# Solubility Curve Essay

530 Words3 Pages
Part E – Deriving a solubility curve Aim: To be able to calculate the solubility of the compound in a certain amount of water as the temperature increases or decreases. Hypothesis: As the water increases, the solubility decreases and the substance’ saturation would get lower. And as the volume increases, the substance won’t separate to the water anymore which makes it dissolved forever without getting crystallized when the water cools down. Apparatus &amp; Method: [refer to the sheet p. 64] Result: Temperature | Volume [ml] | Solubility [g/100g] | 65 ̊ C | 5 ml | 130.44 g | 46 ̊ C | 8 ml | 81.525 g | 39 ̊ C | 11 ml | 59.29 g | 28 ̊ C | 14 ml | 46.586 g | 22 ̊ C | 17 ml | 38.36 g | 16 ̊ C | 20 ml | 32.61 g | 12 ̊ C | 23 ml | 28.35 g | 12 ̊ C | 26 ml | 25.08 g | The solubility was calculated with the formula of: Solubility=6.522gml of waterx 100 The solubility of Potassium Nitrate is directly affected by the temperature of the solution. As the temperature of the solution rises, the solubility of Potassium Nitrate increases. Each time, three more milliliter of water was added, the solution was re-heated. The more water that was present, the lower the temperature it gets. And the solution precipitates, as by means of crystallization. Discussion: a. The solubility of KNO3 at 50 ̊ C is approximately 92g/100g. b. The temperature at which the solubility of KNO3 is 80g/100g water is 44 ̊ C. c. There should be 105g of potassium nitrate to dissolve in 100g of water at 60 ̊ C. d. Using the formula of solubility, it came out that the temperature needed was 80 ̊ C to completely dissolve 20g of potassium nitrate in 25g of water. The possible errors may include: * The difference between what one person would determine as a crystal compared to another, the time between when the temperature was recorded and when the