Temperature and Ksp Lab

Purpose

(Summarize in lab book)

The purpose is to determine how temperature affects the Solubility Product Constant values.

Procedure

(Summarize in lab book)

1. Everyone in the room will measure out a different amount of potassium nitrate to place into 20 mL of water. See the chart below to determine the amount of potassium nitrate you need to weigh out.

1. Measure out 20 mL of water and place it into the test tube with the potassium nitrate.

2. Place it into a water bath to heat until it all dissolves. You can use the temperature probe to stir the solution to help it to dissolve.

3. After it all dissolves, remove it from the water bath and allow it to cool.

4. While it is cooling you have a few jobs. (1) Stir the solution every minute. (2) The temperature when the solid first reforms is the temperature at which your solution reaches equilibrium. RECORD THIS TEMPERATURE and share it on the board. (3) Complete step 6 while you are waiting for it to reform.

5. Usually when we are dealing with Ksp you add a very very small amount of solute into the water, therefore it has no affect on the total volume of the solution. Today we are adding a large amount of solute to the water, so it will affect the total volume of the solution. We need to find that total volume, but we can not pour the contents out of the test tube because we are watching it to see at what temperature a solid reforms in order to find the equilibrium point. So to find the total volume of the solution, fill up a different test tube with water to the same level as your test tube (hold them next to each other). Use this new test tube to determine the volume of your solution. Share your solution volume on the board.

Data

Copy data table of all the groups information into your lab book.

Calculations

Calculate the ksp for every temperature. Be sure to show your work clearly and neatly for the amount you measured out. You will have to do calculations for all of the amounts, but you just need to show the work for yours. In order to organize your calculations, create a data table with group number, concentration of each ion, and ksp value.

Graph

Create a graph showing temperature vs ksp value. Next to the graph remember to write the equation, graph type, and relationship.