Friday, November 27, 2009

Representing reactions-IGSCE /GCSE CHEMISTRY NOTES

Word equations
If a reaction occurs between magnesium and oxygen, magnesium oxide is produced, here is the word equation for this reaction: -
magnesium + oxygen --> magnesium oxide
Some other examples are:
hydrochloric acid + calcium carbonate --> calcium chloride+ carbon dioxide+ water
sodium + water --> sodium hydroxide + hydrogen
hydrochloric acid + sodium hydroxide --> sodium chloride + water
Write word equations for the reactions in which the following compounds form from a halogen and another suitable element:
hydrogen fluoride, hydrogen chloride, iron III chloride, iron III bromide, sodium chloride, copper chloride.

The formula of an element or compound is simply the symbol of each element present and numbers to show how many atoms are present. Carbon dioxide has the formula CO2. This means that it has one carbon atom and two oxygen atoms in each molecule.

substance formula substance formula
methane CH4 bromine Br2
ethane C2H6 hydrogen H2
propane C3H8 ethanol C2H5OH

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