Category Archives: Chemical Concept

Cracking of Oil

Introduction

Fuels made from oil mixtures containing large hydrocarbon molecules are inefficient. They do not flow easily and are difficult to ignite. Crude oil often contains too many large hydrocarbon molecules and are not enough small hydrocarbon molecules to meet demand.

Fractions that are produced by the distillation of crude oil can go through a process called cracking. This chemical reaction produces smaller hydrocarbons, including alkanes and alkenes.

There are a several types of cracking – Thermal Cracking, Catalytic Cracking, Hydrocracking etc.

Explanation

 

 

References

Cleveland, C. (2013). Cracking. Retrieved March 22 from, http://www.eoearth.org/view/article/151525/

Freudenrich,C. (2001). How Oil Refining Works. Retrieved March 22 from, http://science.howstuffworks.com/environmental/energy/oil-refining5.htm

Polymers and ethanol from oil. (n.d.). Retrieved March 22, from http://www.bbc.co.uk/schools/gcsebitesize/science/aqa_pre_2011/oils/polymersrev2.shtml

Fractional Distillation of Crude Oil

Introduction

Fractional distillation consist of a tall column is fitted above the mixture, with several condensers coming off at different heights. The column is hot at the bottom and cool at the top. Substances with high boiling points condense at the bottom and substances with low boiling points condense at the top. Crude oil is made up of different substances with different boiling points hence, these substances can be separated by fractional distillation.

Explanation

The steps of fractional distillation:

  1. Heat the mixture of crude oil to a high temperature. (High pressure steam + 600 degrees Celsius)
  2. The mixture boils, forming vapor (gases); most substances go into the vapor phase.
  3. The vapor enters the bottom of a long column that is filled with trays. The trays have many holes in them to allow the vapor to pass through. They increase the contact time between the vapor and the liquids in the column and help to collect liquids that form at various heights in the column. There is a temperature difference across the column (hot at the bottom, cool at the top).
  4. The vapor rises in the column.
  5. As the vapor rises through the trays in the column, it cools.
  6. When a substance in the vapor reaches a height where the temperature of the column is equal to that substance’s boiling point, it will condense to form a liquid.
  7. The trays collect the various liquid fractions.
  8. The collected liquid fractions may pass to condensers, which cool them further.

References

Fuels from crude oil. (n.d.). Retrieved March 22, from http://www.bbc.co.uk/schools/gcsebitesize/science/aqa_pre_2011/rocks/fuelsrev3.shtml

Freudenrich, C. (n.d.). Retrieved March 22, from http://science.howstuffworks.com/environmental/energy/oil-refining4.htm

The Basic Products From Fractional Distillation. (n.d.). Retrieved March 22, from http://www.spesttmigas.org/2014/07/the-basic-products-from-fractional.html

Formation of Crude Oil

Introduction

Crude oil, commonly known as petroleum is a liquid found in Earth’s crust and is made up of hydrocarbons, organic compounds and small amounts of metal.

Explanation

Dead animals and plants in the sea drop to bottom of sea bed and build up on the sea bed

There is a mud layer and dead animal layer on top of the sea bed. The mud layer gradually turns to rock

The mud layer turns into rock layer and dead animal and plant layer turns into crude oil

The remains of animals and plants in the sea were buried under sand and rocks where decomposition will occur. During  decomposition, certain chemicals such as phosphorus, nitrogen and oxygen will be removed by tiny bacteria. This leaves behind the remains that are mainly made up of carbon and hydrogen. At the bottom of the ocean there is insufficient oxygen for the remains to decompose entirely. Hence, what we are left with is the raw materials for the formation of petroleum.  In addition, over millions of years, the heat and pressure, without air, convert the remains to oil. In this process, gas is also produced.

At an oil rig, production wells cut through to oil layer in the sea bed and draws oil to the surface

Today, oil companies drill down deep into the sea bed through the impermeable rock to obtain crude oil through the process of fractional distillation.

References

How crude oil was formed. (n.d.). Retrieved March 22, from http://www.bbc.co.uk/bitesize/standard/chemistry/materialsfromoil/how_crude_oil_was_formed/revision/2/

Petroleum formation. (n.d.). Retrieved March 22, from http://www.petroleum.co.uk/formation

Making crude oil useful. (n.d.). Retrieved March 22, http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway_pre_2011/carbon_chem/4_crude_oil1.shtml

Chemical Concepts (Unit 4)

Introduction:
This course allows one to have a rough idea on the implications of chemistry on the society through illustrating on the various interaction man has with chemistry. This better allow us to relate to chemistry in our daily life.

Explanation:

Lewis structures and shapes

  • Lewis structures,” which combine multiple atoms using electron dot diagrams, and show bonding electrons as well as lone pairs of electrons. It’s very important to know how to draw both electron dot symbols and diagrams, as well as Lewis structures, because you can get a lot of relevant information from these structures, including electron location, number and types of bonds, and geometric structure.

Valence Shell Electron Pair Repulsion Theory

  • This theory assumes that each atom in a molecule will achieve a geometry that minimizes the repulsion between electrons in the valence shell of that atom.

IR Spectrum and interaction with molecule

  • Infrared Spectroscopy is the analysis of infrared light interacting with a molecule. This can be analyzed in three ways by measuring absorption, emission and reflection. The main use of this technique is in organic and inorganic chemistry. It is used by chemists to determine functional groups in molecules. IR Spectroscopy measures the vibrations of atoms, and based on this it is possible to determine the functional groups. Generally, stronger bonds and light atoms will vibrate at a high stretching frequency (wave number).

3 laws of thermodynamics

Uses of energy

  • We divide our energy use among four economic sectors: residential, commercial, transportation, and industrial. Heating and cooling our homes, lighting office buildings, driving cars and moving freight, and manufacturing the products we rely on in our daily lives are all functions that require energy. If projections are correct, we’re going to keep needing more. Global consumption is expected to increase by 44% over the next 2 decades.

References:

  1. Chemistry in society. (n.d.). Retrieved February 16, 2015, from http://www.educationscotland.gov.uk/highersciences/chemistry/chemistryinsociety/index.asp
  2. Mulleague, M., Rupawalla, M., Singh, H., Johl, R., & Reid, K. (n.d.). Infrared Spectroscopy. Retrieved March 12, 2015, from http://chemwiki.ucdavis.edu/Physical_Chemistry/Spectroscopy/Vibrational_Spectroscopy/Infrared_Spectroscopy
  3. Electron Dot Diagrams, Lewis Dot Symbols, and Lewis Structures. (n.d.). Retrieved March 12, 2015, from http://www.wyzant.com/resources/lessons/science/chemistry/lewis_structures_vsepr
  4. Boundless. “The Three Laws of Thermodynamics.” Boundless Chemistry. Boundless,(n.d.).  01 Dec. 2014. Retrieved 12 Mar. 2015 from https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/thermodynamics-17/the-laws-of-
  5. Valence-Shell Electron-Pair Repulsion Theory (VSEPR). (n.d.). Retrieved March 12, 2015, from http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch8/vsepr.html
  6. The National Academies. (n.d.). Retrieved March 12, 2015, from http://needtoknow.nas.edu/energy/energy-use/