2 Why do the fractions separate? Tick one box. The fractions have different boiling points. The fractions have different viscosity.

Fractions of Petroleum and their uses

Crude oil is separated by fractional distillation. Crude oil is heated to vaporize the different hydrocarbons in a tank which is cool at the top and hot at the bottom. The vapours then rise and the different hydrocarbons condense at their specific boiling points, allowing them to be separated.

Fractional distillation is used to separate crude oil into simpler, more useful mixtures . This method can be used because different hydrocarbons have different boiling points .

Crude oil can be separated by fractional distillation because the molecules in different fractions have different length chains. This means that the forces between the molecules are different. The forces between molecules are called intermolecular forces. These forces are broken during boiling.

Petroleum is a naturally occurring complex mixture made up predominantly of carbon and hydrogen compounds, but also frequently containing significant amounts of nitrogen, sulfur, and oxygen together with smaller amounts of nickel, vanadium, and other elements.

Why do the eight small marble chips react faster than the large marble chip? Tick one box. The eight small marble chips have a larger surface area, so less frequent collisions. The eight small marble chips have a larger surface area, so more frequent collisions.

The most valuable fractions for the chemical industry, and for producing petrol, are liquefied petroleum gas (LPG), naphtha, kerosine and gas oil. These are treated in several ways including cracking, isomerisation and reforming. Figure 1 A view of the steam crackers at Ludwigshafen in Germany.

Some of the smaller hydrocarbons formed by cracking are used as fuels (eg large chains are often cracked to form octane for petrol, which is in high demand), and the alkenes are used to make polymers in the manufacturing of plastics. Sometimes, hydrogen is also produced during cracking.

Cracking, in petroleum refining, the process by which heavy hydrocarbon molecules are broken up into lighter molecules by means of heat and usually pressure and sometimes catalysts. Cracking is the most important process for the commercial production of gasoline and diesel fuel.

Cracking allows large hydrocarbon molecules to be broken down into smaller, more useful hydrocarbon molecules. Fractions containing large hydrocarbon molecules are heated to vaporise them. This helps to meet the demand for the more useful fractions and to increase profit.

Various methods can be used for cracking, eg catalytic cracking and steam cracking: 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 approximately 550°C and no catalyst.

Cracking is important for two main reasons: It helps to match the supply of fractions with the demand for them. The supply is how much of a fraction an oil refinery produces. Since cracking converts larger hydrocarbons into smaller hydrocarbons, the supply of fuels is improved.

Thermal cracking is a process in which hydrocarbons present in crude oil are subject to high heat and temperature to break the molecular bonds and breaking down long-chained, higher-boiling hydrocarbons into shorter-chained, lower-boiling hydrocarbons.

In the absence of air, steam and raw material are mixed and heated to temperatures around 800oC inside a furnace. Carbon dioxide and hydrogen sulfide are unwanted byproducts of thermal cracking. These gases must be removed before they escape into the atmosphere by reaction with sodium hydroxide solution.

Steam cracking These are vaporised and mixed with steam and passed through a reactor heated to about 800 – 900°C. The pressure of the mixture is around 1 atmosphere. The gas flow is very, very fast so that the mixture only remains in the reactor for less than a second.

The decomposition of a compound on heating in absence of air is known as pyrolysis. The breakdown of large organic compounds by use of a catalyst and low temperature to form different smaller compounds is called cracking.

Pyrolysis is the heating of an organic material, such as biomass, in the absence of oxygen. Because no oxygen is present the material does not combust but the chemical compounds (i.e. cellulose, hemicellulose and lignin) that make up that material thermally decompose into combustible gases and charcoal.

Cracking is the coalescence of dispersed globules and separation of the disperse phase as a separate layer. It is an irreversible process and redispersion cannot be achieved by shaking.

store in high temperature leads to decreasing the viscosity of emulsion and cause creaming and get deteriorate, while store in cool or freezed condition leads to formation of ice of dispersion medium leads to cracking of emulsion. (6) Creaming:- Creamy. emulsion are more rapidly cracked than other emulsion.

Creaming is a reversible process, whereas breaking is irreversible. When breaking occurs, simple mixing fails to resus-pend the globules in a stable emulsified form, since the film surrounding the particles has been destroyed and the oil tends to coalesce.