PhET-Simulations-for-Chemistry/C2/Concentration-and-Molarity/English

Title of script: Concentration and Molarity

Author: Radhika Yadav

Keywords: PhET simulation, concentration, molarity, solutions, moles, volume, solubility, saturation, spoken tutorial, video tutorial.

Visual Cue	Narration
Slide Number 1 Title Slide	Welcome to this Spoken Tutorial on Concentration and Molarity.
Slide Number 2 Learning Objectives	In this tutorial, we will learn: How change in concentration changes the color of the solution How change in volume changes the concentration of the solution To identify when the solution reaches the saturation point
Slide Number 3 System Requirements	This tutorial is recorded using, macOS Catalina version 10.15.7 Google Chrome version 101.0.49
Slide Number 4 Pre-requisites https://spoken-tutorial.org	To follow this tutorial, Learners should be familiar with topics in basic chemistry. Please use the link below to access the tutorials on PhET simulations.
Slide Number 5 Link for PhET simulation https://phet.colorado.edu/en/simulations/concentration https://phet.colorado.edu/en/simulations/molarity	Please use the given links to download the PhET simulations.
Slide Number 6 PhET simulations	In this tutorial, we will use, Concentration and Molarity PhET simulations.
Point to the simulation in the Downloads folder. Concentration and Molarity simulations.	I have already downloaded the simulations to my Downloads folder.
Point to the Concentration simulation.	We will begin with the Concentration simulation.
Double click on the concentration_en.html file.	To open the simulation, double click on the concentration_en.html file. The file opens in your default browser.
Point to the simulation interface.	This is the interface of the Concentration simulation.
Point to the beaker.	This is a graduated beaker that contains water.
Point to the faucet on the top left. Pull the lever to start adding water. Leave it to stop.	We can add water to the beaker using the top faucet. Pull the lever to start adding water. Leave it to stop.
Click the drop down arrow to show the list of solutes. Point to the Drink mix.	The Solute drop down list has nine different solutes. Drink mix is chosen by default.
Point to the radio buttons in Solute box on the top right Point to Solid radio button.	Below the list, we have Solid and Solution radio buttons. Solid is chosen by default.
Shake the dispenser containing the solute.	Let’s shake the Solid dispenser at the top to add solute in solid form.
Select Solution radio button.	We can use Solution dropper to add a concentrated solution.
Press the red button on tube containing solute	Press the red button on the dropper to add the solution.
Point to the Concentration tool.	The Concentration tool measures the concentration of a solution in moles per litre.
Drag the probe inside the beaker into the solution. Point to the concentration value. (number can vary)	Drag and place the probe inside the beaker into the solution. Our solution has 0.575 moles of drink mix in 1 litre of solution.
Point to the faucet on the bottom right. Pull the lever to drain the solution. Leave it to stop.	We can remove the solution from the beaker using the bottom right faucet. Pull the lever to drain the solution. Leave it to stop.
Point to the Evaporation box. Drag the slider of evaporation from none to lots . Point to the water level.	Drag the slider to select the level of evaporation from none to lots. Some amount of water will be removed from the solution. This will not affect the solution temperature.
Click the Remove Solute button to remove the solute. Point to the value in the tool.	The Remove Solute button removes all of the solute from the solution. Now the concentration tool reads 0.0 moles per litre.
Click the reset button.	Let us reset our screen.
Select cobalt chloride (CoCl2) from the drop down list in the Solute box.	Let us select cobalt chloride as solute from the drop down list.
Shake the dispenser containing the solute.	Shake the dispenser a few times to add solute to the water in the beaker.
Point to the beaker.	The solution turns a light red.
Drag the probe inside the beaker into the solution. Point to the value of concentration. (number can vary)	Drag the probe into the solution to check the concentration. It is 0.340 moles of cobalt chloride per litre of this solution.
Remove solution from the beaker using the bottom right faucet. Point to the volume of solution.	Remove half of the solution from the beaker using the bottom right faucet. Now the beaker has 0.25 litres of solution.
Point to the beaker.	The concentration and color remain the same.
Add water to the beaker using the top left faucet.	Let’s add 0.25 litres of water to the beaker to make it 0.5 litres of solution.
Point to the beaker. Point to the concentration value. (number can vary) Point to the beaker.	The concentration decreases to 0.176 moles per litre. This is because the solute amount is same but solution volume has increased. The solution turns a lighter red.
Select Solution radio button.	Select the Solution radio button in the Solute box.
Press the red button on tube containing solute. Point to the volume in the beaker.	Press the red button on the dropper to add solute. Add 0.3 litres to the solution. There is 0.8 litres of solution in the beaker after this.
Point to the beaker. Point to the concentration value. (number can vary). Point to the beaker.	The concentration increases to 1.634 moles per litre. This is because the solute amount has increased. The solution turns a darker red.
Point to the Evaporation box. Drag the slider from none to lots.	Now remove water from the solution using the slider in the Evaporation box. Bring the solution back to the half litre mark.
Point to the beaker. Point to the concentration value. (number can vary)	The concentration increases to 2.661 moles per litre. The solution further becomes a darker red.
Select Solid radio button.	Select the Solid radio button again.
Shake the dispenser containing the solute. Point to the solute particles at the bottom.	Keep adding the solute till no more of it dissolves. The solute particles settle at the bottom of the beaker.
