12.3.1 Degree of Ionization

• The degree of ionization, denoted by α, refers to the fraction or percentage of molecules of an acid or base that dissociate or ionize
• For strong acids and bases, the degree of ionization (α) is close to 1 or 100%.
• If 100 molecules of acetic acid are dissolved in water and only 2 molecules ionize, the degree of ionization is 0.02
• Strong acids have a degree of ionization close to 100%.
• Weak acids only partially ionize in water, with a degree of ionization less than 100
• Arrange the following properties to differentiate between strong and weak acids:

  1️⃣ Ionization in water: Complete vs. Partial

  2️⃣ Degree of ionization: Near 100% vs. < 100%

  3️⃣ Examples: HCl vs. CH_3COOH
• The equation for strong acid dissociation, such as HCl, is HCl(aq) \rightarrow H^ + (aq) + Cl^ - (aq)</latex>, indicating complete ionization
• Acetic acid is an example of a weak acid.
• Strong bases completely ionize in water, releasing all their hydroxide ions, with a degree of ionization close to 100
• Match the type of base with its example:

  Strong base ↔️ NaOH

  Weak base ↔️ NH_3
• The equation for strong base dissociation, such as NaOH, is $NaOH(aq) \rightarrow Na^ +$$(aq) +$$OH^ - (aq)$.
• The equation for weak base ionization, such as ammonia, is NH_{3}(aq) + H_{2}O(l) \rightleftharpoons NH_{4}^ + (aq) + OH^ - (aq)</latex>, indicating partial ionization
• For strong acids and bases, the degree of ionization (α) is close to 1 (100%).
• If 100 molecules of acetic acid ($CH_{3}COOH$) are dissolved in water and only 2 molecules ionize, the degree of ionization is 0.02
• Match the property with the correct type of acid or base:

  Complete ionization ↔️ Strong acids/bases

  Partial ionization ↔️ Weak acids/bases
• Arrange the following steps to calculate the degree of ionization:

  1️⃣ Determine the number of molecules ionized

  2️⃣ Determine the total number of molecules dissolved

  3️⃣ Apply the formula: $\alpha =$$\frac{\text{Number of molecules ionized}}{\text{Total number of molecules dissolved}}$
• For weak acids and bases, the degree of ionization (α) is much less than 1.
• If 100 molecules of acetic acid ($CH_{3}COOH$) are dissolved in water and only 2 molecules ionize, the degree of ionization is 0.02
• What is the degree of ionization for strong acids?

  Close to 100%
• Examples of strong acids include HCl
• Write the equation for the dissociation of a strong acid, such as HCl.

  HCl(aq) \rightarrow H^ + (aq) + Cl^ - (aq)</latex>
• Strong bases have a degree of ionization close to 100%.
• A weak base example is ammonia
• Write the equation for the dissociation of a strong base, such as NaOH.

  NaOH(aq) \rightarrow Na^ + (aq) + OH^ - (aq)</latex>
• The degree of ionization indicates the strength of an acid.
• The formula for degree of ionization is $\alpha =$$\frac{\text{Number of molecules ionized}}{\text{Total number of molecules dissolved}}$
• What is the degree of ionization for acetic acid if 2 out of 100 molecules ionize?

  0.02 or 2%
• How does temperature affect the degree of ionization for weak acids?

  Increases it
• Weak acids have a degree of ionization much less than 100%