To determine the effect of altering concentration (mol dm-3) of hydrochloric acid (HCl) on the rate of reaction (mol dm-3 s-1) for the following chemical reaction:
CaCO3(s) + HCl(aq) CaCl2(s) + H2O(l) + CO2(g)
Research question:
How does altering concentration (mol dm-3) of hydrochloric acid (HCl) affect the rate of reaction (g/s) for the following reaction:
CaCO3(s) + HCl(aq) CaCl2(s) + H2O(l) + CO2(g)
Background information:
The reaction between calcium carbonate and hydrochloric acid is an example of a neutralization reaction between an acid and a base. Neutralization reactions involve the production of a salt (CaCl2), water (H2O), and sometimes carbon dioxide (CO2). In this instance, since the reactant base involves carbon, the gas carbon dioxide will be formed. This will allow for measurement of the rate of reaction to be established by measuring the mass lost from the reacting mixture over time. The flask containing the reactants will be placed on an electronic balance and at certain time intervals the mass will be recorded.
The manipulation of the independent variable, in this case the concentration of hydrochloric acid (HCl) relies on the collision theory of kinetics. The collision theory stipulates that in order for a chemical reaction to transpire, the reactant particles must possess sufficient energy and the correct collision geometry. There are five main factors which affect the rate of reaction, including temperature, concentration, particle size, pressure and the presence of a catalyst. In this investigation, only the concentration will be altered and the remainder of the variables will be controlled throughout the experiment. By the collision theory, ‘increasing the concentration of reactants increases the rate of reaction’. This can be explained in terms of the number of reactant particles increasing and thus the frequency of successful collision resulting in chemical reaction also increasing. (Ford, 2009)
Hypothesis:
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