Identify the species oxidized and the species reduced in each of these redox equations, and give the oxidation numbers of each element.
a. 3Br2 + 2Ga → 2GaBr3
b. 2HCl + Zn → ZnCl2 + H2
c. 3Mg + N2 → Mg3N2
I will do one to show you how to do the others.
First see the url below. That is an excellent tutorial on how to determine the oxidation state of an element.
www.chemteam.info/Redox/Redox.html
2HCl + Zn → ZnCl2 + H2
Read and study that url from chem team. That is an excellent explanation of how to determine the oxidation state of an element in a compound. Here is the HCl/Zn problem.
First, an element by itself is a zero oxidation state. So that tells you the Zn on the left and H2 on the right are zero.
Next, it is fairly common knowledge, at least after a little work in chemistry, that Cl is -1. If Cl is -1 then YOU KNOW that H is +1 because YOU KNOW that compounds have zero just like free elements do. On the right, we know Cl is 1- so ZnCl2 must be what. Well Zn + 2(-1) = 0; therefore, Zn must be +2. So Zn goes from zero on the left to +2 on the right. That must be a loss of 2 electrons. Next, H goes from +1 on the left (FOR EACH H to make a total of +2 to zero on the right. That is a gain of 2 electrons. How did I do that. Electrons have a -1 charge so +2 + -1(n) = 0 so n= +2 and a +2 tells me that is a GAIN of 2 electrons. For Zn to ZnCl2 that is 0 +(-n) = +2 or n =
-2 or loss of 2 electrons
What's oxidized and what's reduced. Stick with the definitions. Oxidation is the loss of electrons. Reduction is th gain of electrons. Have trouble remembering those definitions. Here are two mnemonics.
LEO the lion goes GER (GRR) which is
Loss electrons oxidation and GER is gain electrons reduction.
Another is OIL RIG
Oxidation is loss (of electrons)
Reduction is gain (of electrons)
Post your work if you would like for me to check it.