Question

How many of the following are oxidation-reduction reactions? And which ones?
NaOH + HCl → NaCl + H2O
Cu + 2AgNO3 →2Ag + Cu(NO3)2
Mg(OH)2 → MgO + H2O
N2 + 3H2 → 2NH3

Answer 1

do you know how to assign oxidation states to each element?

Answer 2

um not relly

Answer 3

r u till there?

Answer 4

yeah sorry i was doing another question.

okay, theres a few rules to follow: hydrogen is always +1, oxygen is always -2, elements in the first period are always +1, elements in the 7th period (halogens) are always (or almost) -1.

ill do the first you try the others:

(+1)(-2)( +1) (+1)(-1) (+1) (-1) (+1) (-2)
Na O H + H Cl -> Na Cl + H2 O

i started with Oxygens and hydrogens first, then assigned the rest to the other element in each compound. you're basically trying to make the charges add up to zero because the compounds are neutral. if you had something with a negative charge like OH- then you'd have -2 for the O and +1 for the H.. which add up to-1 which is the charge on the compound.

Answer 5

with this information you can find out if there was an exchange of electrons, which is what redox reactions (reduction-oxidation are.

Answer 6

i.e. if the same element has different oxidation states on opposite sides of the reaction.

Answer 7

i see. what about say the compound had a transition metal. How can u determine it's oxidation state?

Answer 8

And the ones from groups 3,4,5,6?

Answer 9

thats when you use what you know to find out, basically by process of elimination.
(+3)(-2)
eg. Mn2O3 oxygen is -2 so Mn has to be +3

but transition metals can have different oxidation states
(+2)(-2)
eg Mn O

Answer 10

ohhh ok i get it!. I'll try the rest myself.

Answer 11

thanks so much for a thorough explntion.

Answer 12

yeah man no prob, when i first saw these i, too, was puzzled. but then someone explained it to me. pass it on!

Answer 13

thanks. like its so simple with practice! u r a lifesaver. i have a chem test coming up n i forgot everything i learned!

Answer 14

now if sumone asks me for help on this kind o problem i can explain it too :)

Answer 15

yeah man, everything is easy when you practice it. haha thats never good, i usually take good notes of stuff so in case i forget i can just read those over.

Answer 16

yep! exactly. if i just gave you the answer you'd learn nothing, I'm glad you're willing to work through it

Answer 17

yeah of course i don't want to make u do all the work! so thnks. All I needed was the stsep to approch the problem.

Answer 18

(Y) good stuff dude. well good luck with your studies, I'm out