Hydrocarbons are impounds that contain hydrogen and oxygen atoms only a) b) In the exam you may be asked to identify hydrocarbons from their structure. You can see that a) is not a hydrocarbon as it contains oxygen as well Crude oil on its own is not useful but the hydrocarbons it contains on their own are useful and so they need to be separated. They are separated by a process called fractional distillation and this happens in a fractionating column You might have a diagram like the one above and you have to label the fractions in the order they come off the column and so learn them.
You also need to learn what he fractions are used for The fractionating column is heated at the bottom so the bottom is much cooler than the top of the column. The crude oil is piped into the fractionating column and heated. In the exam you could be asked by what property difference are the different hydrocarbons (called fractions) separated by and the answer is Boiling Point Small hydrocarbons have low boiling points so when the crude oil is heated, they travel to the top of the column and leave as a gas (ALP) Hydrocarbons with the highest boiling points stay as a liquid and leave at the bottom of the column (bitumen).
In the exam you could be ask to label where on the column bitumen leaves, and you would put an X on the tube at the bottom of the column) Other fractions turn into a gas at the bottom of the column, they rise up the column and where they cool, turn into a liquid, and are piped off the column Hydrocarbons molecules are held together by intermolecular forces. The larger the hydrocarbon, the more intermolecular forces that are holding the molecules of the hydrocarbon together.
This means a higher temperature is needed to separate the molecules and turn that hydrocarbon into a gas. Drilling for oil Oil was formed millions of years ago from sea creatures and so is trap under layers of impermeable rock (the oil cannot get through). Therefore oil wells drill through the rock to get at the oil. Problems with oil- it is transported in tankers on the sea and sometimes the tankers get damaged and the oil leaks out causes environmental problems The oil ruins beaches and birds get covered in oil and cannot fly.
They cannot feed and die. Detergents are used to try and break the oil up but this also damages wildlife. Political problems that can be caused by crude oil- oil mainly produced by Mounties in the Middle East and consumed by the most by USA and Europe. The Middle East could decide to reduce supplies or put up prices anytime. Cracking Some fractions and more useful and so more in demand than others (e. G. Petrol is more demand than bitumen).
In the exam you could get a bar chart or a table for you to identify which fractions are in more/less demand than others Cracking is a process by which larger, less useful hydrocarbons are cracked into smaller more useful ones to match demand. Cracking involves heating larger oil fractions and passing them over a catalyst Octane examine + ethnocentric CACHE + CHI This means that cracking cracks a large alkaline into a smaller alkaline and an alkaline In the exam you could be asked what cracking is, what conditions are needed and what is produced.
Alternatively you could have the label the diagram below. Burning hydrocarbons Combustion – is the scientific word for when a fuel burns in oxygen (when there is plenty of oxygen available it is called complete combustion). Learn hydrocarbon + oxygen carbon dioxide + water e. G. CHI + 02 CO + AH Experiment to prove that the products of combustion are carbon dioxide and water
Cobalt chloride water is blue and turns pink when water is present, and eliminate turns cloudy when carbon dioxide is present In the exam you could have to label the diagram or describe how you would test for carbon dioxide and water For higher tier, you will be required complete a balanced symbol equation for the complete combustion of a given hydrocarbon CHI + 02 CO + H2O To balance the equation you need to count how many atoms there are of each element of the left side of the equation, and count how many there are on the right side of the equation.
You then put numbers in front to try and balance the equation CHI + 702 CHIC + AH Your teacher will show you how to balance but if you are not confident, you can fill in the symbols in the equation, draw a star next to the equation, and go back to it when you have finished the paper if you have time. The balancing is worth one mark so don’t panic. Sometimes you can do them easily other times you can’t Incomplete combustion This is where a fuel is burnt in insufficient oxygen Learn hydrocarbon + oxygen carbon monoxide + carbon + water Carbon is soot.
