrocarbon molecules are not chemically bonded and keep their original properties
Lovely Ponies Neigh Proudly Down Fluffy Long Bridges
LPG- cooking, camping gas, lighters Petrol- fuel for cars Naphtha- making other chemicals Paraffin (kerosene) -jet fuel Diesel oil- large machines, trains Fuel oil- ships Lube oil- axel greases Bitumen-Tarmac, waterproofing houses, rooves
Complete combustion
When there is no limit to the amount of oxygen you have
Releases lots of energy and no harmful waste products
Clean blue flame
Fuel
A substance that releases usable energy
Hydrocarbons
Substances that contain only carbon and hydrogen joined together
Alkanes
- Made up of chains of carbon atoms with single bonds
- Saturated because no spare bonds
- Don’t turn bromine colourless (no spare bonds)
- Don’t form polymers
Methane - Ethane - Propane
Cracking
Splitting up long chain hydrocarbons to form alkenes
Thermal decomposition – uses heat
Polymerisation
Turning alkenes into long chains
3 phases of Atmosphere evolution
- Volcanoes gave out gases
- Green plants evolved and produced oxygen
- Ozone layer allows evolution of complex animals
Volcano gas release
- The earths surface was originally molten, any atmosphere boiled away
- Eventually a thin crust formed
- Volcanoes gave out lots of gas
- Oceans formed
Why were oceans formed?
Volcanoes gave out gas such as CO2 and Oxygen which condensed to create the oceans and atmosphere
Early atmosphere
Mostly CO2 with virtually no Oxygen
Green plants evolved and produced oxygen
- A lot of the CO2 dissolved into the oceans
- Marine organisms developed and took in the CO2, they died and were locked in carbonate rocks
- Green plants evolved taking in the CO2 and using photosynthesis to turn this into oxygen
Ozone layer allows evolution of complex animals
- Build up of oxygen killed of organisms that couldn’t take it but more complex organisms began to develop
- Oxygen created Ozone layer (O3) blocked harmful rays
- Little CO2
Today’s atmosphere
Atmosphere is still changing due to human and volcano activity.
Sources of information on the evolution of the atmosphere is limited
How is human activity changing the atmosphere?
- Burning fossil fuels releases CO2
- Deforestation contributes to rising CO2 less trees converting it
- Livestock farming releases huge amounts of methane
How is volcanic activity changing the atmosphere?
- Sulphur dioxide can be thrown high into the atmosphere when they erupt, this reacts with sunlight water and oxygen to form smog
- Carbon dioxide is released by volcanic eruptions
Why are information sources on the evolution of the atmosphere limited
- We’ve learned a lot from Antarctic ice cores. Bubbles of air get trapped in new layers each year
- However this must be precise as the changes are tiny
- Some is down to guesswork because no one was actually around at the time
Experiment to investigate the proportion of Oxygen in the atmosphere
- When heated copper reacts with the oxygen in the air
- If u heat an excess of copper and pass air over it using 2 syringes. You use the markers to find how much oxygen has been used up starting with 100cm3 of air
Chemical equation for oxygen proportion test
2cu + O2 –> 2CuO
Three types of rock
Sedimentary
Igneous
Metamorphic
Sedimentary
- Formed from layers of sediment laid down in lakes or seas
- Layers get pressed squeezing out the water
- Fluids flowing through pores deposit natural cement
Limestone and chalk
Metamorphic
- Formed from other rocks in pressure and heat over time
- Chemical composition= same as original
- Don’t actually melt
Marble
Marble
Formed from limestone or chalk
Very high temperatures break down limestone and reforms as small crystals
Igneous rocks
- When molten magma pushes up into the crust or through it before cooling and solidifying
- Various different minerals and randomly arranged interlocking crystals
Granite
Two types of igneous rocks
Extrusive
Intrusive
Extrusive
Igneous rocks cool quickly above ground
Small crystals
Basalt
Intrusive
Igneous rocks call slowly underground
Form big crystals
Granite
Limestone uses
Building material Statues Crushed up for road surfacing With powdered clay to make cement Glass Neutralise acidic soil
Advantages of limestone
- Many uses
- Neutralise sulphur dioxide
- Quarry provides jobs + brings money to local economy
- Once quarrying is complete restoration is required
Limestone disadvantages
- Acid rain erodes it
- Quarrying it makes ugly holes
- Quarrying process makes lots of noise and dust
- Destroys habitats of birds and animals
- Limestone needs to be transported away
- Waste materials produce tips
Limestone thermal decomposition
Calcium carbonate –> calcium oxide+ carbon dioxide
CaCO3–> CaO + CO2
Other carbonates decompose the same way
Thermal decomposition of carbonates
Zinc carbonate and copper carbonate thermally decompose in the same way as calcium carbonate to form an oxide and carbon dioxide
Less stable carbonates will decompose faster
Calcium oxide reaction with water
CaO + H2O –> Ca (OH)2 calcium hydroxide
Can be used to neutralise acidic soil
Dissolves in water to create limewater
Atoms aren’t lost or made in chemical reactions
They are just arranged in different ways to give new products
The mass is the same
Reaction in a sealed container
The total mass doesn’t change
Good example is a precipitation reaction
Eg copper sulphate and sodium hydroxide
Acid
Substance with a pH less than 7
Base
Insoluble alkali
Alkali
Substance with a pH greater than 7
Neutralisation between acids and bases
Forms salt and water
Products are neutral
Acid + base –> salt + water
Salt uses
Fertilisers- ammonium nitrate, ammonium phosphate
Fireworks as colouring agents
Stomach produces Hydrochloric acid
- Helps with digestion- enzymes work best in acidic environment
- Acid helps to kill bacteria prevents food poisoning
Indigestion is caused by
Too much hydrochloric acid in the stomach
Indigestion tablets contain bases such as calcium carbonate which neutralises the excess acid
Test how much acid a single tablet can neutralise
Crush up one dose and dissolve in a volume of water
Add three drops of indicator
Fill a burette with hydrochloric acid
When colour stays then stop
Work out volume of HCL it could neutralise
Metal oxides and metal hydroxides are often bases
This means they can be neutralised with acids to for, salt and water
The combination of mets, and acids decides the salt
Eg hydrochloric acid + copper oxide
—————–>
Copper chloride + water
What happens when carbonates neutralise acids
They give off CO2
Electrolyte
The solution in electrolysis
Test for chlorine
Bleaches damp blue litmus paper
Danger of chlorine
Chlorine is toxic
Three uses of chlorine
Treat water supplies
Needed for the manufacture of bleach
Used to make the polymer polychloroethene
Electrolysis of water
Gives hydrogen and oxygen
Test for oxygen
The gas will relight a glowing splint
Properties of metals
Strong
Bendy
Conductors
Aluminium
low density, corrosion resistant
Window frames, aircraft
Why do we make alloys
In order to make pure metals stronger and increase the uses
Why are alloys harder?
