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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: khaosabre on February 10, 2020, 10:59:40 AM

Title: Question about solubility
Post by: khaosabre on February 10, 2020, 10:59:40 AM

Hello, I've been stuck on a question for a while now, and I would like to have someone else look at it.
The question is: "Sodium carbonate is added in small quantities to a solution containing Ni²⁺ ions with a molar concentration of 0.1 and Cu²⁺ ions with a molar concentration of 0.1. Calculate the concentration of the first ion which starts to precipitate when the second ion starts to precipitate as well. Ksp(NiCO₃) = 1.4x10^-7, Ksp (CuCO₃) = 2.5x10^-10".
The way I've solved this particular question has given me an unsual answer, but basically what I've done was to calculate the concentration of the carbonate ion needed in order to make CuCO₃ precepitate and then use the same concentration to calculate the concentration of Ni²⁺ions as requested. The result I've got is 56 M.
Can someone please tell me if I answered correctly or if I did something wrong? The result just doesn't seem right and I can't seem to find an answer on any of my Chemistry books.
Thank you very much.

Title: Re: Question about solubility
Post by: Borek on February 10, 2020, 11:40:45 AM

Yes, the result looks off and definitely something is wrong.

Show your calculations and we will help you find the mistake.