Acids and Bases

Summary and Exam Tips for Acids and Bases

Acids and Bases is a subtopic of Acids-Bases, which falls under the subject Chemistry in the IB DP curriculum. This unit explores the Lewis Theory and Brønsted-Lowry Theory of acids and bases. According to Lewis, a Lewis acid is an electron pair acceptor, while a Lewis base is an electron pair donor. The Brønsted-Lowry theory defines acids as proton donors and bases as proton acceptors. The unit also covers weak acids and bases, which partially dissociate in solution, and their equilibrium constants, $K_a$ and $K_b$. Understanding pH curves is crucial, as they provide insights into acid-base reactions and equivalence points. The unit also delves into buffer solutions, which resist pH changes, and salt hydrolysis, which affects the pH of solutions. Calculations involving pH, pOH, and dissociation constants are essential for mastering this topic. The relationship between $K_a$, $K_b$, and $K_w$ is also explored, highlighting the importance of equilibrium in aqueous solutions.

Exam Tips

• Understand Key Theories: Be clear on the definitions and differences between Lewis and Brønsted-Lowry acids and bases.
• Master pH Calculations: Practice calculating pH, pOH, and using $K_a$ and $K_b$ values. Remember, $pH = -\log [H_3O^+]$.
• Interpret pH Curves: Familiarize yourself with the shape and significance of pH curves, especially the equivalence point.
• Buffer Solutions: Know how buffers work and their role in maintaining pH stability.
• Salt Hydrolysis: Understand how the strength of acids and bases affects the pH of the resulting solution.