Study of Solubility Equilibrium of Potassium Hydrogen Tartrate
Study of Solubility Equilibrium of Potassium Hydrogen Tartrate
Wang Haina
1. Aim 1. To determine the solubility of potassium hydrogen tartrate (KHT) at various temperatures from 10°C to 50 °C, and determine the corresponding Ksp at these temperatures. 2. To obtain the changes in enthalpy and entropy of the dissolution of KHT from the dependence of Ksp on temperature.
2. Results and discussion
2.1 Collection of data
A portion of KHT (1 to 1.5 g) was added into about 100 mL of deionised water to prepare a saturated KHT solution. Several such solutions were prepared at various temperatures between 10°C and 50 °C, and filtrated into dry 250-mL conical flasks. For solutions made above or below the room temperature, their temperatures dropped or increased during filtrations. For each solution, two portion of 25.00±0.03 mL were pipetted into two 250-mL conical flasks and titrated with 0.07274 M of NaOH solution respectively with phenolphthalein as indicator. The temperatures of the KHT solutions and the corresponding volumes of NaOH solution used for titration are shown in Table 1. For each row, the temperature is the average of the temperatures immediately before and after the filtration, and the volume is the average of the two titrations.
Table 1 The temperatures of saturated KHT solutions and the corresponding volumes of NaOH solution used for titration. Temperature (±0.5 °C) | Vol. of NaOH soln (±0.05 mL) | 12.5 | 8.82 | 17.5 | 9.05 | 19.5 | 10.35 | 23.0 | 10.15 | 23.0 | 11.13 | 37.5 | 15.50 | 42.5 | 14.40 | 48.5 | 18.95 |
It is noted that though the general trend is that the volume of NaOH increases with increasing temperature, there are some inconsistencies in this table. For example, the two volumes of NaOH at 23°C (obtained respectively by my partner and me) are different, and the volume at 42.5°C is lower than that at 37.5°C, contrary to the general trend. These will be discussed in the later subsection of error analysis, and
Wang Haina
1. Aim 1. To determine the solubility of potassium hydrogen tartrate (KHT) at various temperatures from 10°C to 50 °C, and determine the corresponding Ksp at these temperatures. 2. To obtain the changes in enthalpy and entropy of the dissolution of KHT from the dependence of Ksp on temperature.
2. Results and discussion
2.1 Collection of data
A portion of KHT (1 to 1.5 g) was added into about 100 mL of deionised water to prepare a saturated KHT solution. Several such solutions were prepared at various temperatures between 10°C and 50 °C, and filtrated into dry 250-mL conical flasks. For solutions made above or below the room temperature, their temperatures dropped or increased during filtrations. For each solution, two portion of 25.00±0.03 mL were pipetted into two 250-mL conical flasks and titrated with 0.07274 M of NaOH solution respectively with phenolphthalein as indicator. The temperatures of the KHT solutions and the corresponding volumes of NaOH solution used for titration are shown in Table 1. For each row, the temperature is the average of the temperatures immediately before and after the filtration, and the volume is the average of the two titrations.
Table 1 The temperatures of saturated KHT solutions and the corresponding volumes of NaOH solution used for titration. Temperature (±0.5 °C) | Vol. of NaOH soln (±0.05 mL) | 12.5 | 8.82 | 17.5 | 9.05 | 19.5 | 10.35 | 23.0 | 10.15 | 23.0 | 11.13 | 37.5 | 15.50 | 42.5 | 14.40 | 48.5 | 18.95 |
It is noted that though the general trend is that the volume of NaOH increases with increasing temperature, there are some inconsistencies in this table. For example, the two volumes of NaOH at 23°C (obtained respectively by my partner and me) are different, and the volume at 42.5°C is lower than that at 37.5°C, contrary to the general trend. These will be discussed in the later subsection of error analysis, and
References: 1. Study of solubility equilibrium. http://www.bignerds.com/papers/77914/Study-Of-Solubility-Equilibrium/ (accessed October 14, 2014). 2. Solubility And K dependence on temperature. http://www.ukessays.com/essays/biology/solubility-and-k-dependence-on-temperature-biology-essay.php (accessed October 14, 2014). Appendix Data sheet. (See attached paper.) This experiment was done with collaboration of Wang Zhuliang.