In the redox reaction, which is the reducing agent? #MnO2(s) + 4H(aq) + 2Cl^(-)(aq) -> Mn^(2+)(aq) + 2H_2O + Cl_2(g)#?
By checking the changes that occur in their oxidation numbers, we see that
The simplest way to determine the reducing agent (or the oxidizing agent for that mattter) is to determine the oxidation number of each atom in the equation.
By the way, I think the equation you have given should have the second substance written as
So, we will focus on the Mn atoms and the Cl atoms as these will have changes in their oxidation numbers.
Looking at the products, the
At the same time, the chlorine atom increases to an oxidation number of zero (in its element form as