Determine the pH of each of the following solutions (Ka and Kb values are given in Appendix D): (c) 0.165 M hydroxylamine.

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Identify that hydroxylamine (NH2OH) is a weak base and will partially dissociate in water.

Write the equilibrium expression for the dissociation of hydroxylamine: NH2OH + H2O \(\rightleftharpoons\) NH3OH^+ + OH^-.

Use the given concentration of hydroxylamine (0.165 M) as the initial concentration in the ICE table.

Set up the expression for the base dissociation constant (Kb) using the equilibrium concentrations from the ICE table: Kb = \(\frac{[NH3OH^+][OH^-]}{[NH2OH]}\).

Solve for the hydroxide ion concentration [OH^-] using the Kb value, then calculate the pOH and finally the pH using the relation pH + pOH = 14.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Acid-Base Theory

Acid-base theory explains the behavior of acids and bases in solution. According to the Brønsted-Lowry theory, acids are proton donors and bases are proton acceptors. Hydroxylamine (NH2OH) can act as a weak base, accepting protons from water to form hydroxylammonium ions (NH3OH+), which is essential for calculating the pH of the solution.

Dissociation Constants (Ka and Kb)

Dissociation constants, Ka for acids and Kb for bases, quantify the strength of an acid or base in solution. For hydroxylamine, the Kb value is used to determine how much it dissociates in water. The relationship between Kb and pH is crucial for calculating the concentration of hydroxylammonium ions and the resulting pH of the solution.

pH Calculation

pH is a measure of the hydrogen ion concentration in a solution, calculated using the formula pH = -log[H+]. For weak bases like hydroxylamine, the pH can be determined by first calculating the concentration of hydroxide ions (OH-) produced, then using the relationship between pH, pOH, and the ion product of water (Kw) to find the final pH value.