Identifying redox reaction

[kettles]

Hey guys, how would you know if something is a redox reaction by just looking at the equation? What are the keys which distinguishes this equation from a standard acid/base or a precipitation.

example


Which of the following reactions would be classes as a redox reaction?

a) 6CO2(g)+6H2O(l)==>C6H12O6(aq)+6O2(g)
b)CaC2(s)+2H2O(l)==>Ca(OH)2(aq)+C2H2(g)
c)H2SO4(aq)+Ca(HCO3)2(s)==>CaSO4(aq)+2H2O(l)
d)FeS(s)+2HCl(aq)=>FeCl2(aq)+H2S(g)

[destain]

I think you would check to see if there is a change in the oxidation numbers?
Correct me if im wrong...

[Nobby]

I think you can also just skim over the reactants are products for some reactions; i.e. if you have O₂ or Cl₂ or some other homonuclear product it must be redox

[Shenz0r]

Looking at oxidation numbers will definitely tell you if it's a redox reaction

[kettles]

shen can yo udo this question so i can see your work process.

[Shenz0r]

Which of the following reactions would be classes as a redox reaction?

a) 6CO2(g)+6H2O(l)==>C6H12O6(aq)+6O2(g)
b)CaC2(s)+2H2O(l)==>Ca(OH)2(aq)+C2H2(g)
c)H2SO4(aq)+Ca(HCO3)2(s)==>CaSO4(aq)+2H2O(l)
d)FeS(s)+2HCl(aq)=>FeCl2(aq)+H2S(g)

You have to "test" all the reactions to see if they're a redox. I'm assuming you know the rules for oxidation numbers. I'll show you how to test for oxidation in the first equation and then you should be able to do the rest yourself.

For a):
    +4  -2            +1 -2                         0
6 C     O₂       + 6H₂O -> C₆H₁₂O₆ + 6O₂

O.N for Carbon in glucose = 6x+12(1) + 6(-2) = 0
x = 0

Carbon's O.N has decreased from +4 to 0 and therefore it has been reduced, oxygen's O.N has increased from -2 to 0, indicating that this is a redox reaction.