potassium permaganate + hydrochloric acid

Question

Reacts what it will form

 

Answer 1

This is an oxidation/reduction (redox) reaction.  It isn't quite as straight forward as some other reactions you may have been dealing with.  In this reaction, the oxidation half reaction involves oxidation of Cl^- to Cl₂ gas and reduction half reaction is the reduction of MnO₄^- to Mn2⁺.

Oxidation:  2Cl^- → Cl₂ + 2e^- 

Reduction:  8H⁺ + MnO₄^- + 5e^- → Mn²⁺ + 4H₂O

In order to balance the electrons in the ox and red reactions, we multiply oxidation by 5 and reduction by 2 and then add the two reactions together and cancel where appropriate.  We get...

16H⁺ + 2MnO₄^- + 10Cl^- → 2Mn²⁺ + 8H₂O + 5Cl₂

Then filling in the spectator ions (if you must), you get 

2KMnO₄ + 16HCl → 2MnCl₂ + 5Cl₂ + 2KCl + 8H₂O