Point to the beaker. Point to the banner.	A banner indicating that the solution has saturated appears. A saturated solution means the solution cannot dissolve any more of the solute. This value is noted at a fixed temperature and pressure. The saturation point for cobalt chloride is at 4.330 moles per litre.
Shake the dispenser containing the solute.	On adding more solute, there will be no change in the concentration. Even the color remains the same.
Click the reset button.	Let us reset our screen.
Select copper (II) sulfate (CuSO4) from the drop down list in the Solute box.	Select copper sulfate from the drop down list.
Drag the probe inside the beaker into the solution.	Drag the probe inside the beaker into the solution.
Shake the dispenser containing the solute. Point to the solution in the beaker.	Once again, add solute to the solution till it saturates. Note that the solution becomes increasingly blue. The saturation point for copper sulfate is at 1.380 moles per litre.
Slide Number 7 Assignment	Pause the tutorial and do the following assignment. Find the molarity at the saturation point for all the remaining solutes and fill this table.
Cursor in the Downloads folder.	Now let us explore the Molarity simulation.
Double click on the molarity_en.html file.	To open the simulation, double click on the molarity_en.html file. The file will open in your default browser.
Point to the simulation interface. Point to the mic button.	This is the interface of the Molarity simulation. You can adjust the simulation volume at the bottom right of the screen.
Point to the beaker.	This beaker contains our solution.
Point to the Solute Amount slider on the left.	Using the Solute Amount slider, we can select the amount of solute in moles. It ranges from none to lots.
Point to the Solution Volume slider.	Using the Solution Volume slider, we can select the solution volume in litres. It ranges from low to full.
Check the Solution Values checkbox at the bottom left.	Select the Solution Values checkbox. It displays the numerical values for moles, Litres and the Molarity.
Point to the Solute drop down list in the bottom centre. Point to Drink mix.	At the bottom, is the Solute drop down list. Drink mix is selected by default.
Point to the Solution Concentration bar on the right.	The solution concentration bar on the right displays the molarity. It ranges from zero to high. Numerically, it ranges from 0 to 5. It is at 1 M by default. We have already seen how solution color changes with concentration. The bar also reflects the same.
Click the to the reset button.	Let us reset our screen.
Select potassium chromate (K2CrO4) from the Solute drop down list.	Let us select potassium chromate as solute from the drop down list.
Check the Solution Values checkbox.	Check the Solution Values checkbox.
Drag the Solute Amount slider upwards to increase solute amount.	Drag the Solute Amount slider upwards to add more solute. Increase it to 1 mol.
Point to the Solution Concentration bar on the right.	The concentration also increases and is now 2 M as 1/0.5 is equal to 2.
Point to the beaker.	The color of the solution darkens.
Drag the Solution Volume slider upwards to increase solution volume.	Increase the solution volume by dragging the Solution Volume slider upwards. Increase it to 0.75 litres.
Point to the Solution Concentration bar on the right.	Observe that the concentration decreases to 1.33 M as 1/0.75 is 1.33. This is because the amount of solute is same but solution volume has increased. Hence, the number of moles per litre of the solution have decreased.
Point to the beaker.	The color of the solution lightens.
Drag the Solution Volume slider downwards to decrease solution volume.	Let us now decrease the solution volume to saturate the solution. Drag the Solution Volume slider downwards. At 0.298 litres, molecules of potassium chromate will stop dissolving.
Point to the beaker.	Just like before, a banner indicating that the solution has saturated appears.
Point to the Solution Concentration bar on the right.	The concentration increased to 3.350 M as 1/0.298 is equal to 3.35. The number of moles have remained the same but solution volume has decreased. Hence, the number of moles per litre of the solution have increased.
Point to the beaker.	The solution color has become darker again.
Drag the Solution Volume slider downwards to decrease solution volume.	On decreasing the volume further crystals of potassium chromate are seen. Here the concentration and colour of the solution remain the same.
Slide Number 8 Assignment	See the following table. It contains all the solutes given in the simulation. As an assignment, Use the given values to calculate concentration. Then verify the result using the Molarity simulation.
Only Narration.	With this, we have come to the end of this tutorial. Let us summarise.
Slide Number 9 Summary	In this tutorial, we have learnt, How change in concentration changes the color of the solution How change in volume changes the concentration of the solution To identify when the solution reaches the saturation point
Slide Number 10 About the Spoken Tutorial project	The video at the following link summarises the Spoken Tutorial project. Please download and watch it.
Slide Number 11 Spoken Tutorial workshops	The Spoken Tutorial Project team: conducts workshops using spoken tutorials and gives certificates on passing online tests. For more details, please write to us.
Slide Number 12 Forum for specific questions Do you have questions in THIS Spoken Tutorial? Please visit this site. Choose the minute and second where you have the question. Explain your question briefly. The Spoken tutorial project will ensure an answer. You will have to register to ask questions.	Please post your timed queries in this forum.
Slide Number 13 Acknowledgement	The Spoken Tutorial project is funded by the Ministry of Education, Government of India.
Slide Number 14 Thank you	This is Radhika Yadav, a FOSSEE summer fellow 2022, IIT Bombay signing off. Thanks for joining.

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