Answer: Equilibrium concentration of [tex][Cl^-][/tex] at [tex]50^0C[/tex] is 4.538 M
Explanation:
Initial concentration of [tex]CoCl_2[/tex] = 0.056 M
Initial concentration of [tex]Cl^-[/tex] = 4.60 M
The given balanced equilibrium reaction is,
[tex]COCl_2+2Cl^-\rightleftharpoons [CoCl_4]^{2-}+6H_2O[/tex]
Initial conc. 0.056 M 4.60 M 0 M 0 M
At eqm. conc. (0.056-x) M (4.60-2x) M (x) M (6x) M
The expression for equilibrium constant for this reaction will be,
[tex]K_c=\frac{[CoCl_4]^{2-}\times [H_2O]^6}{[CoCl_2]^2\times [Cl^-]^2}[/tex]
Given : equilibrium concentration of [tex][CoCl_4]^{2-}[/tex] =x = 0.031 M
Concentration of [tex]Cl^-[/tex] = (4.60-2x) M = [tex](4.60-2\times 0.031)[/tex] =4.538 M
Thus equilibrium concentration of [tex][Cl^-][/tex] at [tex]50^0C[/tex] is 4.538 M
The equilibrium concentration of Cl⁻ at 50°C is 4.54 M, after the solution of 0.056 M CoCl₂·6H₂O with 4.60 M HCl is heated in a water bath to 50°C. It was calculated knowing that the equilibrium concentration of CoCl₄²⁻ at 50°C is 0.031 M.
The reaction between CoCl₂·6H₂O and HCl is the following:
CoCl₂·6H₂O + 2HCl → H₂CoCl₄ + 6H₂O
The initial concentrations are:
[CoCl₂·6H₂O] = 0.056 M
[HCl] = 4.60 M
At equilibrium, we have:
CoCl₂·6H₂O + 2HCl → H₂CoCl₄ + 6H₂O
0.056-x 4.60-2x x 6x
We know that the CoCl₄²⁻ concentration at equilibrium is 0.031 M, so:
[tex] [CoCl4^{-2}] = x = 0.031 M [/tex]
With this, we can find the equilibrium concentration of Cl⁻ and CoCl₂·6H₂O:
[tex] [Cl^{-}] = (4.60 - 2*0.031) M = 4.54 M [/tex]
[tex] [CoCl_{2}\cdot 6H_{2}O] = (0.056 - 0.031) M = 0.025 M [/tex]
Therefore, the equilibrium concentration of Cl⁻ is 4.54 M.
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