Calculate the minimum concentration of Mg²⁺ that must be added to 0.10 M NaF in order to initiate a precipitate of magnesium fluoride.[K_sp(MgF₂)= 6.9 × 10^-9] rev: 08_14_2014_QC_52437

Question

Quizplus · Accepted Answer

The balanced chemical equation for the precipitation reaction is:

MgS1U1P12+S1S1P0 + 2NaF → MgFS1U1B12S1U1B0 + Na2S1U1B0

From the equation, we can see that one mole of MgS1U1P12+S1S1P0 reacts with two moles of NaF to form one mole of MgFS1U1B12S1U1B0.

Therefore, the number of moles of MgS1U1P12+S1S1P0 required to react with all the NaF present in the solution is:

(2 mol NaF / 1 mol MgS1U1P12+S1S1P0) x (0.10 mol NaF) = 0.20 mol MgS1U1P12+S1S1P0

The volume of the solution is not given, so we cannot calculate the exact concentration. However, we can calculate the minimum concentration of MgS1U1P12+S1S1P0 needed to provide 0.20 mol:

minimum concentration = (0.20 mol) / (1 L) = 0.20 M

Since this value is larger than all the given answer choices except E, the correct answer is E, 6.9 × 10S1U1P1-7S1S1P0 M.

Calculate the Minimum Concentration of Mg2+ That Must Be Added

Calculate the Minimum Concentration of Mg²⁺ That Must Be Added