Lab 2- Chemical Equilibrium And Le Chatalier’s Principle Flashcards
(10 cards)
In the example of the following reaction, what is the rate of formation of hydrogen iodide proportional to?
H2+ I2 —> 2HI
The rate of formation of hydrogen iodide must be proportional to the number of effective collisions between hydrogen molecules and iodine atoms.
What happens if more hydrogen is added to the container?
The concentration of hydrogen gas will increase and there would be more collisions per second, and therefore an increase in the rate of the forward reaction.
What happens if hydrogen gas is removed from the container?
There will be fewer collisions per second between hydrogen molecules and iodine atoms, resulting in a slower forward reaction. The reverse reaction will predominate until a new equilibrium is established.
What is Le Chatalier’s Principle?
When some stress is applied to a system originally in equilibrium, the system (reaction) will automatically shift in such a direction as to relieve the stress and restore the original conditions as much as possible.
What is an important reaction to know for this experiment? What happens to this reaction in 0.1 M HCl is dissolved in water?
H2O —-> H(+) + OH(-) ; Kc= [H+][OH-]= 1 x 10^-14
In aqueous solution, this reaction must always be present.
If 0.1M HCl is dissolved in water, it dissociates to produce a solution 0.1M in H+ ions and 0.1M in Cl- ions. At his reaction must occur in such a direction to maintain the equilibrium. So, [OH-], which in pure water is 1 x 10^-7M is lowered by shift in reaction to the left and the new value for it is 1 x 10^-13M.
What is unique to chemicals called acid-base indicators?
They change color in solution in response to the change in the concentration of the hydrogen ion.
What is the color of methyl violet in its acidic form?
HMV will appear greenish rather than yellow, except in very acidic solutions.
How do many metal ions exist in solutions?
They exist in solutions as complex ions, with the central metal ion bonded to other ions or molecules called ligands. Complex ions may be converted to other complex ions by addition or replacement of the ligands.
The cobalt (II) ions form the _____ complex ion Co(H2O)6 (2+) in aqueous solution. Chloride ligands can replace water ligands to form the ion CoCl4 (2-). This ion, which is _____, is stable in solutions with a large concentration of Cl-.
Pink-Blue
What is an example of a ionic substance that exhibits very small solubility? What is the significance?
Lead Chloride (PbCl2) ; for the equilibrium to exist there must always be some PbCl2 present, even though it does not enter the expression for the equilibrium constant because it is a solid. The equilibrium constant for such a mixture is called the solubility product, given by the symbol Ksp.
