Question

Describe Le Chatelier's principle and discuss how it can be used to understand the problem created when Flint changed their treated water source from Lake Huron to the Flint River.

Answer 1

Le Chatelier's principle:- According to this principle " A change in one of the variables that describe a system at equilibrium produces a shift in the position of the equilibrium that counteracts the effect of this change ".

according to le chatelier's principle due to change in the following conditions can change the equilibrium.

(1) changing the concentration of one of the components of the reaction

(2) changing the pressure on the system

(3) changing the temperature at which the reaction is run.

It can be used to understand the problem created when Flint changed their treated water source from Lake Huron to the Flint River

We can explain this by considering Le Châtelier’s principle, which states that a system that is shifted away from equilibrium acts to restore the equilibrium by reacting in opposition to the shift.

Lead(II) carbonate is relatively insoluble in water, but does dissolve a little, and in the process sets up this equilibrium:

PbCO₃ (s) ⇌ Pb²⁺ _(aq) + CO₃^2– _(aq)

The carbonate ions that are produced can then react with any hydrogen ions (acid) present in the water supply, according to this equation:

CO₃^2– _(aq) + H⁺ _(aq) → H₂O _(l) + CO_{2 (g)}

The lower the pH, the more hydrogen ions that are present in solution and the more the carbonate ions react. The removal of carbonate ions from the equilibrium system of lead(II) carbonate in the first equation results in an increase in the concentration of lead ions. To restore the equilibrium, the chemical reaction shifts to the right, so that additional carbonate ions (and lead ions) are produced.

To ensure that the number of lead and carbonate ions is the same on the right side of the equation, the reaction then shifts to the left and to the right a few times until a new equilibrium is reached. In this new equilibrium, the number of lead ions is the same as the number of carbonate ions, but the number of lead ions is larger than what it was during the original equilibrium (before the carbonate ions were removed), resulting in more lead ions at equilibrium than before.

THIS SAME CASE HAPPENED IN FLINT RIVER.