chapter 2 section 2

Question 1

What are strong electrolytes?

Answer 1

Substances that dissociate almost completely into ions in water, e.g., NaCl, HCl, NaOH.

Question 2

How does HCl dissociate in water?

Answer 2

HCl + H₂O → H₃O⁺ + Cl⁻ (complete dissociation).

Question 2

Why is K_a very large for strong acids like HCl?

Answer 2

Because almost all HCl molecules dissociate, so [HCl] in solution is very small.

Question 2

How is pH of strong acids/bases calculated?

Answer 2

Directly from their concentration: [H⁺] ≈ [acid]; [OH⁻] ≈ [base].

Question 3

Do ions from strong electrolytes recombine significantly in water?

Answer 3

No, they have little affinity for each other; dissociation is effectively complete

Question 4

What effect do strong electrolytes have on water’s conductivity?

Answer 4

They increase electrical conductivity because they produce many free ions.

Question 5

How is H₃O⁺ commonly represented in acid solutions?

Answer 5

Often written simply as H⁺.

Question 6

Example: pH of 0.1 M NaOH?

Answer 6

pH = 13.

Question 7

Why can the [H₂O] term be ignored in K calculations for strong acids?

Answer 7

Because water concentration is constant in dilute solutions.

Question 7

Example: pH of 1 M HCl?

Answer 7

pH = 0

Question 7

What is a weak electrolyte?

Answer 7

A substance that dissociates only slightly into ions in water, e.g., acetic acid

Question 7

What does a small K_a indicate?

Answer 7

Most molecules remain unionized; ion formation is limited.

Question 7

How to calculate [H⁺] for a weak acid?

Answer 7

Use K_a = [H⁺][A⁻]/[HA]

Question 7

What is the Henderson–Hasselbalch equation?

Answer 7

pH=pKa​+log[A^-]/[HA]

Question 7

When [HA] = [A⁻], what is pH?

Answer 7

pH = pKₐ

Question 7

What does a titration curve show?

Answer 7

pH vs. amount of base added during titration of a weak acid.

Question 7

what is present At the start of titration?

Answer 7

Mostly HA present; small amounts of H⁺ and A⁻.

Question 7

What happens as OH⁻ is added?

Answer 7

pH rises gradually.

Question 7

What is the midpoint of the titration curve?

Answer 7

Half of HA is neutralized, [HA] = [A⁻], pH = pKₐ.

Question 7

What is a polyprotic acid?

Answer 7

An acid with more than one dissociable proton, e.g., H₃PO₄ has three.

Question 8

What happens at each pKₐ during titration?

Answer 8

[Acid] = [Conjugate base]; the solution acts as a buffer.