Balancing Equations/Carbon compounds
Number of atoms in reactants = Number of atoms in products
(aq) dissolved in water (aqueous solution)
Caron is a element found in group 4 of the periodic table. This means there are 4 electrons on the outer shell.
This means that carbon atoms can bond together to make chains of ulimited size. Som bonds on the carbon atoms remain free to join with other atoms to form carbon compounds.
Organic chemisrty / Alkanes
Organic compounds contain carbon and hydrogen and are the basis of all life. They are found in all living things. The study of this is called organic chemistry.
An alkane i a SATURATED HYDROCARBON
A hydrocarbon is an organic compound containing hydrogen and carbon only. The 'spine' of a hydrocarbon is made up of a chain of carbon atoms. When more than one carbon atom is present, they are joined by single covalent carbon-carbon bonds.
A covalent bond is a very strong bond formed when electrons are shared between non-metals. We can say that the carbon bonds are saturated because each carbon atom is bonded to the maximum number of atoms. THIS IS KNOWN AS AN ALKANE.
The next three simplest alkanes are- ethane, propane and butane. They are fairly unreactive but do burn well
The alkenes are another type of hydrocarbon.
They are very similar to the alkanes, except that they are joined by a double covalent carbon-carbon bond. Because they are not bonded to the maximum number of atoms we call them unsaturated hydrocarbons.
A simple test to distingush between alkanes and alkenes is to add bromine water. Alkenes will decolourise bromine water as the alkene reacts with it. Alkanes have no effect on it.
Ethene can be reacted with water in the presence of catalyst to produce ethanol.
Cracking the breaking down of a long-chain hydrocarbon molecules into more useful short-chain hydrocarbon molecules, which release energy more quickly when burned.
The long-chain hydrocarbon is heated until it vaporises.
The vapour is then passesover a heated catalyst where a thermal decomposition reaction takes place.
When alkanes are cracked both alkanes and alkenes are formed.
Monomers to Polymers.
Polymers are long-chain molecules.
They are formed from unsaturated monomers.
A monomer is a short-chain hydrocarbon molecule.
Monomers join together to form long-chain hydrocarbon molecules (polymers)
Because alkenes are unsaturates, they are very good at joining together.
Addition polymerisation- is when alkenes join together without producing another substance.
Properties of Polymers.
They have good strength and elasticity
They do not corrode
They are good electrical and thermal insulators
They have low densities
They can be made into any colour
They can easilt be moulded into any shape
Thermosplastics can easily be softened and remoulded into new shapes.
Their polymer chains are held together in their structure by weak intermolecular forces which also give the material some stregth.
However, these forces can easily be over come by applying heat, which softens the polymer and enambles it to be reformed as the chain slip easily over each other. It is not very rigid becuase there are fewer remaining forces.
Can be softened and moulded into a new shape the first time they are heated. (theycant be resoftened and reshaped)
The starting materials first react together when they are heated to form a thermosetting polymer, and they release water molecules. This is a condensation reaction.
The molecules in the resulting thermosetting polymer are crosslinked, making the polymer rigid and strong, and unable to be reshaped when reheated
Changing properties/disposing of plastics
Plasticisers- are added to make thermoplastics more flexible. The plasticiser molecules fill the gaps between the chains, allowing them to slip over each other more easily.
UV (ultraviolet) and thermal stabilisers- are added to prolong a plastics life.
Crosslinking agents- encourage the molecules to form cross links. This increases high temperature performance (melting point) and gives a more stable plastic.
Burning plastics- produces air pollution.
Landfill sites- most plastics are non-biodegradable- they will not decompose and rot away meaning plastics will build up.
Shorter chain hydocarbons are better fuels because when they are burned they release energy more easily.
To keep up with demand and increase relative amounts - longer-chain hydrocarbons are broken down in shorter-chain hydrocarbons by cracking.
These compounds are used to fuel transport, heat homes, make substance for drugs, food, cosmetics, cleaning products, plastics for clothing, bags, electrical equipment etc...
Vegtable oils- are used in cooking and are unsaturated. They are liquids at room temperature because they high levels of monounsaturated and polynsaturated fats.
monounsaturated- have have only 1 double carbon-carbon bond BUT polyunsaturated have 2 or more.
Relative Formula Mass
The development of new medication is a lengthy and expensive process.
The relative formula mass of a compound is the sum of all its elements added together. To calculate it we need to know the formula of the compound, and the relative atomic mass, of all the atoms involved.
...is a meaure of the amounts of reactants that end up as useful products.
Calculating atom economy-
Atom economy = ( mass of (atoms in) useful product / Total mass (of atoms) of product ) x 100 %
expected yield- is the amound of product expected from a reaction
Theoretical yield- calculated from the masses of the atoms
Actual yield- the actual mass obtained from the reaction in the experiment
Percentage yield = (Actual yield/Maximum theoretical yield) x 100 %
- Addition- when molecules react together to produce a larger molecue with no other product.
- Empirical- the simplest ratio of atoms in a compound as reperesented by the chemical formula.
- Hydrogenate- to add hydrogen to an unsaturated compound
- Synthesis- the formation of a compound from its constituent elements