Difference between revisions of "PhET/C2/pH-Scale/English-timed"

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|-  
 
|-  
 
|00:01
 
|00:01
−
| Welcome to this Spoken tutorial on '''pH scale''' using '''interactive PhET simulation'''.
+
| Welcome to this '''Spoken tutorial''' on '''pH scale''' using interactive '''PhET simulation'''.
  
 
|-
 
|-
 
|00:08
 
|00:08
−
| In this tutorial we will learn-
+
| In this tutorial, we will learn how to use interactive '''PhET simulation''', '''pH scale'''.
−
 
+
−
How to use '''interactive PhET simulation''', '''pH scale'''.
+
  
 
|-
 
|-
 
|00:15
 
|00:15
−
| To follow this tutorial,  
+
| To follow this tutorial,learners should be familiar with topics in high school science.
−
 
+
−
Learners should be familiar with topics in high school science.
+
  
 
|-
 
|-
Line 23: Line 19:
 
| Here I am using-
 
| Here I am using-
  
−
Ubuntu Linux OS version 14.04
+
'''Ubuntu Linux OS''' version 14.04
  
−
Java version 1.7.0
+
'''Java''' version 1.7.0
  
−
Firefox Web Browser version 53.02.2.
+
'''Firefox Web Browser''' version 53.02.2.
  
 
|-
 
|-
 
|00:38
 
|00:38
−
| Using this '''simulation''' we will learn to-
+
| Using this '''simulation''', we will learn to-
−
Determine whether a given solution is an '''acid''' or a '''base'''.
+
1. Determine whether a given solution is an acid or a base.
  
 
|-
 
|-
 
|00:49
 
|00:49
−
|Arrange '''acids''' and '''bases''' according to their strength,
+
|2. Arrange acids and bases according to their strength
−
Determine the '''concentration''' of '''hydroxide ion''',
+
3. Determine the concentration of hydroxide ion, hydronium ion and water at a given '''pH'''.
−
'''hydronium ion''' and '''water''' at a given '''pH'''.
+
  
 
|-
 
|-
 
|01:01
 
|01:01
−
| Using this '''simulation''' we will learn about,
+
| Using this '''simulation''', we will learn about:
 +
4. '''pH''' of a solution
  
−
'''pH''' of a solution.
+
5. Effect of dilution on '''pH''' of a solution
  
−
Effect of dilution on '''pH''' of a solution.
+
6.'''Logarithmic''' and '''Linear''' scale.
−
 
+
−
'''Logarithmic''' and '''Linear''' scale.
+
  
 
|-
 
|-
 
|01:16
 
|01:16
−
| '''pH scale''' is a, numeric scale used to specify the '''acidity''' or '''basicity''' of an aqueous solution.
+
| '''pH scale''' is a numeric scale used to specify the acidity or basicity of an aqueous solution.
  
 
|-
 
|-
 
|01:25
 
|01:25
−
| '''pH''' is a measure of '''hydrogen ion concentration''' in mol/L.
+
| '''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''' is negative logarithm to base 10 of hydrogen ion concentration.
 +
 
 
'''pH = - log[H]'''
 
'''pH = - log[H]'''
  
 
|-
 
|-
 
|01:37
 
|01:37
−
| For '''Acidic''' solutions, '''pH''' is less than 7(< 7).
+
| For acidic solutions, '''pH''' is less than 7(< 7).
  
 
|-
 
|-
 
|01:42
 
|01:42
−
|For '''Basic''' solutions, '''pH''' is greater than 7 (> 7).
+
|For basic solutions, '''pH''' is greater than 7 (> 7).
  
 
|-
 
|-
 
|01:47
 
|01:47
−
|For '''Neutral''' solutions, '''pH''' is equal to 7 (= 7).
+
|For neutral solutions, '''pH''' is equal to 7 (= 7).
  
 
|-
 
|-
 
|01:52
 
|01:52
 
| Use the given link to download the '''simulation'''.
 
| Use the given link to download the '''simulation'''.
−
 
 
[http://phet.colorado.edu/ http://phet.colorado.edu]
 
[http://phet.colorado.edu/ http://phet.colorado.edu]
  
Line 87: Line 81:
 
|-
 
|-
 
|02:02
 
|02:02
−
| To open the '''simulation''', right click on '''ph-scale html file'''.
+
| To open the '''simulation''', right-click on '''ph-scale html file'''.
  
 
|-
 
|-
 
|02:08
 
|02:08
−
|Choose the option '''Open With Firefox Web Browser'''. The file opens in the '''Browser'''.
+
|Choose the option '''Open With Firefox Web Browser'''. The file opens in the browser.
  
 
|-
 
|-
 
|02:16
 
|02:16
−
| This is the ''' interface'''of '''pH scale simulation'''.
+
| This is the '''interface''' of '''pH scale simulation'''.
  
