Question

          

1. The above is a simplified diagram of the Downs Cell used for the manufacture of sodium. Study it and answer the questions that follow.
   1. What material is the anode made of? Give a reason  
   2. What precaution is taken to prevent chlorine and sodium from re- combination? 
   3. Write an ionic equation for the reaction in which chlorine gas is formed    
2. In the Downs process, (used for manufacture of sodium), a certain salt is added to lower the melting point of sodium chloride from about 800°C to about 600°C.
   1. Name the salt that is added  
   2. State why it is necessary to lower the temperature     
3. Explain why aqueous sodium chloride is not suitable as an electrolyte for the manufacture of sodium in the Downs process  
4. Sodium metal reacts with air to form two oxides. Give the formulae of two oxides   

Answer 1

1.  
   1. Graphite
      Does not react with products of electrolysis.
   2. Steel gauze diaphram is used to separate the Anode from cathode
   3. 2Cl(aq) → Cl₂(g) + 2e⁻
2.  
   1. Cryolite
   2. Reduce the amount of energy used hence lower cost
3. H⁺ will be preferentially discharged hence H₂(g) will be produced instead of Na.
4. Na₂O(s)/Na₂O₂