C3- Chemical Economics

• An EXOTHERMIC reaction is when it GIVES OUT ENERGY to the surroundings, usually in the form of heat which is shown by a RISE IN TEMPERATURE
• An ENDOTHERMIC reaction is when it TAKES IN ENERGY from the surroundings, usually in the form of heat which is shown by a FALL IN TEMPERATURE

You can measure the amount of energy released by a chemical reaction by taking the temperature of the reactants, mixing them in a polystyrene cup and measuring the temperature of the solution at the end of a reaction. Adding an acid to an alkali is an exothermic reaction so measure the temp of the alkali before you add the acid and measure temp again you will see an increase. Adding ammonium nitrate in water is endothermic so adding 2 spatulas of this to a polystyrene cup will be a fall in temperature

• Bond breaking is endothermic as energy is supplied
• Bond forming is exothermic as the energy released is greater than the energy used in breaking old bonds

Energy Transferred= Mass of Water x Specific Heat Capacity of Water x Temperature Change

You find the mass of fuel burned by subtracting the final mass of the fuel and burner from the initial mass

Fair Test

• To compare the energy content of different fuels you need to do the same experiment several times
• Everything (except the fuel) should be the same
• Same apparatus
• Same amount of water
• Start and finish at the same temp each time

• A slow reaction is the rusting of iron or chemical weathering, moderate speed reaction is a metal reacting with a dilute acid, a fast reaction is burning or an explosion
• The rate of a reaction that produces a gas can be observed by measuring how quickly the gas is produced: measure the change in mass as the mass will fall, measure the volume of gas given off by using a gas syringe to measure the volume of gas

The rate of a chemical reaction depends on:

• Collision theory
• Energy transfered

More reactant used means more product is formed.........

• More reactant means more particles which have more reactions which cause more products
• The amount of product you get is directly proportional to the reactant that is totally used up

Increasing the temperature means the particles will move quicker because they have more kinetic energy, if they are moving quicker then they will have more collisions. It increases the energy of the collisions since they are moving faster

Increasing the concentration or pressure means the particles are more crowded together. It means there are more particles of a reactant in the same volume which makes collisions more likely. In a gas increasing the pressure means they are more crowed so the frequency increases

Larger surface area by breaking it up into chunks means the particles have more area to work on so the frequency increases. Fine powders and combustible dispersed in the air burn fast because they have a big surface area. If there is a spart they will ecplode which is why factories who make custard powder or powdered sulfur have to be careful

A catalyst increases the speed of a reaction which works by giving particles to stick to where they can bump into eachother and it reduces the energy needed by the particles before they react. The overall number of collisions is increased but the number of successful collisions is

The relative atomic mass is the bigger number!!! Carbon is 12 and Oxygen 16!!!!!

• In a chemical reaction, no atoms are destroyed and no atoms are created
• This means there are the same number and types of atoms on each side of the reaction equation
• Because of this no mass is lost or gained- the mass is conserved during a reaction
• By adding up the relative formula masses on each side you can see the mass is conserved
• You can use simple ratios to calculate the reacting masses in a reaction

1) Write out the balanced equation

2) Work out the Mr

3) Divide the reactant by the reactant to get 1g and then multiply the 1g by the thing in the question to get the answer

Alot of reactions make more than one product, some will be useful but others will be waste products. The atom economy of a reaction tells us how much of the mass of the reactants is wasted when manufacturing a chemical

Atom Economy= total Mr of desired products

                              total Mr of all products

100% atom econom means that all the atoms in the reactants have been turned into useful products, the higher the atom economy the 'greener' the process

• Reactions with low atom economies use resources up very quickly and their waste products have to be disposed of somehow which makes the unsustainable
• Low atom economies aren't often profitable
• The best thing to do is find a use for the wasted materials
• Reactions with the best atom economy only make one product

The more reactants you start with the higher the yield will be, the predicted yield of a reaction can be calculated

percentage yield= actual yield (grams)

                            predicted yeild (grams)

Industry want a high percentage yield to reduce waste and costs

Percentage Yield will be reduced through

• evaporation
• not all reactants react to make a product
• filtration: you can use a bit of a liquid or a bit of a solid
• transferring liquid: you lose a bit transferring it from one container to another as it gets left on the surface

Batch Production: Pharmaceutical drugs are difficult to make and there is low demand for them, batch production is cost effective because it is flexible, start up costs are relatively low but it is labour-intensive and it is difficult to keep the quality the same from batch to batch

Continuos Manufacture: Is used for popular processes like the Haber Process or making ammonia because production never stop, it runs automatically, the quality of the product is very consistent but the start-up costs to build the plant are huge and it isn't cost-effective to run at less than full capacity

Pharmaceutical Drugs cost alot

• Research and development
• Trialling
• Manufacture

Pure substances wob't be seperated by chromatography and they have a specific melting and boiling point, if it is impure the melting point will be too low and the boiling point will be too high

• Diamonds are lustruos and sparkly ideal for jewellery. Each carbon atom forms four covalent bonds in a very rigid structure which makes the diamond really hard. This makes them ideal as cutting tools. The strong covalent bonds take alot of energy to break and have a high melting point and it doesn't conduct electricity because it has no free electrons or ions
• Graphite is opaque and each carbon atom has 3 covalent bonds which create sheets of carbon atoms. The layers are held together weakly so they are slippery and can be rubbed off onto paper. Graphite is a good lubricating material, it also has a hgh melting point and can conduct electricity as there are delocalised electrons
• Diamonds and Graphite are giant molecular structures because carbon can form lots of covalent bonds with itslef. Because of all the bonds the structures are strong and because of the high melting points they don't dissolve in water and don't conduct electricity because there aren't any free electrons or ions
• Fullerenes are molecules of carbon and can be used to cage other molecules and can trap inside. They can be used to deliver a drug. Fullerenes can be joined together to form nanotubes which have a huge surface area so they are used as industrial catalysts