Chemistry 1a-b Flashcards
Why is it important to recycle metal?
Because it only uses a small fraction of the energy needed to mine and extract new metal e.g. recycling copper only takes 15% of the energy needed to mine and extract new copper. Recycling also cuts down the amount of waste in landfill sites
What is the structure of alkanes?
They are made up of chains of carbon atoms, surrounded by hydrogen atoms, different alkanes have different chains of different lengths
What happens if a metal corrodes?
It looses its strength and hardness
What are unsaturated vegetable oils at room temperature?
Liquid
What are the pros of ethanol?
When the fuel is burnt, the CO2 released is absorbed by the plant as it grew-carbon neutral. The only other product is water
Why are hydrogenated oils more useful as spreads for baking cakes and pastries?
Because they have a higher melting point than unsaturated oils so they are more solid at room temperature
What does increasing carbon dioxide cause?
Climate change
What is phytomining?
Growing plants in soil that contains copper. The plant cant use or get rid of the copper so it builds up in the leaves, copper can then be collected in the ash once the plant is burnt in a furnaces
Alternatives to crude oil are available so why do we use so much of it?
Cars are designed for petrol/diesel, its readily available and it is more reliable too e.g. solar and wind power need the right conditions to work
What is the worst case scenario for when oil will run out?
About 25 years
What size can compounds be?
Small molecules like water to big lattices like sodium chloride
Why are properties of compounds different to the original elements?
Because it is a mixture of properties
What are the two ways to chemically extract metal from ores?
Reduction or electrolysis (splitting it with electricity). Some metals have to be concentrated before extraction (to get rid of the unwanted rocky material)
What are group 1 elements?
Metals that react in the same way eg react with water to form an alkaline solution + hydrogen and react with oxygen to form an oxide
What are the disadvantages of this method?
The ethanol isn’t very concentrated so if you want to make it stronger, you have to distill it and purify it
What is the symbol for calcium carbonate?
CaCO3
Atoms join together via chemical bonds to make what?
Compounds
What is an example of covalent bonding?
HCl, a hydrogen atom shares an electron with chlorine
What other substances thermally decompose in the same way?
Magnesium, copper, zinc and sodium carbonate
Why is this not a reliable way to produce ethanol?
Because ethene is made from crude oil which is non renewable and could run out soon, making ethanol from ethene will become very expensive
Positives and negatives of limestone products?
Widely available, cheap, more hard-wearing than marble, looks ok, concrete is very quick and cheap but ugly. Limestone products don’t rot or get eaten by rodents and insects, fire resistant and concrete doesn’t crack, corrode and can be reinforced with steel bars for more strength
What is the formula for Propane?
C3H8
What are the first four alkanes?
Methane, Ethane, Propane and Butane
Where is crude oil used?
Cars, boats, trains, planes, central heating systems and power stations
What are the cons of biodiesel?
We cant make enough to completely replace normal diesel. Its expensive to make and farmers could switch to grow crops for biodiesel, increasing food prices
What do electrons occupy?
Electron shells sometimes called energy levels
Why do we want to crack long chain hydrocarbons?
Because long chain hydrocarbons form thick gloopy liquids like tar which isn’t that useful so a lot of longer chained hydrocarbons, are turned into smaller ones via cracking
What does electrolysis mean?
Splitting up with electricity
How does the profitability of metal extraction change over time?
If the price for the metal drops, extraction isn’t worth it, if it increases then it is worth extracting it. Technology can make it possible to extract more making it easier and possible to extract metal that wasn’t worth it before
What is crude oil formed from?
Buried remains of plants and animals-its a fossil fuel
what are the properties of titanium?
Low density but is very strong and corrosion resistant. Good for replacement hips
Why can’t you do some of these reactions in a school?
Because a bunsen burner can’t reach a high enough temperature to thermally decompose some carbonates of group 1 metals
What other carbonates react with acids?
Magnesium, copper, zinc and sodium
How can poly(ethene) have different properties?
At 200°C and 2000 atmosphere pressure it is flexible and has a low density whereas at 60°C and a few atmosphere pressure with a catalyst it is rigid and dense
What happens when calcium carbonate is heated?
It thermally decomposes to make calcium oxide and carbon dioxide
As well as fuels, what else does crude oil provide?
Raw materials for making various chemicals including plastics
Why is electrolysis more expensive than reduction with carbon?
Because it uses a lot more energy
What does a compound formed from a metal and non metal consist of?
Ions
What does it mean if an alkane has shorter molecules?
The shorter the molecules means it is more runny, less viscous, more volatile (Turn into gas at a lower temperature) lower boiling point and more flammable hydrocarbon
What are similar basic properties of metals?
They are strong but can be bent or hammered into different shapes, they are good at conducting heat and conducting electricity
How does sulfur dioxide cause acid rain?