Carbon monoxide can be not seen, smelt or tasted and if you breathe it in you die. This is why appliances in the home that burn fuels need to be cleaned often to make sure enough air can get to the fuel. Learn CHI + 202 CO+ C +AH Choosing the right fuel Below is a table with the features of the 3 fuels Factor What this means Coal Fuel Oil Natural gas Availability How easy is it to get hold of? Easy Easy Needs pipes Cost How expensive is it? Low High High Energy value How much energy does it give out when burnt? Tedium High High Pollution Does it contribute to acid rain or the greenhouse effect? High Medium Medium Ease of use How easy is it to use? Difficult Easy Easy Toxicity How poisonous is it? Low Medium Very Low Storage How easy is it to store Easy Easy Difficult You need to be aware of the factors that a fuel is Judged by. You could get a table such of this and suggest a fuel for a given situation and explain why. For example, you could get the table above and have to select a fuel to use to in an oil tanker which transports oil across the sea.
You would select the oil as it is easy to store, easy to use, and readily available. On the negative side, the cost is high Clean air Proportions of gases in present day atmosphere Gas Percentage in air iatrogenic 78% oxygen 21% carbon dioxide 0. 035% others <l% How our present day atmosphere was formed We do not know this theory for sure as no one was around at the time! Earth is 4. 5 billion years old and we think there were loads of volcano around releasing loads of carbon dioxide and water, and some ammonia and methane.
Water condensed and formed the oceans, and carbon dioxide dissolved in the oceans, and this decreased the amount of both in the atmosphere. Some carbon dioxide in the oceans got locked away in Limestone which is a sedimentary rock made up of shells of sea creatures which contained calcium carbonate Plants evolved, took carbon dioxide out of the air and put oxygen into it. Ammonia (NH) was broken down by sunlight to form nitrogen Air pollution The amount of carbon dioxide in the air (0. 035%) should be balanced as respiration by animals and plants, and burning of fossil fuels increases its concentration in the air, and plants remove it by photosynthesis. This is not the case and levels are rising due to deforestation when forests are being cut down for human use (farms, making way for buildings, roads), and with the human population increasing, there is an increase in demand for energy, more fuels are burnt and carbon dioxide levels are rising causing global warming.
Putting carbon dioxide into the atmosphere- respiration by animal and plants (at night), and burning fossil fuels Taking carbon dioxide out of the air- plants take carbon dioxide out of the air during the day for photosynthesis In an exam you could be asked to label the carbon cycle like the one above, or write an extended question on how carbon dioxide is kept in balance in the atmosphere Atmospheric pollutants:- Excess carbon dioxide global warming Carbon monoxide caused by fuels burning in insufficient oxygen sickness and death
Sulfur dioxide (produced when impurities contained in fuels burn in oxygen) acid rain changes the pH of rivers and lakes killing fish, and eroding stonework. Nitrogen oxides also cause acid rain (see sulfur dioxide) and react with other atmospheric pollutants particularly in sunlight and causing photochemical smog (cities look a bit foggy and hazy). This can cause breathing problems Catalytic converts- in car exhausts and reduce damage to human health by converting carbon monoxide produced from car exhausts into carbon dioxide carbon monoxide + nitrogen oxide nitrogen + carbon dioxide ICC +NO NO + CHIC
Alkaline and alleles These are hydrocarbons. They form single bonds and are said to be saturated Alkaline Name Chemical formula Displayed formula Methane CHI Ethane CHI propane CHI Butane SOCIO You might get given the displayed formula (diagram with bonds- looks like sticks) and ask you to write the chemical formula- used count up the number of carbon atoms and write it next to letter C, then count up the number of hydrogen atoms and write next to a letter H. Alternatively you could get asked to draw the displayed formula from the chemical formula.
In alkaline, the carbons are Joined to each other by throng covalent bonds and each carbon forms 4 bonds with other atoms. Hydrogen atoms only form one bond with another atom Alleles ‘Alleles have a double bond in between’, and are said to unsaturated There is no methane Name of alkaline Chemical formula Displayed formula attendance propane CHI betterment Propane could like any of the displayed structure below (count the number of carbon and hydrogen atoms) , , Butane could look different as well, but Just count the number of carbon atoms Test to tell the difference between alkaline and alleles- use bromine water.
