Chemistry, Ch.4, End Qs, #4 from passage

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Noor0110
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Joined: Wed Mar 11, 2020 3:36 pm

Chemistry, Ch.4, End Qs, #4 from passage

Post by Noor0110 » Mon Mar 16, 2020 10:00 pm

Hi,

The answer explanation for this Q is below. More or else, the Q asks for the product of SO2 + H2O. I have no idea how to know what the product will be. Ofcourse, I can guess it must be some kind of acid with Sulfur, but how do I know it's sulfuric acid (H2SO4) or sulfurous acid (H2SO3)?? Also, is it important to know the names of these compounds for the test??? Yes? So, would it be worth it for me to spend time memorizing these polyatomic ions/names?? PLEASE HELP ME SOMEONE.

ANSWER EXPLANATION::

B is correct. Acid rain was mentioned in paragraph 1. We are told sulfur dioxide is the major oxide of sulfur initially formed when coal is burned, and reacts with water to form acid rain. The reaction between sulfur dioxide (SO2) and water H2O), produces H2SO3, known as sulfurous acid, because the anion is sulfite.


A, C, D: Sulfuric acid is H2SO4, which has the sulfate anion. Sulfuric acid is the product of the reaction between water and sulfur trioxide. Hydrosulfuric acid exists as H2S in aqueous solution, with the anion being sulfide, S2-. Sulfonic acid is a class of organic acids with the general formula of RSO3H.
NS_Tutor_Mathias
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Re: Chemistry, Ch.4, End Qs, #4 from passage

Post by NS_Tutor_Mathias » Tue Mar 17, 2020 12:17 am

This is a tough question, but doable as long as you trust that you've been given the necessary information.

We know that this reaction takes place in rain water, and rain water pre-acidification can be expected to have a pH near 7. Now we know our reactant and solvent, and we can begin to write a balanced reaction:

SO2 + H2O --> ???

Realizing that the same atoms must be present on both sides of our chemical equation, we can deduce that this only works out as the following:

SO2 + H2O --> H2SO3

As if the ion formed were sulfate, we would end up with excess hydrogen on the right side of our equation or otherwise remain unable to balance. That is really all there is to it.

The names of polyatomic ions and their respective acids are totally fair material and you should know those by heart. They will rarely be tested as directly as here, but they are very likely to show up in some form.
Noor0110
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Joined: Wed Mar 11, 2020 3:36 pm

Re: Chemistry, Ch.4, End Qs, #4 from passage

Post by Noor0110 » Thu Mar 19, 2020 9:55 pm

Thank You! It makes sense now =)
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