Chemistry- Core Flashcards
The benefits and costs of emulsion
\+looks nice \+low in fat \+good texture \+thicker - allergies, uses egg yolks
How do emulsions work?
Hydrophilic latches on to water molecules
Hydrophobic latches on to oil molecules
Other oil droplets are repelled by the hydrophilic part while the water molecules latch on so the emulsion does not spread out
Describe an ionic bond
Its between metal and non-metal atoms
Metal loses one electron and forms a positive ion whereas the non-metal gains electrons and forms a negative ion
What are the negative effects of quarrying?
Ruins landscape Noise pollution Burns fossil fuels Dust effects breathing Air pollution from trucks
What are the positive effects of quarrying?
Its used to make houses and roads Restores land once finished Boosts local economy Neutralises acidic soil and rivers Neutralises sulfur dioxide
What is hydrogenation?
The process of hardening vegetable oils to increase there boiling temperatures
Describe the process of hydrogenation
Reacting vegetable oils with hydrogen over a nickel catalyst at 60degrees
How is ethanol used as an alternative fuel and what are the pros and cons?
-fermentation of plants
+ carbon neutral
- engine has to be converted
-have to grow instead of food raising food prices
Where is hydrogen from (alternative fuel) and what are the pros and cons?
-water and electrolysis
+ clean
-expensive
-hard to store
What is polymerisation? What alter the polymers properties?
Polymerisation is when the double bonds in alkenes open to form single bonds thus joining molecules together
- what its made from, the temperature and the pressure during polymerisation
Why are vegetable oils used in cooking?
Provide energy Contain nutrients such as vitamin E Contain essential fatty acids Higher boiling points so can cook quicker at higher temperatures Different flavours
How does the test for carbon dioxide work?
Limewater is a solution of calcium hydroxide and is alkaline so when it reacts with carbon dioxide which is a weak acid it forms tiny solid particles of insoluble calcium carbonate (precipitate) this proves that there is carbon dioxide in the solution
What happens when an element from group 1 reacts with water?
An metal hydroxide and hydrogen are formed
How is ethanol produced from sugar?
Sugar=ethanol+carbon dioxide (yeast) The enzymes in the yeast break down the sugar to form ethanol and carbon dioxide this is called fermentation \+sugar is renewable \+cheap \+low temperatures -not highly concentrated - has to be distilled and purified
How is ethanol produced from ethene?
The ethene is passed over a catalyst with steam this is called hydration \+cheap \+reversible and continuous \+no waste - ethene is produced from crude oil -high energy and pressure
Name environmental problems
Carbon monoxide - incomplete combustion red blood cells pick it uk and carry it to cells instead of oxygen it is poisonous
Nitrogen oxides - high temps acid rain
Sulfur dioxide- acid rain damages buildings, limestone statues and makes lakes acidic
Carbon dioxide - pollution
What is cracking?
The process of splitting up longer chain molecules into smaller more useful molecules
How does cracking work?
The long chained molecules are vaporised and passed over powdered aluminium oxide (catalyst) at 400-700 degrees the molecules split on the surface of the catalyst
This is a THERMAL DECOMPOSITION reaction
Which hydrocarbon is saturated, alkenes or alkanes?
Alkanes
Why doesn’t methene exist
Methane only has one carbon atom so couldn’t be double bonded
How do you make cement?
Powdered limestone is heated in a kiln with powdered clay
How do you make mortar?
Cement +sand + water = mortar
How do you make concrete?
Cement + sand + aggregate
Why would decane have a have a higher boiling point that propane?
Long chain hydrocarbons have more bonds which take more energy to break apart so long chain hydrocarbons have higher boiling points
Why isn’t pure iron useful?
Regular arrangement of atoms which have layers that easily slide over one another this makes it too soft and too bendy
Why is cast iron difficult to use?
Its 4% carbon so is brittle and hard as well as difficult to be compressed
- it can be moulded when molten
What is low carbon steel used for?
Easily shaped
Car bodies
What is high carbon steel used for?
Hard
Inflexible
Blades and tools
What is stainless steel used for?
Corrosion resistant
Cutlery
How do you convert cast iron to steel?
- Put it in a blast furnace
- Blow oxygen into the furnace
- This reacts with molten iron
- Produces carbon dioxide can carbon monoxide and steel
What is a metal ore?
A rock that has enough metal in it to make it economically worth extracting
What is reduction?
Reduction is the removal of a metal from an ore by using carbon as long as the metal is below carbon in the reactivity series
What is smelting?
Heating a metal ore in order to extract its metal
Why do you have to use electrolysis to purify copper after it has been smelted?
The copper does not conduct electricity after it has been smelted as its impure
How does electrolysis work?
- The electrons go from the metal atoms to the anode (positive electrode) and turn to postively charged ions
- Ions then go to the cathode (negative electrode) and turn back to metal atoms
- The impurities are dropped at the anode as sludge
How does bio-leaching work?
