Solubility Lab

Purpose (put into lab book)

• The purpose of this lab is to create a solubility curve for an unknown substance and determine it's identity.

Hypothesis (answer in a complete sentence in lab book)

• Examine your green reference sheet with the solubility curves. Guess which compound you think the unknown is. Hint: it is a solid

Materials (read the procedure below and list at least 10 different materials you will need)

Procedure (summarize in lab book)

1. Fill a beaker with about 400mL of water and heat it on the hot plate. This will serve as a hot water bath in which we will gently be warming our solution with.

2. Weigh out your assigned amount of the unknown solute. (Each group is assigned a different amount.)

3. Using a funnel, pour the unknown solute into a test tube.

4. Measure out 20mL of water and add it to the test tube.

5. Attach your test tube to a test tube holder, and then attach the test tube holder to the ring stand.

6. Stir to dissolve as much of the solute as you can. It will not all dissolve so we will have to heat it to dissolve the rest.

7. Lower the test tube into the beaker with the hot water (hot water bath). Heat it until it all dissolves.

8. When it is all dissolved, raise it out of the hot water bath.

9. Allow it to cool. To prevent a supersaturated solution from occurring, stir it frequently.

10. Once you see a solid form, record the temperature.

11. Share this information on the board for the rest of the class.

Data (put into lab book)

Calculations (show in your lab book)

We are using only 20mL of water, instead of 100 mL like the reference sheet. In this section, show how you can figure out how much we would have been able to dissolve if we had used 100 mL of water. Show your calculations then fill your answers into that column in the data table.

Hint: Use the ratio!!!

Graph (click here to get the graph paper to graph this data by hand)

• set up the axes just like your green ref sheet

  • x-axis = temperature (0-100)

  • y-axis = mass of solute (g)/100g of water (0-150)

• graph your data

• compare this to your solubility curve to determine the unknown

Conclusion (put into lab book - your 3 paragraph conclusion)

Paragraph #1 - Purpose and what was done (details!)

Paragraph #2 - What is the identity of the unknown substance? (Provide an explanation on why you think that)

Paragraph #3 - Errors and how you would fix them.