Answer the following questions for these salts: Co(OCl)2, Ba(NO3)2, and NH4Br. [a] Write an acid-base reaction for each of the salts listed above in which the salt is the product in the neutralization reaction. [b] Using the equations in part a, identify the chemicals as: strong acids (SA), strong bases (SB), weak acids (WA), and weak bases (WB). [c] Using the information in part b, identify whether each cation and anion in each salt is a spectator ion (S), or is capable of hydrolysis (H). [d] For each ion capable of hydrolysis, write the correct hydrolysis equation. 3] Complete Table 10.1 by indicating whether the solution is A (acidic), B (basic) or N (neutral), and classify the ions as either spectators or capable of hydrolysis. Solution: Indicate acidic (A), basic (B), or neutral (N) to Hydrolyze Ions. NaCH3O2: B, CH3O2: Na* Cu(NO3)2: A, Cu2+, NO3 NH4Br: N, NH4, Br NaHCO3: B, HCO3, Na KH2PO4: B, H2PO4, K CaOCl2: B, OCl2, Ca Ba(NO2)2: N, Ba, NO2 KHPO4: B, HPO4, K
The Correct Answer and Explanation is:
Step-by-Step Analysis
(a) Acid-Base Neutralization Reactions
Each salt results from a reaction between an acid and a base:
- Cobalt hypochlorite – Co(OCl)₂
Co(OH)2+2HOCl→Co(OCl)2+2H2OCo(OH)₂ + 2HOCl \rightarrow Co(OCl)₂ + 2H₂O
Cobalt(II) hydroxide (weak base) reacts with hypochlorous acid (weak acid).
- Barium nitrate – Ba(NO₃)₂
Ba(OH)2+2HNO3→Ba(NO3)2+2H2OBa(OH)₂ + 2HNO₃ \rightarrow Ba(NO₃)₂ + 2H₂O
Barium hydroxide (strong base) reacts with nitric acid (strong acid).
- Ammonium bromide – NH₄Br
NH3+HBr→NH4BrNH₃ + HBr \rightarrow NH₄Br
Ammonia (weak base) reacts with hydrobromic acid (strong acid).
(b) Classification of Acids and Bases
- Co(OCl)₂: Hypochlorous acid (WA), cobalt(II) hydroxide (WB)
- Ba(NO₃)₂: Nitric acid (SA), barium hydroxide (SB)
- NH₄Br: Hydrobromic acid (SA), ammonia (WB)
(c) Spectator Ions & Hydrolysis
- Co²⁺ (H), OCl⁻ (H) → Both hydrolyze.
- Ba²⁺ (S), NO₃⁻ (S) → Spectator ions.
- NH₄⁺ (H), Br⁻ (S) → Ammonium hydrolyzes, bromide is a spectator.
(d) Hydrolysis Reactions
- Cobalt(II) ion hydrolysis:
Co2++H2O⇌CoOH++H+Co²⁺ + H₂O \rightleftharpoons CoOH⁺ + H⁺
- Hypochlorite ion hydrolysis:
OCl−+H2O⇌HOCl+OH−OCl⁻ + H₂O \rightleftharpoons HOCl + OH⁻
- Ammonium ion hydrolysis:
NH4++H2O⇌NH3+H3O+NH₄⁺ + H₂O \rightleftharpoons NH₃ + H₃O⁺
Final Classification
| Salt | Solution | Hydrolyzed Ions | Spectator Ions |
|---|---|---|---|
| Co(OCl)₂ | Acidic (A) | Co²⁺, OCl⁻ | – |
| Ba(NO₃)₂ | Neutral (N) | – | Ba²⁺, NO₃⁻ |
| NH₄Br | Acidic (A) | NH₄⁺ | Br⁻ |
A clear understanding of hydrolysis allows accurate pH predictions, affecting solubility and reactivity. Solutions containing salts of strong acids and strong bases remain neutral, whereas salts with weak acid or weak base components hydrolyze, influencing pH.
