Investigation of reversible reactions at equilibrium - CuCl2 (s) was added to HCl , NaCl , H2SO4 respectively .
by
crysisfreak69 (student)
Data collection
The table below shows the qualitative observations that were made when CuCl2 (s) was added to HCl , NaCl , H2SO4 respectively .
Data Processing
Experiment 1
Cu (H2O)62+ (aq) + 4Cl- (aq) ⇌ CuCl42- (aq) + 6H2O (l)
When HCl is added to the following equilibrium there is an excess of Cl- ions in the left side of equilibrium . Hence according to Le chatelier’s principle i.e. when a system under equilibrium is stressed the system moves in order to minimize the stress . The position of the equilibrium in the equation above shifts to the left in order to counter the increase in the concentration of the Cl- . More CuCl42- and H2O is produced and hence their ...
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Data Processing
Experiment 1
Cu (H2O)62+ (aq) + 4Cl- (aq) ⇌ CuCl42- (aq) + 6H2O (l)
When HCl is added to the following equilibrium there is an excess of Cl- ions in the left side of equilibrium . Hence according to Le chatelier’s principle i.e. when a system under equilibrium is stressed the system moves in order to minimize the stress . The position of the equilibrium in the equation above shifts to the left in order to counter the increase in the concentration of the Cl- . More CuCl42- and H2O is produced and hence their concentration in the equilibrium increases. The increase in the CuCl42- counts for the change of the color of the solution from cyan to green .
When H2O is added to water there is an increase in the concentration of water in the right hand side , hence in order to overcome the concentration of water the position of the equilibrium shifts to the left . This accounts for the change in the color of the solution from green back to the original color of the solution i.e. cyan
When NaCl is added to the solution NaCl dissociates into Na+ and Cl- ions . There is an excess of Cl- ions in the right hand side of the equilibrium . According to Le chatelier’s principle when a system under equilibrium is stressed , the position of the equilibrium moves such that in order to oppose the stress . Hence in this equation the position of the equilibrium shifts from left to right due to cincrease the in concentration of the Cl- ions .AS the position of the equilibrium shifts to the right the more amount of CuCl42- and H2O is produced and hence their concentration in the equilibrium increases. The increase in the CuCl42- counts for the change of the color of the solution from cyan to green .
When H2O is added to water there is an increase in the concentration of water in the right hand side , hence in order to overcome the concentration of water the position of the equilibrium shifts to the left .
When H2SO4 is added to the solution H2SO4 breaks into H+ ions and SO42- ions . There is an excess of H+ ions in the right hand side of the equation , these extra H+ ions react to form H2O , hence there is an excess of the concentration of water on the right side . According to Le chatelier’s principle when a system under equilibrium is stressed , the position of the equilibrium moves such that in order to oppose the stress .The position of the equilibrium moves to the lkeft in order to overcome this change in the concnetation and hence the color of the solution remains somewhat same , but it fades lightly due to increase in the concentration of H2O .
Experiment 2
2CrO42-(aq) + 2H+ (aq) ⇌ Cr2O72- (aq) + H2O (l)
When sulphuric acid is added to the aqueous potassium chromate there is an increase in the concentration of H+ ions. According to Le Chatelier’s principle when a system under equilibrium is stressed the system moves in order to oppose the stress. Hence in this case as the concentration of H+ ions increase the position of the equilibrium shifts to the right, producing more Chromate ions and water, hence changing the color of the solution from yellow to orange , as the concentration of the H+ ions increase .
When water is added to the solution the concentration of water in the right hand side increases, hence in order to overcome the stress on the equilibrium the position of the equilibrium shifts to the right hand side. Hence this increase in the concentration of the water accounts for the change in color of the solution from orange back to yellow.
Experiment 3
CoCl2 + HCl ⇌ Co(H2O)6+2 + Cl-
When HCl is added to the following equilibrium there is an excess of Cl- ions in the left side of equilibrium . Hence according to Le chatelier’s principle i.e. when a system under equilibrium is stressed the system moves in order to minimize the stress . The position of the equilibrium in the equation above shifts to the left in order to counter the increase in the concentration of the Cl- . More CuCl42- and H2O is produced and hence their concentration in the equilibrium increases. The increase in the CuCl42- counts for the change of the color of the solution from cyan to green .
When H2O is added to water there is an increase in the concentration of water in the right hand side , hence in order to overcome the concentration of water the position of the equilibrium shifts to the left . This accounts for the change in the color of the solution from green back to the original color of the solution i.e. cyan
