Solubility of KCl

Introduction:

In this lab the student will find the solubility of potassium chloride in water at room temperature. I only give the students the Purpose of this lab. They are responsible for coming up with a valid Procedure, identifying and collecting requires data, calculating the solubility, and writing a conclusion. Be patient! This is the first time most of the students have had to think about a lab.

Estimated time to complete lab:

I will normally give the students two 55-60 minute periods to plan and complete this lab activity (I expect a minimum of 2 trials – preferably 3 trials)

Equipment Required:

Distilled/de-ionized water
Solid KCl
Glass stirring rods
Scoopula
Graduated cylinders
Beakers
Mortar and pestle
Evaporating dish
Filter paper and funnel
Bunsen burner
Iron ring and stand
Wire gauss
Drying oven

The actual list may include some, all, or more of what is listed above. Your true requirements will depend on your students.

Safety Concerns:

Wear safety glasses at ALL times during the lab.
Students will be working with Bunsen burners, so all of the usual precautions for working with Bunsen burners should be followed.
Students can not leave an operating Bunsen burner unattended.
Remind the students that the glassware, iron ring, and wire gauss will be HOT for a long time after the burner is shut off. Burnt fingers are common among impatient students.
Check all glassware for cracks/defects before heating.
Be sure to wash hands after completing the lab.

Clean Up Concerns:

Be sure that all equipment is cool before putting it away. The potassium chloride solution produced can safely be washed down the sink with running water.

What Can Go Wrong:

The students will initially be confused and frustrated and will wait for you to give them the procedure- don’t do it.
The “Monkey See, Monkey Do” factor will come heavily into play during this lab. Students will see another group doing something and will blindly follow that they are doing with no idea why. When I see this happening I quietly ask the followers WHAT they are doing and WHY. If they can answer these questions successfully, I allow them to continue. If they can not, I tell them to think about what they are going to do and then let me know.
Some groups will start with large volumes of water (50mL plus) and may not even finish one trial the first day.

Student Lab Sheet as a Word Document:

There is no document to download for this lab as it is student generated.

Click here to return to the Lab Manual Contents page.