Suppression of the Ionization of Ammonium Hydroxide
Description: Two equimolar solutions of Ammonium hydroxide are treated with phenolphthalein indicator. A bright pink color is noted in each. Ammonium chloride is added to one beaker of solution and not to the other. The color of the solution in the ammonium chloride treated beaker fades in color noticeably.
NH4OH(aq) ↔ NH4+(aq) + OH–(aq)
NH4Cl(aq) → NH4+(aq) + Cl–(aq)
2NH4+(aq) + Cl–(aq) + OH–(aq) → NH3(g) + H2O(l) + NH4+(aq) + Cl–(aq)
NH4Cl(s)+ NH4OH(aq) → NH3(g) + H2O(l) + Cl–(aq) + NH4+(aq)
Source: UW Card Catalog
Year: N/A Vol: N/A Page: N/A
Keywords: Equilibrium, Indicator, Common ion effect, Le Chatelier’s principle
Rating: 
Hazard: Some
- Acute toxicity- oral
- Skin corrosion hazard
- Serious eye damage
- Specific target organ toxicity- single exposure- respiratory system
- Short-term (acute) aquatic hazard
- Eye irritation
- Germ cell mutagenicity
- Carcinogenicity
- Reproductive toxicity
- Electric shock hazard
Effectiveness: Average
- Results are observable with guidance
- Secondary effects are observed
- Mild effects are observed by audience
- Time to results is low
- Good reliability
Difficulty: Low
- Simple addition of reagents
- Simple procedures
- Simple manipulations for most to perform
- Demos at standard conditions
Safety Precautions:
- Eye protection required
- Gloves required
- Perform in a well-ventilated area
- Avoid exposure to dusts, mists, and vapors
- Use UL approved three-prong plug and outlet
- Prevent release of reagents to the environment
Class: Aqueous Equilibrium and Precipitation Reactions
Division: General