Hello everyone. Welcome to this tutorial on Effect of Temperature on Solubility using Vlabs.
In this tutorial, we will learn About solubility of salts with temperature.
Check if solubility is exothermic or endothermic. Study the relationship between solubility and heat transfer.
To follow this tutorial, you should be familiar with ChemCollective Vlabs interface.
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Here I am using Mac OS version 10.10.5
ChemCollective Vlabs version 2.1.0 Java version 8
Here I have opened a virtual chemistry lab application window.
Go to File->Load homework option. Select Solubility and Solids.
Click on Temperature and solubility of salts option.
Click on problem description in the stockroom explorer.
Please pause the video here and read the problem description. Resume the video once you finish reading.
The problem has 3 sections. In the First section: Check solubilities of Potassium chloride and Cerium(III)sulphate with temperature.
In Second section: Observe whether dissolution of Potassium chloride and Cerium sulphate is exothermic or endothermic.
In the Third section: we have to explain the observations in section 1 and 2 based on a chemical principle.
Click on Workbench. Let us select required chemicals and apparatus for this experiment.
From the Stockroom explorer, Click on Potassium chloride, Cerius sulfate and Distilled water icons.
Click on glassware icon. Select 50 mL Graduated Cylinder.
Again click on glassware icon. Select 250 mL Erlenmeyer Flask.
We need two copies of 250 mL Erlenmeyer Flasks.
Use Duplicate option from the context menu to make the copies.
Click on select tools icon. Select Scale and Weighing boat.
We need two copies of Weighing boats. Again use Duplicate option from the context menu.
Use context menu and rename the Erlenmeyer Flasks as 1 and 2. Similarly rename the Weighing boats as 1 and 2.
Now place each set of apparatus separately on the workbench.
Drag the Distilled water tank over to graduated cylinder.
In the Transfer amount input bar, type 50. Click on Pour. Keep the Distilled water aside.
Transfer 50 mL of Distilled water to flask 1 using Precise Transfer.
Keep the graduated cylinder aside.
Drag the weighing boat 1 and place it on the scale. Click on TARE.
Drag the Potassium chloride bottle over to weighing boat 1.
Type 5 in the transfer amount input bar. Click on Pour.
Keep Potassium chloride bottle aside.
Drag the weighing boat 1 and place it on Flask 1.
In the transfer amount input bar, Type 5. Click on pour.
Keep the weighing boat aside.
In the Solution Info Panel, click on Solid radio button.
Observe, Species and grams columns.
Since all the potassium chloride is soluble in water, there is no solid Potassium chloride in the flask. Hence it indicates zero grams.
This indicates that potassium chloride is readily soluble in water.
Let us keep on adding Potassium chloride to flask 1 until undissolved Potassium chloride remains in flask 1.
Place the weighing boat 1 back on the Scale. Click on TARE.
Drag and place Potassium chloride bottle over weighing boat 1
Type 15 in the transfer amount input bar. Click on pour.
Keep Potassium chloride bottle aside.
Change the Transfer Bar to Realistic Transfer using Tools menu.
Drag and place weighing boat 1 over flask 1. Click on Pour button gradually.
Observe the Solution info panel.
Observe grams column, approximately 2 grams of Potassium chloride remains undissolved.
Let us now check if increase in temperature increases or decreases the solubility.
Click on Select tool icon, choose Bunsen Burner.
Bring the Bunsen Burner close to flask 1.
Place flask 1 over Bunsen Burner.
The flask gets heated quickly and undissolved potassium chloride dissolves completely.
Observe the temperature, as temperature increases potassium chloride dissolves.
At approximately 40o C, potassium chloride dissolves completely. Note that grams column shows zero value.
We can turn off the flame of the Bunsen Burner when not required.
Click on the Burner. Two black arrows pointing up and down appear. Click on the down pointing arrow to turn off the Burner.
Now I will demonstrate the solubility of Cerium(III) Sulphate.
Note that solubility of Cerium(III) Sulphate is much lower than potassium chloride.
Transfer 50 mL of Distilled water to graduated cylinder using Precise transfer. Keep the Distilled water aside.
Now transfer 50 mL of Distilled water to flask 2 using Precise transfer. Keep the graduated cylinder aside.
Drag Weighing boat 2 and place it on the Scale. Click on TARE.
We will begin by dissolving just 1 gram of Cerium(III) Sulphate.
