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The following chemical equation represents the reaction that occurs when methylamine dissolves in water to form a basic solution. CH3NH2(aq) + H2O(l) → CH,NH3" (aq) + OH (aq) The pH of 2.65M CH3NH2(aq) is 12.54. Determine the value of Kb for methylamine.
The following chemical equation represents the reaction that occurs when methylamine dissolves in water to form a basic solution. CH3NH2(aq) + H2O(l) → CH,NH3" (aq) + OH (aq) The pH of 2.65M CH3NH2(aq) is 12.54. Determine the value of Kb for methylamine.
Final answer:To find the Kb for methylamine, calculate pOH from the given pH, then use the resulting [OH⁻] value and the initial concentration of methylamine to determine the base dissociation constant (Kb).Explanation:To determine the value of Kb for methylamine, we can use the provided pH level and the concentration of the solution. The pH of a solution is related to the pOH by the equation pH + pOH = 14.Given the pH level of 12.54, we can calculate the pOH as 14 - 12.54 = 1.46. The concentration of OH- ions is then 10-pOH = 10-1.46, which can be calculated as approximately 0.0347 M.In a basic solution, the concentration of the OH⁻ ions ([OH⁻]) equals the concentration of the conjugate acid, which is created when the base accepts a proton.Knowing that the initial concentration of methylamine was 2.65 M and assuming that the change in concentration due to the reaction is negligible (as the base is weak and only partially dissociates), we can express the base dissociation constant as Kb = [CH₃NH₃⁺][OH⁻] / [CH₃NH₂].Since [CH₃NH₃⁺] = [OH⁻], the expression simplifies to Kb = [OH⁻]² / [CH₃NH₂]. By substituting the values, we obtain Kb = (0.0347)² / 2.65, which yields the value of Kb for methylamine....