Introduction

In this experiment, you will study the effect of changing temperature on the amount of solute that will dissolve in a given amount of water. Water solubility is an important physical property in chemistry, and is often expressed as the mass of solute that dissolves in 100 g of water at a certain temperature. In this experiment, you will completely dissolve different quantities of potassium nitrate, KNO₃, in the same volume of water at a high temperature. As each solution cools, you will monitor temperature using a computer-interfaced Temperature Probe and observe the precise instant that solid crystals start to form. At this moment, the solution is saturated and contains the maximum amount of solute at that temperature. Thus each data pair consists of a solubility value (g of solute per 100 g H₂O) and a corresponding temperature. A graph of the temperature-solubility data, known as a solubility curve, will be plotted using the computer.

Objectives