Study of Solubility Equilibrium of Khc4H4O6
Name: Beatrice Yeo Zi Hui Lab Group: B1
Fume Hood Number: B4 Matriculation Number: A0102491R
Email Address: a0102491@nus.edu.sg Date: 1st February 2013
CM1191
Experiment 1: Study of Solubility Equilibrium
1. Abstract
The aim of this experiment is to determine the relationship between the solubility of potassium hydrogen tartrate (KHC4H4O6) and temperature. Titrate a known concentration of NaOH against a saturated solution of KHC4H4O6 at different temperatures to obtain the concentrations of KHC4H4O6, and hence the solubility product constant of KHC4H4O6 at various temperatures. It was found that the solubility product constant of KHC4H4O6 is higher at higher temperatures, thus it can be concluded that the salt is more soluble when temperature increases. 2. Introduction
The aim of this experiment is to determine how solubility of a salt is affected by temperature differences. In this experiment, KHC4H4O6, a sparingly soluble salt is used. The dissociation reaction is
KHC4H4O6 (s) ⇌ K+ (aq) + HC4H4O6- (aq)
and the solubility product constant, Ksp, expression can be written as
Ksp = [K+][HC4H4O6-]
As KHC4H4O6 dissociates, it gives the same amount of HC4H4O6- and K+ ions, so the Ksp expression may be rewritten as the square of [HC4H4O6-], i.e.
Ksp = [HC4H4O6-]2
The hydrogen tartrate ion, HC4H4O6-, acts as a weak monoprotic acid. The concentration of HC4H4O6- can be determined by titrating it against a standardised strong base.
HC4H4O6-(aq) + OH-(aq) → C4H4O6-2(aq) + H2O(l)
In this experiment, NaOH is used. As the HC4H4O6- and OH- ions will react in a 1:1 molar ratio, the concentration of HC4H4O6- can be obtained from calculating the moles of OH- used. From here, the Ksp values can be obtained by repeating the experiment at various temperatures.
The Ksp and temperature relationship may be shown through the Jacobus Henricus van’t Hoff equation. The equation is derived from the Gibbs free energy definition (1) and the
Fume Hood Number: B4 Matriculation Number: A0102491R
Email Address: a0102491@nus.edu.sg Date: 1st February 2013
CM1191
Experiment 1: Study of Solubility Equilibrium
1. Abstract
The aim of this experiment is to determine the relationship between the solubility of potassium hydrogen tartrate (KHC4H4O6) and temperature. Titrate a known concentration of NaOH against a saturated solution of KHC4H4O6 at different temperatures to obtain the concentrations of KHC4H4O6, and hence the solubility product constant of KHC4H4O6 at various temperatures. It was found that the solubility product constant of KHC4H4O6 is higher at higher temperatures, thus it can be concluded that the salt is more soluble when temperature increases. 2. Introduction
The aim of this experiment is to determine how solubility of a salt is affected by temperature differences. In this experiment, KHC4H4O6, a sparingly soluble salt is used. The dissociation reaction is
KHC4H4O6 (s) ⇌ K+ (aq) + HC4H4O6- (aq)
and the solubility product constant, Ksp, expression can be written as
Ksp = [K+][HC4H4O6-]
As KHC4H4O6 dissociates, it gives the same amount of HC4H4O6- and K+ ions, so the Ksp expression may be rewritten as the square of [HC4H4O6-], i.e.
Ksp = [HC4H4O6-]2
The hydrogen tartrate ion, HC4H4O6-, acts as a weak monoprotic acid. The concentration of HC4H4O6- can be determined by titrating it against a standardised strong base.
HC4H4O6-(aq) + OH-(aq) → C4H4O6-2(aq) + H2O(l)
In this experiment, NaOH is used. As the HC4H4O6- and OH- ions will react in a 1:1 molar ratio, the concentration of HC4H4O6- can be obtained from calculating the moles of OH- used. From here, the Ksp values can be obtained by repeating the experiment at various temperatures.
The Ksp and temperature relationship may be shown through the Jacobus Henricus van’t Hoff equation. The equation is derived from the Gibbs free energy definition (1) and the
References: [1] Solubility reference values available from Paula Sousa and Ana M. C. Lopes, 2001: Solubilities of Potassium Hydrogen Tartrate and Potassium Chloride in Water + Ethanol Mixtures. J. Chem. Eng. Data, 2001, 46 (6), pp 1362–1364 [2] Oxford Dictionaries