Calculate the pH of a water sample from a playa lake in the western US that has the evaporite mineral potassium bicarbonate (KHCO3) at a concentration of 0.009 mol/kg. Assume the water is in equilibrium with the atmosphere (PCO2 = 10-3.4 bar) and the temperature is 25 ̊C. Note that the pH will be greater than 7. State any other assumptions that you make to simplify the problem. Calculate the pH using the proton condition method.