How would you start these problems?
...I suppose this is a continuation from this post: (replace the numbers with id=1395127807)
But, I have yet figured out the ΔH ̊ and ΔS ̊ .
But once that is figured out, how would I start problem #1?
Also, for problem #2, could someone please explain to me why? Is it because Ca(OH)2 is not soluble in water and can only be collected through titration?
1. Calculate the molar solubility of Ca(OH)2at 50 ̊C using your experimental values of ΔH ̊ and ΔS ̊ . This value is not the average value of the molar solubilities at 0 ̊C and 100 ̊C solubilities? Why not?
2. Why is it necessary to filter the solution before titrating? How would having a small amount of Ca(OH)2(s) in the titration flask affect your results?
To start solving these problems, you need to understand the concepts of molar solubility, enthalpy change (ΔH°), entropy change (ΔS°), solubility at different temperatures, and the process of filtration before titration.
For problem #1, if you have already determined the values of ΔH° and ΔS° experimentally, you can use them to calculate the molar solubility of Ca(OH)2 at 50°C. The molar solubility can be determined using the equation: ΔG° = ΔH° - TΔS°, where ΔG° represents the standard Gibbs free energy change for the process. By rearranging the equation, you can solve for the molar solubility of Ca(OH)2 at 50°C.
However, it is important to note that the molar solubility at 50°C may not be equal to the average value of the molar solubilities at 0°C and 100°C. This is because the solubility of a compound is influenced by temperature, and the solubility values at different temperatures may follow different trends. Therefore, it is necessary to calculate the molar solubility specifically at 50°C.
For problem #2, filtration before titration is necessary to remove any solid Ca(OH)2 particles from the solution. The reason for this is that during titration, an acid (usually HCl) is added to the solution, which reacts with Ca(OH)2 to form a soluble salt (usually CaCl2) and water. If any solid Ca(OH)2 particles are present in the solution during titration, they can interfere with the accuracy of the titration results.
Having a small amount of Ca(OH)2(s) in the titration flask would affect the results of the titration because it would lead to incorrect measurements. The solid particles can cause inaccuracies in the volume measurements, alter the reaction stoichiometry, and affect the indicator's color change during the titration. Therefore, it is essential to filter the solution before titration to obtain accurate and reliable results.