Balanced equations..done?
Is each reaction a redox reaction? For those reactions that are redox reactions, I must identify the substance being oxidized and the substance being reduced...
(a) Zn(s) + CoCl2 (aq) ---> ZnCl2 (aq) + Co(s)
(b) HI(aq) + NaOH(aq) ---> H2 O(l) + NaI(aq)
(c) AgNO3 (aq) + NaCl(aq) ---> AgCl(s) + NaNO3 (aq)
(d) 2 K(s) + Br2 (l) ---> 2 KBr(s)
You need three things:
a. What is the change in oxidations state?
b. Were electrons lost of gained.
c. the definitions: oxidation is the loss of electrons.
Reductions is the gain of electrons.
Here is a.
Zn has an oxidation state of zero on the left and +2 on the right. Loss of electrons. oxidation.
Co is +2 on the left and zero on the right. Gain of electrons. Reduction.
To determine if each reaction is a redox reaction, we need to examine the oxidation states of the elements involved.
(a) Zn(s) + CoCl2(aq) ---> ZnCl2(aq) + Co(s)
In this reaction, the oxidation state of Zn goes from 0 to +2, and the oxidation state of Co goes from +2 to 0. Therefore, this is a redox reaction. Zn is being oxidized, and Co is being reduced.
(b) HI(aq) + NaOH(aq) ---> H2O(l) + NaI(aq)
In this reaction, the oxidation state of H goes from -1 to 0, and there is no change in the oxidation state of I. Therefore, this is not a redox reaction.
(c) AgNO3(aq) + NaCl(aq) ---> AgCl(s) + NaNO3(aq)
In this reaction, the oxidation state of Ag goes from +1 to 0, and the oxidation state of Cl goes from -1 to 0. Therefore, this is a redox reaction. Ag is being reduced, and Cl is being oxidized.
(d) 2K(s) + Br2(l) ---> 2KBr(s)
In this reaction, the oxidation state of K goes from 0 to +1, and the oxidation state of Br goes from 0 to -1. Therefore, this is a redox reaction. K is being oxidized, and Br is being reduced.
To summarize:
(a) Redox reaction. Zn is oxidized, Co is reduced.
(b) Not a redox reaction.
(c) Redox reaction. Ag is reduced, Cl is oxidized.
(d) Redox reaction. K is oxidized, Br is reduced.