Investigating Chemical Equilibria
The aim of this experiment is to study the effect of concentration changes on equilibria.In some chemical systems the energies of the reactants and the products are of a similar order of magnitude so that the reaction is reversible, that is, it can take place in either direction. If such a system is established in a closed vessel, so that no gases could escape, then a chemical equilibrium is established. The forward and the reversible reaction have the same rate. So, if for example we take the reversible reaction A+B"c C+D, then the initially forward reaction occurs rapidly, but as the concentration of the reactants falls, the rate decreases. The reverse reaction initially cannot occur at all, but as the products start to form, its rate increases. Consequently, the rate of the two reactions becomes equal, the concentrations reach constant values and the equilibrium is established.There are conditions, such as the temperature, the pressure and the concentration. According to Le Chatelier's principle, "if a change is made to the conditions of a chemical equilibrium, then the position of a chemical equilibrium will readjust so as to minimise the change made".
If temperature is increased, the endothermic reaction is favored, whereas, if temperature is decreased, the exothermic reaction is favored. Afterwards, we should add an amount of HCl until we see a change in the color. That is, the position of the equilibrium shifts to the opposite side, to the right. Then by using a pipette, we add drop by drop 1. 59gDATA AND OBSERVATIONS:Investigation 1 Since, we have established the equilibrium Cr2O7-2 + H2O "c 2CrO4-2 + 2H+, we add an amount of sodium hydroxide until the color changes. If pressure is increased, then the equilibrium will shift to the side where the most gaseous molecules exist, whereas if pressure is decreased, the equilibrium will shift to the side where the least gaseous molecules exist. CALCULATIONS:Investigation 1K2Cr2O7 : c = n /v"³ n = c x v "³ n = 0. Cu+2 + NH3 "c Cu (NH3)4+2Blue royal blueBecause we want to see the effect of decreasing the concentration of copper ions, we add concentrated ammonia. Cu(OH)2 "c Cu+2 + 2OH-Pale blue blueIn Investigation 2, the solution of CuSO4 and water, which color is light blue, becomes blue and the precipitate, copper ions are formed, when sodium hydroxide is added. CuSO4 * 5H2O "c CuSO4 + 5H2OPurple whiteAccording to the above reversible reaction, copper (II) sulphate pentahydrate is a purple solid that when heated, it decomposes to copper sulphate, a white solid and water. 9 m = n x MM "³ m = 0.
Common topics in this essay:
Le Chatelier's,
METHOD Investigation,
NH34+2 Blue,
CALCULATIONS Investigation,
CuSO4 H2O,
OBSERVATIONS Investigation,
,
CuOH2 Cu+2,
A+Bc C+D,
Copper II,
³ =,
copper ii sulphate,
ii sulphate,
copper ii,
color solution,
test tube,
sulphate pentahydrate,
ii sulphate pentahydrate,
copper ions,
shifts opposite,
distilled water,
equilibrium shifts opposite,
ml distilled,
ml distilled water,
10 ml distilled,
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