When it mixes with the clouds it makes dilute sulphuric acid which then falls as acid rain
Why are vegetable oils good in food?
They provide a lot of nergy, they contain lots of nutrients e.g. oils from seeds contain vitamin E and also vegetable oils contain essential fatty acids for metabolic processes
Biodiesel is another new fuel, What is it?
It is another biofuel and can be produced from vegetable oils such as rapeseed oil and soybean oil. Biodiesel can be mixed with ordinary diesel fuel to run a diesel engine
What are two examples of new methods to extract copper?
Bioleaching and phytomining
Why are alloys harder than pure metals?
Because different elements have different sized atoms so when an alloy is made, the layers become irregular and can no longer slide past each other
What are particles of soot and ash doing in the world?
Causing global dimming
What is the formula for Ethane?
C2H6
What metals have to be extracted with electrolysis?
The metals that are higher than carbon in the reactivity series, but electrolysis can be expensive
what is an example of reduction?
Iron oxide becomes iron
You have the same atoms at the start and end of chemical reactions, but what happens to them?
They get arranged in different ways
What are acid gas scrubbers?
They take the harmful gasses out before they are released into the atmosphere
What are the elements in the final group (group 0)
Noble gasses
What sort of fuels are being developed?
Altenative fuels, many are renewable fuels so they won’t run out however there are still pros and cons
What are the first tow alkenes?
Ethene and Propene
Do metal atoms gain or lose electrons?
They lose electrons to form positive atoms
Why are saturated fats less healthy?
They increase the amount of cholesterol in your blood which can block arteries and increase the risk of heart disease
How many electrons can fill the first shell?
2 electrons
What are the cons of ethanol?
Engines have to be converted before ethanol can be used as a fuel and ethanol fuels aren’t widely available. As demand increases, farmers may switch from growing food crops to growing crops to make ethanol which would increase food prices
What does electrolysis require?
A liquid to conduct electricity called the electrolyte
What sort of bonds do unsaturated oils contain?
Double bonds between some of the carbon atoms in their carbon chains, this is why they decolourise bromine waters the double bond opens up, saturated fats have no double bonds
What do elements in the same column have in common?
They have similar properties
How is oil extracted from plant material?
It is crushed and the pressed between two metal plates to squash the oil out, this is the traditional method of producing olive oil
What is cupronickel made out of?
Copper and nickel - hard and corrosive resistant, used to make ‘silver’ coins
What are the benefits of using vegetable oils for cooking?
Higher boiling point than water means foods can be cooked at higher temperatures quicker, it adds a different flavour as oil carries the flavour and stops food sticking to the pan
How is the alcohol in beer and wine made?
By fermentation
What are newly discovered uses for polymers?
Waterproof coatings for fabrics, dental polymers for tooth fillings, polymer hydrogel wound dressings, new biodegradable packaging materials from polymers and cornstarch are being produced
How many bonds do the carbon and hydrogen atoms make?
Hydrogen still only forms one but carbon forms four as it has a double bond
What is an example of polymerisation?
Many single ethenes + pressure and a catalyst = poly(ethene)
Do elements in the same group have the same or different number of electrons in their outer shell?
The same amount of electrons in their outer shell
The atoms form bonds with as many other atoms as they can, what does this tell us about them?
They are saturated
Can you separate two original elements out again from a compound?
It’s usually difficult
What are the properties of aluminium?
It is corrosion resistant and has a low density, pure aluminium isn’t that strong but it forms hard, strong alloys. Good for making aeroplanes
In chemical reactions, what does the mass of reactants equal
The mass of products, e.g. 6g magnesium reacted with 3g oxygen = 10g magnesium oxide
How can acid rain be reduced?
By reducing sulfur emissions
What are electrolytes usually?
Metal salt solutions made from the ore or molten metal oxide. It has free ions which conduct the electricity making the whole thing work
What is metal fatigue?
When a metal becomes too stressed and strained repeatedly over time, leading to the metal breaking. This can be dangerous especially in aeroplanes
WhAT ARE MOST OF THE PRODUCTS OF CRACKING?
Alkanes and unsaturated hydrocarbons call alkenes
How many electrons do noble gasses in their outer shells?
8, except for helium which has two, they are stable and un-reactive
Why do crude oil fraction make good fuel?
Because they burn clearly
Why are the two bonded atoms strongly attracted to each other?
Because they have opposite charges
Hydrogen gas in another new fuel, what is it?
It can be used to power vehicles, the hydrogen comes from the electrolysis of water and there is plenty of water around but it takes up electrical energy which doesn’t come from renewable sources
What are the properties of copper?
Good conductor of electricity so good for electrical wires, hard and strong but can be bent and doesn’t react with water. Good for plumbing
What is this type of bonding called (giving/taking electrons)?
Ionic bonding
Are atoms lost or made in chemical reactions?
Neither, atoms aren’t lost or made in chemical reactions