Transfer 1 gram of Cerium(III) Sulphate to Weighing boat 2.
Keep Cerium(III) Sulphate bottle aside.
Transfer 1 gram of Cerium(III) Sulphate from Weighing boat 2 to Flask 2. Keep the Weighing boat aside.
In the Solution Info panel, observe Species and grams columns.
Since all the Cerium(III) Sulphate is soluble in water, it indicates zero grams.
Let us add more Cerium(III) Sulphate to flask 2 to check the solubility.
Place the Weighing boat 2 back on the Scale. Press TARE. Weigh 5 grams of Cerium(III) Sulphate.
Change the transfer bar to Realistic Transfer.
Drag and place Weighing boat 2 over flask 2. Click on Pour button gradually.
Observe the Solution info panel.
Observe grams column, approximately 3 grams of Cerium(III) Sulphate remains undissolved.
Let us now check if increase in temperature increases or decreases the solubility.
Bring the Bunsen Burner close to flask 2. Place flask 2 over Bunsen Burner.
Click on the up pointing arrow to turn-on the burner.
Observe that grams column shows increase in value. As temperature increases, solubility of Cerium(III)Sulphate decreases.
Turn-off the Burner.
For potassium chloride, solubility increases with increase in temperature.
For Cerium(III)Sulphate, solubility decreases with increase in temperature.
Click on Problem description window. We need to check if dissolution of potassium chloride and Cerium (III) Sulphate is endothermic or exothermic.
Click on Workbench.
Let us delete Erlenmeyer Flasks from the workbench.
Click on the flask and press Delete on the keyboard.
Click on glassware icon. Select Foam Cup.
We need two copies of Foam Cups. Use Duplicate option from the Context menu.
Rename Foam Cups as 1 and 2.
Change the Transfer Bar to Precise Transfer.
Transfer 50 mL of Distilled water to graduated cylinder using Precise transfer. Keep the Distilled water aside.
Place Foam cups at a convenient location on the workbench.
Transfer 50 mL of Distilled water to Foam cup 1 using Precise transfer.
Click on Foam cup 1. In the Solution info panel, observe the temperature on the thermometer. It shows 25o C.
Foam cups act as Calorimeter for measurements made at constant pressure.
Heat exchange does not happen easily as it is a better insulator than glass.
Place the weighing boat 1 on the Scale. Press TARE.
Weigh 5 grams of potassium chloride.
Keep potassium chloride bottle aside.
Bring weighing boat 1 over to Foam cup 1. Type 5 in the transfer amount input bar. Click on pour.
Again click on Foam cup 1. Observe the temperature, it is now 21o Centigrade.
Dissolution of potassium chloride in water absorbs heat, hence temperature decreases.
It is an endothermic process.
Now let us repeat the same procedure for Cerium(III) Sulphate.
Fill the graduated cylinder with 50 mL Distilled water.
Transfer 50 mL of water from graduated cylinder to Foam cup 2.
Click on Foam cup 2. Note the temperature of water, it shows 25o Centigrade.
Place weighing boat 2 on the Scale. Press TARE.
Weigh 2 grams of Cerium(III) Sulphate. Keep Cerium(III) Sulphate bottle aside.
Drag Weighing boat 2 over to Foam cup 2.
Type 2 in the transfer amount input bar. Click on Pour.
Keep the Weighing boat aside.
Again Click on Foam cup 2. Observe the temperature, it is now 27.54o Centigrade.
Dissolution of Cerium(III) Sulphate in water releases heat, hence temperature increases. It is an exothermic process.
Let us now analyse the results. We observed that: For an endothermic process, solubility increases as temperature increases.
For an exothermic process, solubility decreases as temperature increases. These observations follow Le Chatelier's principle.
Let us summarize. In this tutorial we have Determined the solubilities of potassium Chloride and Cerium(III)sulphate with increase in temperature.
Observed that solubility of, potassium chloride is Endothermic and Solubility of Cerium(III)Sulphate is exothermic.
As an assignment, List some examples of exothermic and endothermic processes in your daily lives.
Explain why heat is absorbed or evolved during a reaction.
Determine whether dissolution of Sodium Chloride is exothermic or endothermic. (Hint: The problems are under Solubility topic in load homework window)
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This tutorial is contributed by Snehalatha kaliappan and Madhuri Ganapathi from IIT Bombay. Thank you for joining.