 
|-
 
|-
 
|02:20
 
|02:20
−
| The '''interface''' has three screens-
+
| The interface has three screens-
  
 
'''Macro'''  
 
'''Macro'''  
Line 119: Line 113:
 
|-
 
|-
 
|02:44
 
|02:44
−
|A green '''probe''' attached to '''pH scale''' to measure '''pH''' and  A '''pH meter''' to show '''pH''' of the liquids.
+
|A green '''probe''' attached to '''pH scale''', to measure '''pH''' and  A '''pH meter''' to show '''pH''' of the liquids.
  
 
|-
 
|-
 
|02:54
 
|02:54
−
| A '''Water pump''' on the right side of screen to add '''water'''.
+
| A water pump on the right side of '''screen''' to add water.
  
 
|-
 
|-
 
|02:59
 
|02:59
−
|A Graduated '''water container''' filled by default with '''Chicken Soup'''.
+
|A graduated water container filled by default, with '''Chicken Soup'''.
  
 
|-
 
|-
 
|03:05
 
|03:05
−
|A '''pump''' to remove solution is attached at the bottom left of the '''container'''.
+
|A pump to remove solution is attached at the bottom left of the container.
  
 
|-
 
|-
 
|03:11
 
|03:11
−
| A '''Dropper''' to add liquid.
+
| A '''dropper''' to add liquid.
  
 
|-
 
|-
 
|03:14
 
|03:14
−
|A '''Drop down box''' to choose one of the liquids.By default '''Chicken Soup''' is selected.
+
|A drop down box to choose one of the liquids. By default, '''Chicken Soup''' is selected.
  
 
|-
 
|-
 
|03:22
 
|03:22
−
| A '''Reset Button''' is provided at the right hand side bottom corner.
+
| A '''Reset''' button is provided at the right hand side bottom corner.
  
 
|-
 
|-
 
|03:28
 
|03:28
−
| Click on the '''drop down arrow'''.
+
| Click on the drop-down arrow.
  
 
|-
 
|-
 
|03:31
 
|03:31
−
|Scroll to '''Battery Acid ''' and click on it. Notice that, the '''container''' is filled with '''Battery Acid''' up to 0.50 L (0.5litres).
+
|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
 
|03:42
−
| Drag the green '''probe''' into the '''container''' and Observe the '''pH'''.  
+
| Drag the green '''probe''' into the container and observe the '''pH'''.  
  
 
|-
 
|-
 
|03:48
 
|03:48
−
|'''Meter''' shows the '''pH''' value as 1.0. As '''pH''' is less than 7(<7), '''Battery Acid''' is an '''acidic''' solution.
+
|'''Meter''' shows the '''pH''' value as 1.0. As '''pH''' is less than 7(<7), '''Battery Acid''' is an acidic solution.
  
 
|-
 
|-
 
|03:58
 
|03:58
−
| Now click on the '''water pump''' to add more '''water'''.
+
| Now click on the water pump to add more water.
  
 
|-
 
|-
 
|04:03
 
|04:03
−
|Increase the '''water''' level up to 1Litre. Observe the change in '''pH''' on addition of '''water'''.
+
|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.
 
Now '''pH meter''' shows '''pH''' value as 1.30.
  
 
|-
 
|-
 
|04:16
 
|04:16
−
| Notice that '''pH''' of '''Battery Acid''' increases on addition of '''water'''. This is because '''hydrogen [H] ion concentration''' decreases with dilution.
+
| Notice that '''pH''' of '''Battery Acid''' increases on addition of water.  
 +
This is because hydrogen [H] ion concentration decreases with dilution.
  
 
|-
 
|-
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|-
 
|-
 
|04:32
 
|04:32
−
| Click on '''drop down arrow'''.
+
| Click on drop down arrow.
  
 
|-
 
|-
 
|04:34
 
|04:34
−
|Scroll to '''Hand Soap''' and click on it. '''Container''' is filled with '''Hand Soap''' solution.
+
|Scroll to '''Hand Soap''' and click on it. Container is filled with '''Hand Soap''' solution.
  
 
|-
 
|-
 
|04:42
 
|04:42
−
| Here, '''pH meter''' shows the value of '''pH''' as 10.00. This indicates that '''Hand Soap''' is '''basic''' in nature.
+
| Here, '''pH meter''' shows the value of '''pH''' as 10.00. This indicates that '''Hand Soap''' is basic in nature.
  
 
|-
 
|-
 
|04:54
 
|04:54
−
| Click on '''water pump''' to add '''water''' to ''' Hand Soap''' solution.
+
| Click on water pump to add water to '''Hand Soap''' solution.
  
