Please help me verify:
The following reactions are involved in the formation of acid rain. Use oxidation numbers to identify which of these reactions are REDOX reactions.
a. 2SO2(g) + O2(g) �� 2SO2(g)
-2 -2 0 -2 -2
No change - not REDOX reacton
b. 3NO2(g) + H2O(l) �� 2HNO3(aq) + NO(g)
-3 -2 +1 -2 +1-3-2 -3-2
Nitrogen and Oxygen are reduced
REDOX reaction has occured
c. SO2(g) + H2O(l) �� H2SO3(aq)
-2-2 +1-2 +1-2-2
Oxygen is reduced
REDOX reaction has occured
Please check...
ps. why would they make a rule for hydrogen in most compounds being +1 when is it not? Same with oxygen being -2.
You still are having trouble with oxidation numbers.
a is not balanced. I think you meant to write
2SO2 + O2 ==> 2SO3
And that is a REDOX equation. S changes from +4 to +6; oxygen changes from zero (the O2 is zero while the O in SO2 is unchanged) to -2 in SO3.
b. You are correct that this is a redox equation but not for the right reasons. N changes from +4 in NO2 on the left to +5 in HNO3 on the right and +2 in NO on the right. Therefore, N in NO2 on the left undergoes both oxidation and reduction. You note that oxygen changes but it doesn't. The oxidation number on the left (in H2O) is -2 and on the right it is -2 in HNO3 and -2 in NO.
c. SO2(g) + H2O(l) �� H2SO3(aq)
S in SO2 is +4 and in H2SO3 is 4. No change. O in SO2 is -2 and O in H2O is -2. ON the right, O in H2SO3 is -2. No change so this is not a redox equation.
Re: your P.S. Because in MOST compounds, H is +1 and in MOST compounds O is -2. H is something other than +1 ONLY in the hydrides (LiH, NaH, KH, CaH2, etc where it is -1). O is other than -2 only in the peroxides (Na2O2, H2O2, K2O2, BaO2, etc where it is -1) AND in the superoxides (KO2, etc where it is -1/2).
Hi yes sorry the arrows didn't work out when I copied the question.
For the following in your answer
2SO2 + O2 ==> 2SO3
And that is a REDOX equation. S changes from +4 to +6; oxygen changes from zero (the O2 is zero while the O in SO2 is unchanged) to -2 in SO3.
Why is S +4? Doesn't S gain 2 electrons hence -2?
I'm using periodic table and S is in group 6A/16 . I thought 6A = 6
This is corrispondence course so all I have done is based on book explanation and my research so I'm not entirely confident on my periodic table use, maybe that is why I'm getting this wrong.
Hi again - was just comparing part c with your notes and I have an extra Oxygen on left side that right side doesn't have?? Perhaps your mistaken and oxygen is reduced?
Please disregard my 2 comments after. I finally had my Eureka moment and figured this all out. Thanks to your help and researching a bit more I feel I understand this now. Your efforts in helping me were not wasted lol. Thanks again!
Let's go through the reactions one by one and determine if they are REDOX reactions by examining the changes in oxidation numbers for each element involved.
a. 2SO2(g) + O2(g) 🡪 2SO3(g)
In this reaction, the oxidation numbers of sulfur and oxygen do not change. Since there are no changes in oxidation numbers, this is not a REDOX reaction.
b. 3NO2(g) + H2O(l) 🡪 2HNO3(aq) + NO(g)
In this reaction, the oxidation number of nitrogen decreases from +3 in NO2 to +1 in HNO3, while the oxidation number of oxygen increases from -2 in H2O to -2 in HNO3. Additionally, NO is formed with an oxidation number of +2. Based on these changes in oxidation numbers, we can conclude that this is a REDOX reaction.
c. SO2(g) + H2O(l) 🡪 H2SO3(aq)
In this reaction, the oxidation number of oxygen decreases from 0 in O2 (in H2O) to -2 in H2SO3. As a result, this is a REDOX reaction.
So, you are correct in your identification of b. and c. as REDOX reactions.
Now, regarding your question about the oxidation numbers of hydrogen and oxygen in most compounds, there are indeed general rules for assigning oxidation numbers. However, it is important to note that there are exceptions to these rules based on the specific compound or context.
The rule for hydrogen is that it is typically assigned an oxidation number of +1 in compounds, such as H2O or HCl. However, there are cases where hydrogen can have a different oxidation number, for example, in metal hydrides where it has an oxidation number of -1.
Similarly, oxygen is typically assigned an oxidation number of -2 in compounds, such as H2O or CO2. But there are exceptions, such as in peroxides (e.g., H2O2) where oxygen has an oxidation number of -1, or in compounds like OF2, where oxygen has a positive oxidation number.
So, while there are general rules for assigning oxidation numbers, it is always important to consider the specific compound and any exceptions to those rules.