When ionic solids dissolve, they divide to give their positive and negative ions that make up the solids. These ions become hydrates and have the same relative proportions when in solution and when solid. The more the solid dissolves, the more the ion's concentration increases. This increase and build-up allows for the reverse reaction to occur. In this phase of the reaction the ions crystallise out in order for the reaction to have a greater chance of occurring. Eventually the rate of dissolving will equal the rate of crystallisation. This is the state of saturation. This can be recognised by a constant colour or constant mass.
The solubility product constant, Ksp is given in the following example:
Through this information we were able to determine the Ksp value for his experiment, which ranges between 3.20x10^-8 and 1.35x10^-8, or between test tubes 4 and 5. We may further determine that lead iodide is less soluble in a solution of .1 M KI than in pure water. Adding KI would cause a shift in the equilibrium to the reactants, which would further result in the decrease of the lead's solubility. Inorder to dissolve the coating of lead iodide on the inside of a test tube, you could either decrease the amount of PB or of I in the solution. Thus causing a shift to the products, which would initiate the reaction to dissolve.
etween the ions in the saturated solution and is the maximum concentration possible without creating precipitation. In this lab, solutions of lead nitrate and potassium iodide will be mixed at a number of
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