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Title: Solution – Construction Construction of Solubility Curve for Potassium Chlorate
Objective: To study the solubility curve for potassium chlorate.
Introduction: A substance ability to dissolve in a solvent is known as its solubility. The mass of substance that will dissolve in 100ml of water is known as its solubility in water. Through this experiment, we can observe how the change in volume of water affects the solubility of a potassium chlorate in water. As the volume of water added changes, a change in temperature of which potassium chlorate dissolves, changes too. Through this experiment, solubility curve for solid potassium chlorate in different temperature can be obtained.
Apparatus and Materials: Solid potassium chlorate, distilled water, thermometer, burette, boiling tube, hot plate, beaker, ice (if necessary)
Procedures: 3.00g of potassium chlorate was accurately weighed into a boiling tube. 10.0cm 3 of water from a burette was added and a thermometer was put into the boiling tube. The boiling tube was put into a beaker of water. The water was heated and the content in the boiling tube was stirred gently with a glass rod until the solid just dissolved completely. The boiling tube was removed from the hot water and was allowed to cool in air with constant stirring. The temperature at which the crystals start to form in the boiling tube was noted. The experiment was repeated and the temperature was noted again. The average temperature was taken as the temperature at which the solution was just saturated. 5.0cm3 of water was added from the burette, and the temperature was determined as described above. The procedure was repeated until about 40.0cm 3 of water was added.
Results and Calculations: Mass of Potassium Chlorate, KClO 3 used: 3.0435g Volume of water
Temperature at which crystals start to form (°C)
Concentration of KClO 3 in 100g of water (g / 100g water) = [(mass of KClO3 used) / (mass of water added)] x 100 Mass of water added added (cm3)
Concentration of KClO3 in 100g of water (g / 100g water)
Discussion: The performed experiment was on purpose to determine the solubility curve for potassium chlorate KClO3. In order to determine this solubility curve, the experiment was done with manipulated volumes of water. It was observed that from the manipulated values of water affected the temperature at which the crystals of potassium chlorate started to reform. From this, the
concentration of potassium chlorate in 100g of water was calculated by dividing the mass of potassium chlorate added with the mass of water added added and multiplying it by 100. Through Through this formula, the different concentrations of potassium chlorate based on the specific amount of water added from time to time was obtained. The obtained value of the concentrations were used to plot a graph of concentration of potassium chlorate against temperature. From the experiment we know that the solubility of potassium chlorate is an endothermic reaction. The size of the lattice enthalpy (endothermic) is much larger than the summation of enthalpies of hydration of the ions (exothermic). This is al so known to be a thermodynamically favourable process due to the large increase in entropy as the solution was formed.
Conclusion: The solubility curve of the potassium chlorate was successfully studied and also known that the solubility of potassium chlorate is an endothermic process.
References Kessel, Hans Van and Frank Jenkins , 2002. Nelson Chemistry 12. 12th ed. s.l.:Nelson Education Limited.