Topic: Chemistry
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Mole Ratios in a Chemical Reaction
A balanced chemical equation gives the mole ratios of reactants and products for chemical reactions. If the formulas of all reactants and products are known, it is relatively easy to balance an equation to find out what the mole ratios are. When the formulas of products are not known, experimental measures must be made to determine these ratios.
This experiment uses the method of continuous variations to determine the mole ratios of the two reactants. This method requires several steps. First, solutions of the reactants are prepared in which the concentrations are known. Second, the solutions are mixed a number of times using different ratios of reactants. Third, some property of the reaction that depends on the amount of product formed is measured. This property could be volume of gas evolved, mass of a solid produced, or the amount of heat generated. In this experiment, the reaction is exothermic (produces heat), so the change in temperature of the solution will be measured.
In the method of continuous variations, the total number of moles of reactants is kept constant for the series of measurements. Each measurement is made with a different mole ratio of reactants. The optimum ratio, which is the stoichiometric ratio in the equation should produce the most heat and result in the greatest temperature change.
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