telier\'s Principle: Observations and Discussion Name part I: Change in concentr
ID: 546987 • Letter: T
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telier's Principle: Observations and Discussion Name part I: Change in concentration Procedure Initial color of the CuS0s solution Color of the solution after NHs is added K Blue Color of the solution after adding HCI liglt Bl When CusO, is mixed with NHs, the following equilibrium is established CU(NHala (aq) is dark blue in color a) Which direction did the equilibrium shift when NH, was added to Cuso? Describe the type of stress this applied to the equilibrium in equation (3) and how the observed shift relieves that stress. Be specific in your answer. When HCl is added it reacts according the following equation: H. (aq) + NH, (aq) NH.. (aq) b) Which direction did the equilibrium in equation (3) shift when HCI was added? Describe the type of stress this applied to the equilibrium in equation (3) and how the observed shift relieves that stress. Be specific in your answer.Explanation / Answer
Cu2+ + 4 NH3 --> Cu(NH3)4+2
a)when ammonia is added to the above reaction because according to lechatelier’s principle increase in concentration at reactant side ,the equilibrium is shifted in such a way to reduce that stress.Therefore,the equilibrium is shifted towards right side.
When HCl is added to ammonia .the reaction proceeds as follows
H+ (aq) +NH3 (aq) NH4++ (aq)
b)In the above condition ,when H+ is added to the system ,there is decrease in the concentration of ammonia, in other words increase in the concentration at product side.Therefore, according to Le chatelier’s principle, the reactions shifts left to relieve the stress caused by the removal of the ammonia.
Sparingly soluble salts:
a) CaCl2, a soluble ionic compound, and sodium carbonate, Na2CO3, also a soluble ionic compound, will react to form CaCO3, an insoluble solid that precipitates out of solution, and sodium chloride, another soluble ionic compound.
b)
The balanced chemical equation for this double replacement reaction looks like this
CaCl2(aq]+Na2CO3(aq]CaCO3(s]+2NaCl(aq]
c)The net ionic equation for the reaction is
Ca2+(aq]+CO23(aq]CaCO3(s] _________(i)
Carbonate ions combine with hydrogen ions in two stages,but i wrote the net reaction
2H+ + CO32- H2 CO3(aq) + C02 (g)+H2O(l)
When HCl is added to the reaction at (i) because of decrease in concentration on reactant side i.e because of increase in concentration on product side the equilibrium is shift towards left side
Part-III
Change in temperature:
Initial color of the solution in sealed test tube
Dark blue
Color of the solution on heating on hot water bath
pink
Color of the solution on cooling on ice bath
Dark blue
The two different coloured Co(II) complex ions, [Co(H2O)6]2+ and [CoCl4]2-, exist together in equilibrium in solution in the presence of chloride ions:
[Co(H2O)6]2+(aq)(pink) + 4Cl-(aq) [CoCl4]2-(aq)(blue) + 6H2O(l)
The equilibrium can be disturbed by changing the chloride ion concentration or by changing the temperature.
effect of temperature
a)when hot water is added ,it will turn blue. Therefore the reaction shifted towards right
If we add the cold water the solution, it will turn pink i.e equilibrium is shifted towards left.
b)Based on the observation ,the reaction [Co(H2O)6]2+(aq) + 4Cl–(aq) [CoCl4]2–(aq) + 6H2O(l) is endothermic. Therefore, in accordance with Le-Chatelier’s principle, when the temperature is raised, the position of the equilibrium will move to the right, forming more of the blue complex ion at the expense of the pink species.
Initial color of the solution in sealed test tube
Dark blue
Color of the solution on heating on hot water bath
pink
Color of the solution on cooling on ice bath
Dark blue
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