HMB203H1 Chapter 4: Chemistry Chapter Four.doc

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5 Jun 2012
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A chemical reaction is a process in which one set of substances (reactants) is converted to a new set of substances (products). The main evidences that prove that a chemical reaction has occurred are: colour change, formation of a solid (precipitate) within a clear solution, evolution of a gas, evolution or absorption of heat. To write the shorthand representation of a chemical equation certain steps must be followed. Consider the chemical reaction: nitrogen monoxide + oxygen nitrogen dioxide: write the reaction using chemical symbols. No + o2 no2: balance the chemical equation. Remember these rules when balancing an equation: an equation can be balanced only by adjusting the coefficients of formulas, never introduce extraneous atoms to balance. No + o2 no2 + o: never change a formula for the purpose of balancing an equation. When balancing equations, using these strategies will result in efficient balancing of chemical equations. Balance elements that occur in only one compound of each side first.