# Calculating Equilibrium Concentrations of H+ and HSO3 in SO2-Rainwater Reaction

• gunnar
In summary, the conversation was about calculating the concentration of SO2 in a certain region given the equilibrium constant for the reaction of SO2 and rainwater. The participants discussed how to handle HSO3 in the equation and how to find the pressure of SO2 using the data provided. They eventually resolved the issue by converting from ppm by volume scale to concentration and taking the negative log of the result.
gunnar
Hi, can someone please give me a hint to this problem?

The concentration of SO2 in the troposphere over a certain region is 0,16 ppm by volume. The gas dissolves in rainwater as follows:
SO2(g) + H2O(l) >> H+(aq) + HSO-3(aq)
Given that the equilibrium constant for the preceding reaction is 1.3e-2. We assume the reaction does not affect the partial pressure of SO2.

I've tried everything I can think of. I am not sure how to handle HSO3 in the equation, is it the same conc. as H+?

In trouble

Assuming the amount of $$H^+$$ and $$HSO_3^-$$ was insignificant compared to after the reaction, it's safe to treat the two reactants as having the same concentration.

OK. I treated them as to be the same conc. But how can I get the pressure of SO2?

You need the concentration of S02, try finding it from the data

$$Ka=[x][x]/[(concentration~of~S02)-x]$$, solve for x

$$pH=-log[x]$$

I solved for x and still don't get it right. I got the pressure of SO2 to be 5,6e-5 atm from the information I got. Used P=nRT/V
Since SO2 is 0,16 ppm it must be 0,16 mg in one liter I assume STP conditions. And I got the MW of SO2 to be 64,07 g/mol
Am I wrong?

why are you using pressure, it's supposed to be in concentration, I'm pretty sure that you can directly convert to concentration from ppm by volume scale. Don't forget to take the negative log of x, this will be your answer.

## 1. What is the acceptable pH range for rainwater?

The acceptable pH range for rainwater is 5.6-6.5. This range is considered to be slightly acidic, as rainwater naturally absorbs carbon dioxide from the atmosphere, which forms carbonic acid and lowers the pH.

## 2. Can rainwater with a high pH be harmful?

Yes, rainwater with a high pH (above 7) can be harmful as it may indicate the presence of pollutants or chemicals. This can be damaging to plants, animals, and the environment. It is important to monitor and maintain the pH of rainwater to ensure its safety.

## 3. What factors can affect the pH of rainwater?

Several factors can affect the pH of rainwater, including air pollution, volcanic activity, and agricultural practices. Human activities such as burning fossil fuels and using chemicals can also contribute to changes in rainwater pH.

## 4. How can I test the pH of rainwater?

You can test the pH of rainwater using a pH testing kit, which can be purchased at most hardware or gardening stores. Follow the instructions provided with the kit to obtain an accurate reading.

## 5. How can I adjust the pH of rainwater?

If the pH of rainwater is too high, it can be adjusted by adding materials such as peat moss, pine needles, or vinegar to lower the pH. If the pH is too low, adding agricultural lime or wood ash can help raise the pH. It is important to carefully follow instructions and monitor the pH levels when adjusting rainwater.

• Biology and Chemistry Homework Help
Replies
7
Views
13K
• Biology and Chemistry Homework Help
Replies
4
Views
3K
• Biology and Chemistry Homework Help
Replies
4
Views
7K
• Biology and Chemistry Homework Help
Replies
4
Views
7K
• Biology and Chemistry Homework Help
Replies
10
Views
8K
• Chemistry
Replies
20
Views
164K