Final answer:
To determine the pH of the solution, we need to calculate the hydroxide ion concentration using the ionization constant (Kb) of the weak base CH₃NH₂. We then use this concentration to calculate the pOH and pH of the solution.
Step-by-step explanation:
To determine the pH of 50 mL of 0.4 M CH₃NH₂ solution, we need to calculate the concentration of hydroxide ions (OH⁻) using the ionization constant (Kb) provided. Kb represents the equilibrium constant for the base's reaction with water. In this case, CH₃NH₂ is a weak base.
First, we calculate the concentration of CH₃NH₂ from the given molarity and volume: 0.4 M x 0.050 L = 0.02 mol. Next, we use the Kb value to determine the concentration of OH⁻ ions produced when CH₃NH₂ reacts with water. Finally, we calculate the pOH and pH using the concentrations of H⁺ and OH⁻ ions.
The pH can be calculated using the pOH formula: pH = 14 - pOH. Since pOH is equal to -log[OH⁻], we will use that value to calculate the pH.