Abstract
Students find information about the different fractions of crude oil; its use, formulae and write a balanced equation for the reaction with oxygen.
Objectives
Students will be able to:
- Understand crude oil can be separated into useful fractions by a process of fractional distillation.
- Write a balanced equation for the reaction between a hydrocarbon and oxygen.
- Understand the relationship between mole, mass and mole ratio
National Science Education Standard
Content Standard E: The Physical Setting
Energy Transformations
Different energy levels are associated with different configurations of atoms and molecules. Some changes of configuration require an input of energy whereas others release energy.
Strand 5: Physical Science
Concept 4: Chemical Reactions
Investigate relationships between reactants and products in chemical reactions.
PO 6.
PO.10
Explain the energy transfers within chemical reactions using the law of conservation of energy.
Concept 3: Conservation of energy and increase in disorder
PO.6 Distinguish between heat and temperature.
Teacher Background
Crude oil can be separated into useful fractions in a fractionating column. Each fraction boils off at a different temperature. The fractions with increasing numbers of carbon atoms have a higher boiling point. These can be “cracked” to make smaller molecules such as ethane [ethylene]1. Many of these fractions can be used as fuels; reacting with oxygen to form carbon dioxide, water and energy.
Stoichiometry rests upon the law of conservation of mass, the law of definite proportions (i.e., the law of constant composition) and the law of multiple proportions. In general, chemical reactions will combine in definite ratios of chemicals. Since matter cannot be created or destroyed, the amount of each element must be the same throughout the overall reaction. For example, the amount of element X on the reactant side must equal the amount of element X on the product side.
Stoichiometry is often used to balance chemical equations. For example, the two diatomic gases, hydrogen and oxygen, can combine to form liquid, water, in an exothermic reaction, as described by the following equation:
The term stoichiometry is also often used for the molar proportions of elements in stoichiometric compounds. For example, the stoichiometry of hydrogen and oxygen in H2O is 2:1. In stoichiometric compounds, the molar proportions are whole numbers (that is what the law of multiple proportions is about).
Related and Resource Websites
EPA Climate Change http://www.epa.gov/climatechange/index.html
Fossil Fuels http://library.thinkquest.org/17531/fossil.html
Oil & Its Useful Products http://www.wpbschoolhouse.btinternet.co.uk/page04/OilProducts.htm#properties
Stoichiometry Table of Contents http://dbhs.wvusd.k12.ca.us/webdocs/Stoichiometry/Stoichiometry.html
Stoichiometry on Wikipedia http://en.wikipedia.org/wiki/Stoichiometry
International Union of Pure and Applied Chemistry (IUPAC) http://www.iupac.org/dhtml_home.html
Shodor Education Foundation on Stoichiometry http://www.shodor.org/UNChem/basic/stoic/index.html
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