Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chemistry revision Part 4 (Uses and cracking of Crude oil (Cracking is a…
Chemistry revision Part 4
Reversible reactions
Reversible reaction = A reaction where the reactants form products, which react together to give the reactants back. A and B can react to form C and D or, in the reverse reaction, C and D can react to form A and B. This is distinct from reversible process in thermodynamics.
Measuring rates of reactions
The Reaction Rate for a given chemical reaction is the measure of the change in concentration of the reactants or the change in concentration of the products per unit time
Fuel cells
Fuel cell = a cell producing an electric current direct from a chemical reaction.
Much like the batteries that are found under the hoods of automobiles or in flashlights, a fuel cell converts chemical energy to electrical energy.
Cells and batteries
Electricity though chemical reactions. Batteries consist of one or more electrochemical cells that store chemical energy for later conversion to electrical energy. Batteries are composed of at least one electrochemical cell which is used for the storage and generation of electricity.
Atom economy
Atom economy = Is the conversion efficiency of a chemical process in terms of all atoms involved and the desired products produced. Atom economy is an important concept of green chemistry philosophy, and one of the most widely used metrics for measuring the "greenness" of a process or synthesis.
Fractional Distillation
As you go up the fractionating column, the hydrocarbons have:
Lower boiling points
Lower viscosity (they flow more easily)
Higher flammability (they ignite more easily).
Process:
During the fractional distillation of crude oil:
1) Heated crude oil enters a tall fractionating column, which is hot at the bottom and gets cooler towards the top
2) Vapours from the oil rise through the column
3) Vapours condense when they become cool enough
4) Liquids are led out of the column at different heights
Uses and cracking of Crude oil
Cracking is a reaction in which larger saturated hydrocarbon molecules are broken down into smaller, more useful hydrocarbon molecules, some of which are unsaturated:
Catalytic cracking uses a temperature of approximately 550°C and a catalyst known as a zeolite which contains aluminium oxide and silicon oxide
Steam cracking uses a higher temperature of over 800°C and no catalyst
Quantative chemistry
