Which substance is the reducing agent in this reaction? 2kmno4+3na2so3+h2o→2mno2+3na2so4+2k oh

Reducing agent:

Explanation:

Reducing species is a chemical species which itself undergoes oxidation and reduces other chemical species in a redox reaction.

Oxidation state of each element is:

Before the reaction                                           After the reaction

Oxidation state of K = +1                       Oxidation state of Mn = +4

Oxidation state of Mn = +7                      Oxidation state of O = -2

Oxidation state of O = -2                                      

Before the reaction                                           After the reaction

Oxidation state of Na = +1                   Oxidation state of Na = +1

Oxidation state of S = +4                      Oxidation state of S = +6

Oxidation state of O = -2                        Oxidation state of O = -2

Only oxidation states of S and Mn are changes during the reaction.

Oxidation of Mn is decreased and oxidation number of S is increased during the reaction. Hence, undergoes oxidation, so acts as reducing agent.

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2