# Acid-base problems and solutions

1. What is an acid according to Arrhenius theory? Solution: According to Arrhenius theory, an acid is a substance that dissociates in water to produce H⁺ ions.

2. What is a base according to Arrhenius theory? Solution: According to Arrhenius theory, a base is a substance that dissociates in water to produce OH⁻ ions.
3. What is a conjugate acid-base pair? Solution: A conjugate acid-base pair consists of two substances related to each other by the donating and accepting of a single hydrogen ion. The acid donates a proton (H⁺ ion) and the base accepts a proton.
4. What is pH? Solution: pH is a measure of the hydronium ion (H₃O⁺) concentration in a solution. It is defined as the negative logarithm (base 10) of the molar concentration of hydronium ions in the solution.
5. What is the pH of a neutral solution at 25°C? Solution: The pH of a neutral solution at 25°C is 7.
6. What is pOH? Solution: pOH is a measure of the hydroxide ion (OH⁻) concentration in a solution. It is defined as the negative logarithm (base 10) of the molar concentration of hydroxide ions in the solution.
7. What is the relationship between pH and pOH at 25°C? Solution: At 25°C, the sum of pH and pOH equals 14.
8. What is the difference between a strong acid and a weak acid? Solution: A strong acid completely ionizes (dissociates) in solution, whereas a weak acid only partially ionizes.
9. What is the difference between a strong base and a weak base? Solution: A strong base completely ionizes in solution, whereas a weak base only partially ionizes.
10. What is an amphoteric substance? Solution: An amphoteric substance is a substance that can act as both an acid and a base. Water is an example of an amphoteric substance.
11. What are Bronsted-Lowry acids and bases? Solution: According to the Bronsted-Lowry definition, an acid is a proton donor and a base is a proton acceptor.
12. How do you calculate pH from H⁺ ion concentration? Solution: The pH is calculated as the negative logarithm (base 10) of the H⁺ ion concentration: pH = -log[H⁺].
13. What is the Ka value of an acid? Solution: The Ka value, or the acid dissociation constant, is a measure of the strength of an acid in solution. It is the equilibrium constant for the reaction of the acid with water to form hydronium ions and the conjugate base.
14. What is the Kb value of a base? Solution: The Kb value, or the base dissociation constant, is a measure of the strength of a base in solution. It is the equilibrium constant for the reaction of the base with water to form hydroxide ions and the conjugate acid.
15. What is a titration? Solution: A titration is a procedure used in analytical chemistry to determine the concentration of an acid or base. It involves the addition of a solution of known concentration (the titrant) to a solution of unknown concentration (the analyte) until the reaction between them is just complete.
16. What is the equivalence point in a titration? Solution: The equivalence point in a titration is the point at which the reaction between the titrant and the analyte is complete. In an acid-base titration, it is the point at which the amount of acid equals the amount of base.
17. What is the end point in a titration? Solution: The end point in a titration is the point at which an indicator changes color to signal that the equivalence point has been reached.
18. How do you choose an appropriate indicator for a titration? Solution: An appropriate indicator for a titration is chosen based on the pH at the equivalence point of the titration. The indicator should change color at or near this pH.
19. What is the purpose of a buffer solution in a titration? Solution: A buffer solution in a titration helps maintain a constant pH when small amounts of acid or base are added. It can be used to stabilize the pH near the equivalence point to improve the accuracy of the titration.
20. What does the term “neutralization” mean in the context of acid-base reactions? Solution: Neutralization in acid-base reactions refers to the process by which an acid reacts with a base to produce water and a salt, thereby neutralizing each other. The resulting solution is often close to neutral pH (pH 7)