Laboratory Preparation of Chlorine
Chlorine can be prepared in the laboratory by reacting manganese dioxide (MnO₂) with concentrated hydrochloric acid (HCl). This reaction occurs as follows:
-
Materials Required:
- Manganese dioxide (MnO₂)
- Concentrated hydrochloric acid (HCl)
- Test tube or reaction vessel
- Delivery tube
- Water trough (for gas collection)
-
Procedure:
- Place a small amount of MnO₂ in a test tube.
- Carefully add concentrated HCl to the MnO₂.
- Heat the mixture gently to initiate the reaction.
- Chlorine gas will evolve, which can be collected using a water trough.
-
Chemical Equation: The reaction can be represented by the following equation:
[ \text{MnO}_2 + 4\text{HCl} \rightarrow \text{MnCl}_2 + 2\text{H}_2\text{O} + \text{Cl}_2 ]
In this reaction, manganese dioxide acts as an oxidizing agent, and chlorine gas is produced as one of the products, along with manganese(II) chloride and water. This method is effective for generating chlorine gas in a controlled laboratory setting.
Key points to remember
- Chlorine is prepared using MnO₂ and concentrated HCl.
- The reaction produces chlorine gas, MnCl₂, and water.
- The balanced equation is MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂.
- Use appropriate safety measures when handling concentrated HCl.
- Collect chlorine gas using a water trough method.
Worked example
Describe the laboratory preparation of chlorine gas from MnO₂ and HCl.
- Mix MnO₂ with concentrated HCl in a test tube.
- Heat gently to produce Cl₂ gas, MnCl₂, and water.
- Equation: MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂.