Chemical Reactions II: Oxidation/Reduction
5.2 Oxidation of Zinc by Hydrochloric Acid
Subjects: Oxidation/reduction, gas forming reaction, acid properties, net ionic equations, exothermic reactions.
Description: Observation of the oxidation of zinc metal by hydrochloric acid to form hydrogen gas and zinc chloride.
- Mossy zinc (1 piece)
- 1 M Hydrochloric acid, HCl‡
- Petri dish
- Flask (optional)
- Balloons (optional)
‡HCl is located in the cabinet under the hood.
Note: Use the demo camera for displaying the reaction in ISB135.
- Add a small amount of HCl to the Petri dish or flask.
- Add a small piece of zinc metal to the HCl and observe the reaction. Hydrogen gas will be produced.
Optional: Put a balloon over the flask opening to collect the gas. Ignite the balloon.
Discussion: Zinc is oxidized by hydrochloric acid to form zinc chloride. In the process, hydrogen gas is produced. The reaction is given below.
Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)
Zn(s) + 2H+ → Zn2+(aq) + H2(g) (Net ionic equation)
Safety: HCl and zinc chloride are corrosive and can cause skin irritations or burns. Wear appropriate protective equipment, including gloves and safety glasses.
Disposal: Solutions of zinc chloride should be disposed in appropriate hazardous waste container.
References: For a more thorough description and variations see:
1. B.Z. Shakhashiri; Chemical Demonstrations: A Handbook for Teachers of Chemistry; Wisconsin; 1985; Volume 1; p. 25-26.