PhET/C2/pH-Scale/English-timed

Time	Narration
00:01	Welcome to this Spoken tutorial on pH scale using interactive PhET simulation.
00:08	In this tutorial, we will learn how to use interactive PhET simulation, pH scale.
00:15	To follow this tutorial,learners should be familiar with topics in high school science.
00:22	Here I am using- Ubuntu Linux OS version 14.04 Java version 1.7.0 Firefox Web Browser version 53.02.2.
00:38	Using this simulation, we will learn to- 1. Determine whether a given solution is an acid or a base.
00:49	2. Arrange acids and bases according to their strength 3. Determine the concentration of hydroxide ion, hydronium ion and water at a given pH.
01:01	Using this simulation, we will learn about: 4. pH of a solution 5. Effect of dilution on pH of a solution 6.Logarithmic and Linear scale.
01:16	pH scale is a numeric scale used to specify the acidity or basicity of an aqueous solution.
01:25	pH is a measure of hydrogen ion concentration in mol/L.
01:30	pH is negative logarithm to base 10 of hydrogen ion concentration. pH = - log[H]
01:37	For acidic solutions, pH is less than 7(< 7).
01:42	For basic solutions, pH is greater than 7 (> 7).
01:47	For neutral solutions, pH is equal to 7 (= 7).
01:52	Use the given link to download the simulation. http://phet.colorado.edu
01:57	I have already downloaded the pH Scale PhET, to my Downloads folder.
02:02	To open the simulation, right-click on ph-scale html file.
02:08	Choose the option Open With Firefox Web Browser. The file opens in the browser.
02:16	This is the interface of pH scale simulation.
02:20	The interface has three screens- Macro Micro My solution
02:27	Let us begin our simulation with Macro screen. Click on Macro screen to open it.
02:36	This screen has- A pH scale on the left, to display pH range from 0 to 14.
02:44	A green probe attached to pH scale, to measure pH and A pH meter to show pH of the liquids.
02:54	A water pump on the right side of screen to add water.
02:59	A graduated water container filled by default, with Chicken Soup.
03:05	A pump to remove solution is attached at the bottom left of the container.
03:11	A dropper to add liquid.
03:14	A drop down box to choose one of the liquids. By default, Chicken Soup is selected.
03:22	A Reset button is provided at the right hand side bottom corner.
03:28	Click on the drop-down arrow.
03:31	Scroll to Battery Acid and click on it. Notice that the container is filled with Battery Acid up to 0.50 L (0.5 litres).
03:42	Drag the green probe into the container and observe the pH.
03:48	Meter shows the pH value as 1.0. As pH is less than 7(<7), Battery Acid is an acidic solution.
03:58	Now click on the water pump to add more water.
04:03	Increase the water level up to 1 Litre. Observe the change in pH on addition of water. Now pH meter shows pH value as 1.30.
04:16	Notice that pH of Battery Acid increases on addition of water. This is because hydrogen [H] ion concentration decreases with dilution.
04:28	Now we will select another solution.
04:32	Click on drop down arrow.
04:34	Scroll to Hand Soap and click on it. Container is filled with Hand Soap solution.
04:42	Here, pH meter shows the value of pH as 10.00. This indicates that Hand Soap is basic in nature.
04:54	Click on water pump to add water to Hand Soap solution.
04:59	For 1 L, Hand Soap solution shows a pH value of 9.70.
05:06	We can see that pH of Hand Soap solution decreases on dilution.
05:12	This is because hydroxide ion (OH) concentration decreases with dilution.
05:18	Click on the bottom pump to remove half litre of Hand Soap solution.
05:24	Click on the dropper and increase the level of Hand Soap solution to 0.6 L. Notice the change in pH.
05:34	It increases as concentration of hydroxide ion (OH) increases.
05:39	Now we will arrange the acids and bases according to their strengths.
05:45	For that, we will check the pH of different liquids.
05:50	Click on drop down arrow and select Blood. Container is filled with Blood up to 0.50 L.
05:59	Meter shows the pH value as 7.40. As pH is greater than 7( >7), Blood is a basic solution.
06:09	Again click on drop down arrow and select Orange Juice.
06:14	Meter shows pH value as 3.50 for 0.50 L. It is clear that Orange Juice is an acidic solution.
06:26	According to the above pH values the order is as follows. Hand soap > Blood > Orange Juice > Battery Acid.
