Acid Mine Drainage Problem - Part 3
Our previous assumption that a river consists of pure water was obviously a simplification. Water arrives at the river after flowing over land and through the ground, and it carries some dissolved chemical species it picks up along the way.
- Predict how the buffering capacity of the river will affect both the pH of the river and the amount of Fe(OH)3 precipitated in the river. Will the pH of the river be larger or smaller than you obtained in problem 1? Will more or less Fe(OH)3 precipitate? Please explain your reasoning.
- Use the Virtual Lab to explore the chemical system and measure the pH and amount of Fe(OH)3 that precipitates when the effluent is mixed with the sample of river water.
- Did your measurements agree with your predictions from part (a)? If not, can you adjust your reasoning, for instance by including additional chemical processes, to account for the observed behaviour?
- Based on the pH you measured in part (b) calculate how much Fe(OH)3 precipitates when the acidic mine effluent is discharged into the buffered model of the river. Check your answer against the amount of precipitate you measured in part (b). How much Fe(OH)3 will be deposited outside the river each hour? How does this result compare with that obtained from the simpler, unbuffered, model in part (d) of problem 1.
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