Uses bacteria to separate the copper from the copper sulfide
Bacteria gets energy from the bind separating out the copper from the ore
Leachate is the product which contains copper which has to be filtered out
What are the impact of extracting metals?
- noise
- mining shafts are dangerous
- pollution
- scares landscape
+ jobs
+ local economy
+ useful products made
How does displacement work?
Put a more reactive metal with another metal and it will displace this is because the metal bonds more strongly to the non-metal pushing it out
How does phytomining work?
Plants are grown in soil which contains copper
Plants take copper in but cant use it so they store it in the leaves
Plants are harvested, dried, burned
Copper is then collected from the ash
Name the properties of copper
Conductor of electricity
Doesn’t react with water
Hard
Strong
Name the properties of aluminium?
Corrosion resistant
Low density
Not strong
Forms strong hard alloys
Name the properties of titanium
Corrosion resistant
Low density
Very strong
How do you extract aluminium?
Electrolysis - molten aluminium oxide at high temperatures
How do you extract titanium?
Displacement - with sodium or magnesium
Have to convert to chloride
Then distill and purify
Why would you not use carbon to displace and extract titanium?
Reacts with the titanium making it brittle
What was Wenger’s theory?
All continents came from a massive continent called Pangea
They all fit like jigsaw pieces
Matching layers and rocks
Similar fossils that were in the wrong areas
Describe the earth structure
Crust: 5-50km very thin made up of tectonic plates
Mantle: starts at core 3000km down acts like a solid but is very hot
Core: radius of 3500km nickel and iron
Outer: liquid
Inner: solid
How are mountains and volcanos formed?
The tectonic plates collide pushing each other up
How did the early atmosphere evolve?
- earth cooled and thin layer of crust formed
- volcanoes erupted water vapour, ammonia, methane and lots of co2
- water vapour condensed into oceans
- plants and algae liked co2 so grew all over earth
- took in co2 and produced O2 using photosynthesis
- CO2 dissolved into ocean and locked up in sedimentary rocks
- O2 build up, killed early organisms
- created ozone layer blocked harmful sun rays and allowed complex organisms to form
Can we predict earthquakes and volcanic eruptions?
No, but there are usually signs such as ground bulges and mini earthquakes near the volcano
Earthquakes rocks get hotter
How does fractional distill air work?
Air is filtered
Cooled to -200 degrees and becomes a liquid
Water vapour condenses and is removed
Liquid enters column and is heated slowly
Separated air
CO2 and argon come out together so go to another column
What is the primordial soup theory?
Earth was rich with nitrogen, hydrogen, ammonia and methane, lightening struck and caused a chemical reaction between the gases forming amino acids which were collected in a body of water, these combined to form organic matter and living organisms
What are the advantages if using limestone as a building material?
Widely available, cheap, concrete can be poured into moulds, fire resistant, don’t rot
What is a biofuel and give an example?
Biofuels are fuels made from plant and animal matter
E.g. Ethanol
Describe a covalent bond
Two or more non-metal atoms each atom shares an electron with the other
The total masse before …
Equal the total mass after
When the non-metals react with metals what are the particles called?
Ions
When the non-metals react with the non-metals what are the particles called?
Molecules
What are groups?
Elements with similar properties
Give the properties of an ionic bond
Strong due to opposing charges
What is the atomic number?
The number of protons
How do you work out the number of neutrons?
Mass number - atomic number
Why is there no overall charge on an atom?
Equal amount of protons and electrons so they cancel each other out
Neutrons are neutral
Protons are positive
Electrons are negative
Name the good properties of limestone
Cheap, hardwearing, doesn’t rot or corrode
Describe how a rotary kiln works?
Fill with crushed limestone Heat using hot air CaO comes out bottom Waste gas leaves top Rotated so limestone is mixed well
Give limestone cycle equations
CaCO3 > CaO + CO2
CaO + H2O > Ca(OH)2
Ca(OH)2 + CO2 > CaCO3 + H2O
What was wrong with the miler-Urey experiment?
- only 11 amino acids
- not correct ones
- not as many made
- no proof of lightening
Give formula for alkane
CnH2n+2
Give formula for alkene
CnH2n
What happens to bromine when it reacts with an unsaturated hydrocarbon?
Reacts and goes colourless
What happens when bromine water react with a saturated hydrocarbon?
No reaction and it stays orange
Describe fractional distillation
- Crude oil goes through pipe as vapour
- Hot at bottom and cool at top
- Oil remains as a liquid this goes out the bottom
- Vaporised oil rises up the column and at various fractions condense when they reach there boiling points
- There collected at the different points
What is the product of cracking?
Alkanes and alkenes
How do you reduce SO2
Stop burning fossil fuels
Acid gas scrubber
Catalytic converter
Why do some oils need to be distilled after extraction?
To remove water
Solvents
Impurities
What does cracking do?
Open double bonds and increase melting points
