Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Chem 2 - Acid-Base Equilibria IX: Salts that Hydrolyze in Water to Affect pH

Chem 2 - Acid-Base Equilibria IX: Salts that Hydrolyze in Water to Affect pH

  • Login to see the comments

Chem 2 - Acid-Base Equilibria IX: Salts that Hydrolyze in Water to Affect pH

  1. 1. Acid-Base Equilibria (Pt. 9) Salts that Hydrolyze in Water to Affect pH By Shawn P. Shields, Ph.D. This work is licensed by Dr. Shawn P. Shields-Maxwell under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
  2. 2. Salts that Hydrolyze in Water Hydrolyzing in Water- What Does This Mean? When an ionic compound (salt) “hydrolyzes,” it means it reacts with water to produce H3O+ or OH.
  3. 3. Recall: Neutralization Reactions An acid and a base react to form water and a “salt”. 𝐇𝐂𝐥 𝐚𝐪 + 𝐍𝐚𝐎𝐇 𝐚𝐪 → 𝐇 𝟐 𝐎 𝐥 + 𝐍𝐚𝐂𝐥(𝐚𝐪) 𝐇𝐂𝐥 𝐚𝐪 + 𝐍𝐇 𝟑 𝐚𝐪 ⇌ 𝐇 𝟐 𝐎 𝐥 + 𝐍𝐇 𝟒 𝐂𝐥(𝐚𝐪) acid “salt” acid “salt” base base
  4. 4. Case 1: React a Strong Acid and a Strong Base An acid and a base react to form water and a “salt”. 𝐇𝐂𝐥 𝐚𝐪 + 𝐍𝐚𝐎𝐇 𝐚𝐪 → 𝐇 𝟐 𝐎 𝐥 + 𝐍𝐚𝐂𝐥(𝐚𝐪) strong acid A NEUTRAL salt is prepared! Why? strong base
  5. 5. Case 1: React a Strong Acid and a Strong Base An acid and a base react to form water and a “salt”. 𝐇𝐂𝐥 𝐚𝐪 + 𝐍𝐚𝐎𝐇 𝐚𝐪 → 𝐇 𝟐 𝐎 𝐥 + 𝐍𝐚𝐂𝐥(𝐚𝐪) The conjugate acid of a strong base (Na+) is NOT acidic in water. The conjugate base of a strong acid (Cl) is NOT basic in water.
  6. 6. Case 2: React a Strong Acid and a Weak Base An acid and a base react to form water and a “salt”. 𝐇𝐂𝐥 𝐚𝐪 + 𝐍𝐇 𝟑 𝐚𝐪 ⇌ 𝐇 𝟐 𝐎 𝐥 + 𝐍𝐇 𝟒 𝐂𝐥(𝐚𝐪) strong acid An ACIDIC salt is prepared! Why? weak base
  7. 7. Case 2: React a Strong Acid and a Weak Base Add NH4Cl to water… 𝐍𝐇 𝟒 𝐂𝐥(𝐚𝐪) + 𝐇 𝟐 𝐎 𝐥 ⇌ 𝐂𝐥− 𝐚𝐪 + 𝐍𝐇 𝟒 + (𝐚𝐪) The conjugate base of a strong acid (Cl) is NOT basic in water. The conjugate acid (NH4 +) of a weak base (NH3) IS acidic in water. “salt” weak ACID!
  8. 8. Case 3: React a Strong Base and a Weak Acid An acid and a base react to form water and a “salt”. 𝐊𝐎𝐇 𝐚𝐪 + 𝐇𝐅 𝐚𝐪 ⇌ 𝐇 𝟐 𝐎 𝐥 + 𝐊𝐅(𝐚𝐪) strong base A BASIC salt is prepared! Why? weak acid
  9. 9. Case 3: React a Strong Acid and a Weak Base Add KF to water… 𝐊𝐅 (𝐚𝐪) + 𝐇 𝟐 𝐎 𝐥 ⇌ 𝐊+ 𝐚𝐪 + 𝐅− (𝐚𝐪) The conjugate acid of a strong base (K+) is NOT acidic in water. The conjugate base (F) of a weak acid (HF) IS basic in water. “salt” weak BASE!
  10. 10. Next up, Buffers and the Henderson- Hasselbalch Equation (Pt 10)

×