Match each chemical reaction or treatment involving an acid or base on the left with its corresponding characteristic chemical observation or property on the right.
- Heating aqueous sodium hydroxide with ammonium chlorideLiberation of a pungent alkaline gas that turns damp red litmus paper blue
- Treating iron(II) sulfide with dilute hydrochloric acidLiberation of a gas with a rotten-egg odor that turns lead(II) ethanoate paper black
- Adding concentrated tetraoxosulfate(VI) acid to cane sugarDehydration producing a black spongy mass of carbon and evolution of steam
- Reacting copper turnings with moderately concentrated trioxonitrate(V) acidLiberation of a gas that forms reddish-brown fumes on contact with air
Answer
Heating aqueous sodium hydroxide with ammonium chloride matches the liberation of a pungent alkaline gas that turns damp red litmus paper blue; treating iron(II) sulfide with dilute hydrochloric acid matches the liberation of a gas with a rotten-egg odor that turns lead(II) ethanoate paper black; adding concentrated tetraoxosulfate(VI) acid to cane sugar matches dehydration producing a black spongy mass of carbon and steam; reacting copper turnings with moderately concentrated trioxonitrate(V) acid matches the liberation of a gas that forms reddish-brown fumes on contact with air.
Each acid or base reaction produces a distinct diagnostic observation: strong bases liberate ammonia gas from ammonium salts; dilute acids liberate hydrogen sulfide from sulfides; concentrated sulfuric acid dehydrates carbohydrates to elemental carbon; and nitric acid oxidizes metals to yield nitrogen oxides.
Step-by-Step Solution
Key Concept
Chemical properties and characteristic reactions of acids and bases