06:38	As an assignment, Check the pH of each liquid. And, arrange the liquids according to the pH range.
06:48	Now, we will move on to Micro screen. Click on Micro screen at the bottom of the interface.
06:57	This screen has the following tools- A pH scale on the left hand side of screen,
07:04	A switch on the top of pH scale to select between Concentration and Quantity, A red button with a minus(-) to hide pH scale,
07:16	A switch at the bottom to select between Logarithmic and Linear scale.
07:22	Check boxes to select- Hydronium ion to hydroxide ion ratio (H30+/OH- ) and Molecule count,
07:30	In the pH meter, a red button with a minus(-) to hide pH reader and value.
07:38	Click on the drop down arrow and select Soda Pop. Container is filled with Soda Pop.
07:46	pH meter shows pH value as 2.50. It means, Soda Pop is an acidic solution.
07:54	As Soda Pop is acidic, concentration of hydronium ion is high and hydroxide ion is low.
08:02	Then click on Quantity(mol).
08:05	We will see the number of moles of hydronium ion, hydroxide ion and water.
08:12	Let us change Logarithmic scale to Linear. To do so, click on Linear .
08:20	The pH scale changes to Linear mode. We also see that pH values become Linear.
08:28	But we will not use Linear scale as pH is in Logarithmic scale.
08:34	Click on Hydronium ion to hydroxide ion ratio (H30+/OH-) check box.
08:39	A large number of red dots are seen in the container. These are hydronium ions.
08:46	A few blue dots that are seen are hydroxide ions(</sup>/OH-).
08:51	To see count of molecules in Soda Pop, click on Molecule count check box.
08:57	Count of hydronium ions, hydroxide ions and water molecules in Soda Pop is seen.
09:05	Let us see how dilution affects the number of molecules.
09:10	Click on water pump, fill the container up to 1 L. Observe the change in Molecule Count. Note the increase in pH value. pH becomes 2.80.
09:25	As an assignment, measure the pH of Blood sample.
09:30	Observe the change in Molecule Count and H30+/OH- ratio after dilution.
09:37	Now, we will move on to My Solution screen. Click on My Solution screen at the bottom of the interface.
09:46	My Solution screen has the same tools as that of Macro and Micro screens.
09:53	This screen also has some additional tools:
09:57	a graduated container on the right hand side of screen, a pH meter to adjust pH directly.
10:05	This screen allows direct manipulation of pH or ion concentration.
10:11	In this screen, we can make a solution of our choice in two ways- 1. By moving the H30+or OH- slider on pH scale, 2. By clicking black arrow upwards or downwards.
10:28	Let us move the hydronium ion (H30+) slider upwards.
10:32	Notice that, simultaneously Hydroxide ion (OH-) slider also moves downwards.
10:38	Let's make a solution of pH 4.0 by clicking the black arrow downwards. This is an acidic solution.
10:48	Now, click on Hydronium ion to hydroxide ion (H30+/OH-) ratio and Molecule count check boxes.
10:55	Notice that Molecule count for hydronium ion (H30+) is 3.01 x 1019.
11:01	As an assignment, make solutions of pH 7.0 and 9.0. Observe and compare the change in molecules.
11:13	Let us summarize. In this tutorial, we have learnt about interactive PhET simulation, pH scale.
11:22	Using this simulation, we have learnt to- 1.Determine whether a given solution is an acid or a base.
11:31	2. Arrange acids and bases according to their strength.
11:36	3. Determine the concentration of hydronium ion, hydroxide ion and water at a given pH
11:43	4. pH of a solution 5. Effect of dilution on pH of solution 6. Logarithmic and Linear scale.
11:53	The video at the following link summarizes the Spoken Tutorial project. Please download and watch it.
12:02	The Spoken Tutorial Project team: Conducts workshops using spoken tutorials and gives certificates on passing online tests. For more details, please write to us.
12:15	Please post your timed queries in this forum.
12:21	This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching.
12:29	Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India. More information on this mission is available at this link.
12:41	This is Meenal Ghoderao from IIT Bombay. Thank you for joining.

Contributors and Content Editors

Madhurig, PoojaMoolya, Sandhya.np14