Discussion Overview
The discussion revolves around calculating the pH of rainwater in equilibrium with sulfur dioxide (SO2) in a polluted air mass, specifically at a concentration of 1 ppm. The conversation includes aspects of chemistry such as Henry's law, acid dissociation, and the stoichiometry of the reactions involved.
Discussion Character
- Homework-related
- Mathematical reasoning
- Technical explanation
Main Points Raised
- One participant expresses confusion about how to set up the equilibrium expression and mentions having two unknowns in their calculations.
- Another participant suggests applying Henry's law to calculate the concentration of the acid and notes that only the first dissociation constant (Ka1) is provided, implying that the diprotic nature of the acid can be ignored for this problem.
- A participant calculates the concentration of dissolved SO2 using Henry's law and questions how to proceed to find the concentration of H2SO3.
- There is a discussion about whether the pressure of water at 25°C is necessary for the calculations, with one participant suggesting it may not be relevant if the air is not specified as dry.
- One participant proposes that the total concentration of acid can be assumed to be that of dissolved SO2.
- Another participant questions the calculation of H2SO3 concentration and expresses doubt about the results obtained from the quadratic equation used to find the concentration of H+. They note a discrepancy with the reported Ka value.
- A later reply suggests that a pH of 6 appears reasonable based on the calculations presented.
Areas of Agreement / Disagreement
Participants express varying levels of understanding and approaches to the problem, with no consensus reached on the correct method or final answer. Disagreements arise regarding the relevance of certain calculations and assumptions made about the system.
Contextual Notes
Participants mention the need to consider the stoichiometry of the reactions and the assumptions made about the concentrations of species involved, particularly regarding the relationship between H2SO3, HSO3-, and H+.