![]() ![]() I calculated this from the Ksp equation substituting the variable 'x' for the molarity of the solution and then assigning the ion concentrations appropriate values of 'x'. however I now realise that the figure of 0.163 M is actually not the molarity of Lithium Phosphate but the molarity of the ion in solution. Now I wont go into too much detail of how I calculated the Molarity of the Lithium Phosphate suffice to say I got this problem correct. Which solution has a higher lithium cation concentration? One is made by dissolving lithium carbonate ( Ksp = 8.15 x 10−4) in 100.0 mL of water until excess solid is present, while the other is prepared by dissolving lithium phosphate ( Ksp = 2.37 x 10−4) in 200.0 mL of water until excess solid is present. Īgain, two saturated aqueous solutions are prepared at 25 ✬. If I give you details of the previous problem refered to in this problem and how I calculated the molarity of the Lithium Phosphate solution being used in this precipitation reaction maybe the situation will become clearer.īelow are the details of problem 3 (the prior problem referred to) and they are as follows. I am afraid I have given you an inadequate and erroneous description of the problem I seek to understand. Doesn't your net ionic equation give you a clue? Is this correct ? If not where have I gone wrong ? Can anybody help ?Īlso note that you are going wrong because your precipitation reaction equation is not balanced. Ĭalculating it's molar mass (g/mol) and multiplying this by it's actual molarity (mol) giving the mass present of precipitate in solution after the reaction. So we now convert from moles to mass (grams) of the precipitate by. Then the molarity of Mg3(PO4)2 is also 0.163 M. ![]() Now the previously prepared saturated solution of Li3PO4 has a calculated molarity of 0.163 M so as the molar ratio of this to our saturate is 1:1 1 mole of LI3PO4 produces 1 mole of Mg3(PO4)2 (which is the precipitate). So from the reaction equation - MgCl2 + Li3PO4 -> Mg3(PO4)2 + LiCl Also the net ionic equation talked about in the problem is listed in the equations section above, but I repeat here. Note - The molarity of the prepared lithium phosphate mentioned above from a previous problem was 0.163 moles/litre (I know this is correct from the exam feedback). How many grams of the new solid precipitates? In problem #4, you wrote the net ionic equation for the reaction that results. This is my subsequent attempt to solve it after the exam (so I dont know if this attempt is correct or not) and would appreciate any input reassuring me that this, my last attempt, is correct or if wrong where I am going wrong with this type of problem.Īn aqueous solution containing excess magnesium chloride is mixed with the saturated solution of lithium phosphate prepared in problem #3. I have a problem from an exam which I passed recently, however this was one problem I got wrong and I want to understand how to solve the thing.
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