The bromine eater is orange and stays orange in alkaline but turn clear when placed in alleles This is an addition reaction and you can add bromine on to the alkaline Polymers Made from alleles which are described as monomers (single units), and many monomers are Joined together to form polymers in a reaction called popularization. High pressure and a catalyst are required in this reaction. You may get asked what popularization is or what conditions are needed For higher you will have to draw the polymer from the given monomer or the monomer from the given polymer Monomer it’s polymer Using polymers
Polymers have different properties and so are used for different things. Below is a table or properties of two different types of polythene (you do not have to learn) LDAP HIDE Density game 0. 92 0. 95 Maximum useable temperature coco 120 strength in Mamma. 8 31. 4 Relative flexibility flexible stiff You could be asked to look at the table above and decide which polymer would be the best for a drinking straw and which for making disposable cups, and why. LOPED for drinking straw and flexible and HIDE for disposable cup as stiff and can withstand high temperatures.
Most plastics have low melting points as there long Haines only have weak inter molecular forces attracting them to each other. They can also be easily stretched which is useful in plastic carrier bags for shopping. In some polymers the polymers chains are cross-linked and so the plastic is rigid and cannot be stretched Cortex is a polymer that is used for waterproof clothing It is tough, waterproof, but breathable. It stops rain getting in but lets sweat out. One layer is made from polyurethane or a polymer PETE, which has holes too small to let rain in but large enough to let water vapor (sweat) out. PETE is laminated as it is regale.
Polymer problems- polymers are enervative (which is why we use them for storing things etc) but they are non-biodegradable (are not rotted away by bacteria). Plastic gets buried in the ground in a landfill site (85% of UK rubbish ends up in landfill). We are running out of places to bury rubbish and they are not easy to site as they smell and attract rats and gulls. Crude oil is the raw material for most polymers. These can be burnt to get rid of but it has to be at high temperatures to stop toxic gases. The heat generated by burning could be used to heat buildings or enervate electricity but if it isn’t it is a waste.
Some polymers can be recycled to make fibers for clothing. However, recyclable plastic are mixed with others that cannot be recycled, and the sorting is time consuming and expensive. We now have polymers which are biodegradable e. G. Starch is added to polymers during manufacture. When the polymer gets wet bacteria break down the starch and the polymer crumbles. Chemical changes Cooking involves chemical changes as a new substance is made, it is irreversible, and energy changes happen. Cooking changes the appearance, texture and taste of odds.
Eggs and meat contain proteins and when cooked the protein molecules change shape (denatured). This is an irreversible process. Potato contains a lot of starch, tastes bitter when the potato is uncooked, and it is difficult to digest. When you cook potato, the cell walls break down, making the potato softer. Also, the starch grains inside the potato cells swell and are released from the cell and this makes the potato easier to digest. Baking powder- Contains sodium hydrogen carbonate which when heated breaks down (thermal decomposition) to release carbon dioxide which helps cakes rise.
You can test for carbon dioxide gas by bubbling it through eliminate which goes from clear to cloudy Sodium hydrogenation’s sodium carbonate + carbon dioxide + water nacho Niacin + CO + H2O Food additives Type of additive Reason for adding it Example Antioxidant Stops food reacting with oxygen and going off Vitamin C Food color Gives food an improved color to make it more attractive caramel Flavor enhancer Improves the flavor Monogamous glutamate Emulsifier Stops oil and water in the food from separating Egg yolk lecithin Emulsifiers- these stop water and oil separating.