Different sized atoms so making it harder for atoms to slide over each other therefore the alloy is harder
Example of a smart alloy
Nitinol- nickel and titanium
Can be used for glasses frames
Incomplete combustion
When there isn’t enough oxygen
Carbon monoxide produced
Carbon produced
NOT SAFE
Choosing a good fuel
Ease of ignition
Energy value
Ash and smoke
Storage and transport
Environmental problems with burning fossil fuels
- if incomplete then carbon monoxide and Carbon produced
- Contains sulphur impurities so sulphur dioxide produced which causes acid rain
Acid rain
Caused by sulphur dioxide reacting with clouds to produce dilute sulphuric acid
Kills trees and damages buildings
Causes lakes to become acidic
Sulphur can be removed from fuels before they’re burnt
This takes more energy which takes more fuel which releases more CO2
Acid rain prevention
Acid gas scrubbers to take harmful gases out before they’re released
Cars have catalytic converters to clean up exhaust gases
Reduce use of fossil fuels
Carbon dioxide problems
Greenhouse gas so acts as an insulating layer keeping heat in
Affected by humans- respiration, burning trees, deforestation, fossil fuels
Biofuels
Biogas- microorganisms used to compose living organisms waste
Alcohol- eg ethanol made from sugar
However large amounts of land are needed where we could be growing food
How fuel cells work
Hydrogen and Oxygen give out energy when they react + it only produces water
Uses a fuel and oxygen to generate electricity
Fuel cell
An electrical cell that’s supplied with a fuel and oxygen and uses energy from the reaction between them to generate electricity
Hydrogen-oxygen fuel cell advantages
More efficient
Directly from reaction (no turbines etc)
Aren’t as many stages for heat to be lost
No moving parts so energy isn’t lost from friction
No pollutants
Hydrogen oxygen fuel cell disadvantages
Gas so takes more space to store than liquid fuels
Very explosive so difficult to store safely
Made using electricity that must be generated
Alkenes
- Chains of carbon atoms with double bonds
- Unsaturated
- Decolourise Bromine water by forming bonds with the bromine atoms
- They form polymers by opening their double bonds
Ethene - Propene
Cracking advantages
Turns them into shorter more useful molecules
More demand for shorter molecules
Produce alkenes for plastics
Conditions for cracking
Heat + catalyst
Experiment for cracking
Mineral wool soaked in paraffin
Porcelain chips
Into glass jar
Incomplete combustion
When there isn’t enough oxygen
Carbon monoxide produced
Carbon produced
NOT SAFE
Choosing a good fuel
Ease of ignition
Energy value
Ash and smoke
Storage and transport
Environmental problems with burning fossil fuels
- if incomplete then carbon monoxide and Carbon produced
- Contains sulphur impurities so sulphur dioxide produced which causes acid rain
Acid rain
Caused by sulphur dioxide reacting with clouds to produce dilute sulphuric acid
Kills trees and damages buildings
Causes lakes to become acidic
Sulphur can be removed from fuels before they’re burnt
This takes more energy which takes more fuel which releases more CO2
Acid rain prevention
Acid gas scrubbers to take harmful gases out before they’re released
Cars have catalytic converters to clean up exhaust gases
Reduce use of fossil fuels
Carbon dioxide problems
Greenhouse gas so acts as an insulating layer keeping heat in
Affected by humans- respiration, burning trees, deforestation, fossil fuels
Biofuels
Biogas- microorganisms used to compose living organisms waste
Alcohol- eg ethanol made from sugar
However large amounts of land are needed where we could be growing food
The reactivity series- electrolysis
Purple Sausages Crave Minty Apples
Potassium K Sodium Na Calcium Ca Magnesium Mg Aluminium Al
The reactivity series- carbon
Crazy Zebras Illustrate Tin Ladders
Carbon Zinc Iron Tin Lead
Acid+ Metal carbonate
Salt + water + CO2
Hydrochloric acid + Sodium Carbonate
2HCl + Na2CO3 –> 2NaCl + H20 + CO2
Hydrochloric acid + Calcium Carbonate
2HCl + CaCO3 –> CaCl2 + H2O + CO2
Copper
hard, strong, good conductor
Electrical wires, pipes
Gold
easy to shape, unreactive
Jewellery
