Problem: Write equations for the half-reactions that occur in the electrolysis of a mixture of molten potassium bromide and molten lithium bromide.

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We’re being asked to write equations for the half-reactions that occur in the electrolysis of a mixture of molten potassium bromide and molten lithium bromide.


First, we will write the correct formula of the given compounds (refer to periodic Table):


  • potassium bromide = KBr
  • lithium bromide = KBr
    • K = Potassium, Group 1A, charge = +1
    • Li = Lithium, Group 1A, charge = +1
    • Br = Bromine (changed ending to ide in an ionic compound)
      • Group 7A, charge = -1
      • For ionic compounds with the same charges no need to write subscript


Recall that the cathode is where reduction occurs while the anode is where oxidation occurs.


Since both KBr and LiBr are ionic compounds, they form ions (dissociate) in solution: 


  • KBr  K+(aq) + Br(aq)
  • LiBr  Li+(aq) + Br(aq)


During electrolysis, the cation is reduced/gains electrons while the anion is oxidized/loses electrons

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Problem Details

Write equations for the half-reactions that occur in the electrolysis of a mixture of molten potassium bromide and molten lithium bromide.

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What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Electrolysis of Water & Mixture of Ions concept. If you need more Electrolysis of Water & Mixture of Ions practice, you can also practice Electrolysis of Water & Mixture of Ions practice problems.