Sucrose (C12H22O11) Classify each of the reactions given below as one of the following: Precipitation, acid-base, acid-base with gas formation, oxidation-reduction (redox). Reaction Classification Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) KOH(aq) + HNO3(aq) → H2O(l) + KNO3(aq) MgCO3(s) + 2HCl(aq) → 3MgCl2(aq) + CO2(g) + H2O(l) 2KI(aq) + Pb(NO3)2(aq) → PbI2(s) + 2KNO3(aq) List the specific safety precautions given for this.
The Correct Answer and Explanation is:
Here’s the classification of each given reaction and an explanation, along with relevant safety precautions.
Reaction Classification:
- Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)
Type:Oxidation-Reduction (Redox)- Magnesium is oxidized (0 to +2), and hydrogen is reduced (+1 to 0).
- KOH(aq) + HNO₃(aq) → H₂O(l) + KNO₃(aq)
Type:Acid-Base Reaction- A classic neutralization between a strong base and a strong acid.
- MgCO₃(s) + 2HCl(aq) → MgCl₂(aq) + CO₂(g) + H₂O(l)
Type:Acid-Base with Gas Formation- Acid reacts with carbonate to form salt, water, and carbon dioxide gas.
- 2KI(aq) + Pb(NO₃)₂(aq) → PbI₂(s) + 2KNO₃(aq)
Type:Precipitation Reaction- Formation of yellow solid PbI₂ from aqueous ions.
Safety Precautions for Each Reaction:
- Handling Acids and Bases (HCl, HNO₃, KOH):
- Always wear safety goggles, lab coat, and gloves.
- Work under a fume hood when handling concentrated acids.
- Never add water to acid; add acid to water if dilution is needed.
- Reactions Generating Gas (H₂, CO₂):
- Perform in a well-ventilated area or under a fume hood.
- H₂ gas is flammable—keep away from open flames or sparks.
- Handling Solid Reactants and Products (Mg, MgCO₃, Pb(NO₃)₂, PbI₂):
- Lead salts are toxic—avoid inhalation or skin contact.
- Dispose of lead-containing waste according to hazardous waste protocols.
- General Lab Safety:
- Do not ingest chemicals.
- Wash hands after handling chemicals.
- Know the location of safety showers and eyewash stations.
Explanation
In chemistry, reactions are classified based on the nature of the chemical changes involved. The reaction between magnesium and hydrochloric acid is an oxidation-reduction (redox) reaction. Magnesium is a metal that loses electrons (oxidized), forming Mg²⁺, while hydrogen ions (H⁺) are reduced to hydrogen gas (H₂). This type of reaction is also exothermic and produces flammable gas, requiring careful handling.
The reaction between potassium hydroxide and nitric acid is a classic acid-base neutralization. Here, KOH (a base) donates OH⁻ ions, which react with H⁺ ions from HNO₃ (an acid) to form water. The salt formed is KNO₃. These reactions are typically safe but can still release heat and should be handled with caution.
The reaction of magnesium carbonate with hydrochloric acid is another acid-base reaction, but with gas formation. The carbonate (CO₃²⁻) reacts with H⁺ to form carbon dioxide (CO₂), water, and a salt. The gas evolution makes it more vigorous and possibly messy, necessitating work in a fume hood.
Lastly, the reaction between potassium iodide and lead(II) nitrate results in the formation of a precipitate—lead(II) iodide (PbI₂), a bright yellow solid. This is a precipitation reaction, where insoluble PbI₂ forms from two soluble ionic compounds. Since lead compounds are toxic, special care must be taken to avoid exposure and properly dispose of the waste.
In all reactions, appropriate personal protective equipment (PPE), awareness of chemical hazards, and good laboratory practices are essential to ensure safety and accurate results.
