atq experiment #5 chem 26.1

Chua, John Joseph R.2014-30936

Calculations

Concentration of the standardized HCl solution

Experimental Ksp and Molar Solubility based on Procedure C

Solubility of Ca(OH)2 in Procedure D

Ionic strength of the different KCl solutions in Procedure EIonic strength, for easier calculation in this ATQ, is represented by the function f(x,y) wherein x is the concentration of Ca2+ ions and y is the concentration of OH- ions. (Data tabulated in Excel, attached herewith)

Solubility of Ca(OH)2 in Procedure E (Data tabulated in Excel, attached herewith)

ATQ 1. Write the net ionic reaction for the precipitation of Ca(OH)2 and give the Ksp expression of the reaction.a. is the net ionic reaction for the precipitation of Ca(OH)2 and the Ksp expression is . 2. What is the working equation for the determination of the [Ca2+] in the saturated solution of Ca(OH)2?a. 3. Write the Ksp of Ca(OH)2 in terms of its:a. Molar solubilityi.

b. [OH-]i.

c. [Ca2+]i.

4. Discuss the effects of common ion and increasing ionic strength on the solubility of the Ca(OH)2 precipitate. Do they coincide with theoretical effects? Explain.a. Theoretically, the addition of a common ion decreases the solubility of Ca(OH)2 because there is addition of Ca2+ ion which, due to the Le Chateliers Priniciple, directs the reaction to the formation of precipitate. In our data, the solubility increased; this may be brought about by random error which is made by wrong measurement of molarity, excessive titration, and contaminated glassware, among others. Since Ionic strength is the measure of ion concentration, higher values means higher solubility. The results have coincided with the theoretical ones in ionic strength.5. What are the possible sources of errors and their effect on the calculated parameters? Rationalize.a. Errors in standardization can cause a large error on all calculations as it is in the concentration of the titrant everything is based. The assumption of the Ksp at 25oC also increases the error in calculations, especially the relative error itself because the experiment is not exposed in the said temperature.

Referenceshttp://www.titrations.info/acid-base-titration-sodium-hydroxide-and-carbonatehttp://www.chemguide.co.uk/physical/acidbaseeqia/phcurves.html#top

Determination of Ksp and Solubility of Ca(OH)2

Trial 1Trial 2Trial 3

Filtrate, L0.050.050.05

HCl, L0.02270.02190.022

[OH]0.0526640.0508080.05104

[Ca]0.0263320.0254040.02552

s0.0263320.0254040.02552

Ksp7.30317E-056.55792E-056.64817E-05

s, X bar0.025752

Ksp, X bar6.83114E-05

Ksp, Theo.0.0000065

% Error950.9438806

Effect of Common Ions on the Solubility of Ca(OH)2


Filtrate, L0.050.050.05

HCl, L0.0250.02390.0232

[OH]0.0580.0554480.053824

[Ca]0.0290.0277240.026912

s0.0290.0277240.026912

s, X bar0.027878667

Ksp, X bar8.66714E-05

Solubility of Ca(OH)2 in 0.010 M KCl


Filtrate, L0.050.050.05

HCl, L0.0230.02620.0232

[OH]0.053360.0607840.053824

[Ca]0.026680.0303920.026912

s0.026680.0303920.026912

Ksp7.59657E-050.0001122897.79647E-05

s, X bar0.027994667



Filtrate, L0.050.050.05

HCl, L0.02550.024450.0243

[OH]0.059160.0567240.056376

[Ca]0.029580.0283620.028188

s0.029580.0283620.028188

Ksp0.0001035279.12579E-058.95886E-05

s, X bar0.02871



Filtrate, L0.050.050.05

HCl, L0.02640.02590.0255

[OH]0.0612480.0600880.05916

[Ca]0.0306240.0300440.02958

s0.0306240.0300440.02958

Ksp0.000114880.0001084760.000103527

s, X bar0.030082667



Filtrate, L0.050.050.05

HCl, L0.02840.02820.028

[OH]0.0658880.0654240.06496

[Ca]0.0329440.0327120.03248

s0.0329440.0327120.03248

Ksp0.0001430170.0001400170.000137059

s, X bar0.032712



Filtrate, L0.050.050.05

HCl, L0.03030.02980.0294

[OH]0.0702960.0691360.068208

[Ca]0.0351480.0345680.034104

s0.0351480.0345680.034104

Ksp0.0001736850.0001652280.000158663

s, X bar0.034606667

[KCl]SolubilityIonic Strength

0.010.0279946670.093984

0.050.028710.13613

0.10.0300826670.190248

0.250.0327120.348136

0.50.0346066670.60382

atq experiment #5 chem 26.1

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