Egg yolk containing lecithin in added to mayonnaise to stop the oil and the vinegar separating. Emulsifiers have a hydrophilic end (water-loving) which goes into the water/vinegar, and a hydrophobic end (water-hating end) which goes into the oil. You could get an extended question asking you what additives are added to food send what they do. You could get asked how emulsifiers work. You might have to label the ends of an emulsifier. Cosmetics- Some cosmetic ingredients are natural e. G. Glycerin but others contain artificial or synthetic substances.
Perfumes- improve the smell of products and they need certain repertories Desirable physical property Reason the perfume needs this property Evaporates easily Perfume particles must reach the nose Non-toxic (non-poisonous) Must not poison the user Does not react with water Must not react with sweat on the skin Does not irritate the skin Should not hurt the skin when applied Insoluble in water (does not dissolve in water) Should not be washed off easily Perfumes can be from natural sources e. G. Owes, lavender, sandalwood Volatility- a measure of how easily a liquid turns into a gas. Molecules in a liquid are attracted to each other and heat overcomes the forces ND separates them turning the substance into a gas. Perfumes evaporate easily as the attractions between the particles are so weak that skin heat is enough to overcome them and turn the perfume into a gas (for us to smell). Esters- esters are compounds that smell nice and they are made by reacting alcohol with acid (with a bit of concentrated sulfuric acid acting as a catalyst) alcohol + acid ester + water e. G. Ethanol + ethnic acid ethyl ethanol + water words ending in ‘OLL’= alcohol words saying acid = acid words ending in ‘annotate’ = ester In an exam you may get a word equation like the one above with reactant and/ reduce names missing Solutions- mixture of solute (solid part) and solute (liquid part). For example salt water (solution) is a mixture of salt (solute) and water (solvent). Some solutes do not dissolve in the solvent water (you cannot take your nail varnish off with water), and they are said to be insoluble. Nail varnish will dissolve in the ester ethyl ethanol and is said to be soluble in it.
Whether a substance dissolves in a solvent depends on the relative strength of the attraction between:- The particles of the substance and the solvent The particles of the substance itself The solvent molecules So, nail varnish will not dissolve in water are the strength of the attractions between the nail varnish particles themselves is greater than between the nail varnish particles and the water molecules. Testing cosmetics- Cosmetics need to be tested so that they do not harm us. In some countries they are tested on animals.
In Europe this was banned in 2009, and cosmetics can only include ingredients that had previously been tested on animals or human volunteers. In I-J, cosmetics can be tested on animals if they have a medicinal value e. G. Creams for skin complaints. For testing on animals- makes sure medicines are safe. Against testing on animals- morally wrong, expensive to keep the animals. Paints and pigments- Pigment – colored substance used in dyes and paints (plants, rocks and animals provide natural pigments, modern pigments are brighter, last longer and have been made by chemists).
Paints- To to decorate or protect surfaces and are made up of 3 things:- Ingredient Function Pigment Gives color Binding medium Sticks the pigment to the surface being painted Solvent Thins the paint to it spreads easily As paint dries the solvent evaporates leaving the pigment attached to the wall. Emulsion paint- has water as the solvent Oil paint- oil is the solvent Oil paints are used to decorate doors and window frames and leave a tough shiny layer.
The solvent oil is hydrocarbon oil and as it evaporates it also reacts with oxygen in the air which makes the paint layer tough. Colloids- this is a type of mixture where on substances is spread out evenly in a solvent but are not dissolved. Paints are colloids as the pigment is evenly spread out in the solvent but is not dissolved. Smart paints- Thermometric pigments- pigments which change color in different temperatures. Used in strip thermometers which go on the forehead and measure if you have a ever, and mood rings, mugs to show contents are hot.
Thermometric paints can be mixed with acrylic paints to give even more color changes Phosphorescent pigments- In the light these pigments absorb energy, and they release the energy slowly over time and can be seen in the dark (will stop when all the energy is released). Radioactive substances can be used to make glow-in-the- dark paints e. G. Radium is used. If radium is mixed with phosphors, the radiation makes the phosphors glow brightly. Tritium is another radioactive pigment. Radiation can cause cancer although modern phosphorescent pigments are safer.