 
|-
 
|-
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|-
 
|-
 
|05:12
 
|05:12
−
|This is because '''hydroxide ion (OH) concentration''' decreases with dilution.
+
|This is because hydroxide ion (OH) concentration decreases with dilution.
  
 
|-
 
|-
 
|05:18
 
|05:18
−
| Click on the bottom '''pump''' to remove half litre of '''Hand Soap''' solution.
+
| Click on the bottom pump to remove half litre of '''Hand Soap''' solution.
  
 
|-
 
|-
 
|05:24
 
|05:24
−
|Click on the '''dropper''' and increase the level of '''Hand Soap''' solution to 0.6 L. Notice the change in '''pH'''.
+
|Click on the dropper and increase the level of '''Hand Soap''' solution to 0.6 L. Notice the change in '''pH'''.
  
 
|-
 
|-
 
|05:34
 
|05:34
−
|It increases as '''concentration''' of '''hydroxide ion (OH)''' increases.  
+
|It increases as concentration of hydroxide ion (OH) increases.  
  
 
|-
 
|-
 
|05:39
 
|05:39
−
| Now we will arrange the '''acids''' and '''bases''' according to their strengths.
+
| Now we will arrange the acids and bases according to their strengths.
  
 
|-
 
|-
 
|05:45
 
|05:45
−
|For that we will check the '''pH''' of different liquids.
+
|For that, we will check the '''pH''' of different liquids.
  
 
|-
 
|-
 
|05:50
 
|05:50
−
| Click on '''drop down arrow''' and select '''Blood'''. '''Container''' is filled with '''Blood''' up to 0.50 L.
+
| Click on drop down arrow and select '''Blood'''. Container is filled with '''Blood''' up to 0.50 L.
  
 
|-
 
|-
 
|05:59
 
|05:59
−
| '''Meter''' shows the '''pH''' value as 7.40. As '''pH''' is greater than 7( >7), '''Blood''' is a '''basic''' solution.
+
| '''Meter''' shows the '''pH''' value as 7.40. As '''pH''' is greater than 7( >7), '''Blood''' is a basic solution.
  
 
|-
 
|-
 
|06:09
 
|06:09
−
|Again click on '''drop down arrow''' and select '''Orange Juice'''.
+
|Again click on drop down arrow and select '''Orange Juice'''.
  
 
|-
 
|-
 
|06:14
 
|06:14
−
|'''Meter''' shows '''pH''' value as 3.50 for 0.50 L. It is clear that '''Orange Juice''' is an '''acidic''' solution.
+
|'''Meter''' shows '''pH''' value as 3.50 for 0.50 L. It is clear that '''Orange Juice''' is an acidic solution.
  
 
|-
 
|-
 
|06:26
 
|06:26
 
| According to the above '''pH''' values the order is as follows.  
 
| According to the above '''pH''' values the order is as follows.  
−
 
+
'''Hand soap''' > '''Blood''' > '''Orange Juice''' > '''Battery Acid'''.
−
'''Hand soap > Blood > Orange Juice> Battery Acid'''.
+
  
 
|-
 
|-
 
|06:38
 
|06:38
 
| As an assignment,
 
| As an assignment,
−
 
 
Check the '''pH''' of each liquid.
 
Check the '''pH''' of each liquid.
−
 
+
And, arrange the liquids according to the '''pH''' range.
−
And arrange the liquids according to the '''pH''' range.
+
  
 
|-
 
|-
 
|06:48
 
|06:48
−
|Now, we will move on to Micro screen. Click on Micro screen at the bottom of the interface.  
+
|Now, we will move on to '''Micro''' screen. Click on '''Micro''' screen at the bottom of the interface.  
  
 
|-
 
|-
 
|06:57
 
|06:57
 
|This screen has the following tools-
 
|This screen has the following tools-
−
 
+
A '''pH scale''' on the left hand side of screen,
−
A '''pH scale''' on the left hand side of screen.
+
  
 
|-
 
|-
 
|07:04
 
|07:04
−
|A switch on the top of '''pH scale''' to select between '''Concentration''' and '''Quantity'''.
+
|A switch on the top of '''pH scale''' to select between '''Concentration''' and '''Quantity''',
−
 
+
A red button with a minus(-) to hide '''pH scale''',
−
A red button with a minus(-) to hide '''pH scale'''.
+
  
 
|-
 
|-
Line 279: Line 269:
 
|07:22
 
|07:22
 
| Check boxes to select-
 
| Check boxes to select-
−
 
+
'''Hydronium ion''' to '''hydroxide ion ratio''' '''(H<sub>3</sub>0<sup>+</sup>/OH<sup>-</sup> )''' and  '''Molecule count''',
−
'''Hydronium ion''' to '''hydroxide ion ratio''' '''(H<sub>3</sub>0<sup>+</sup>/OH<sup>-</sup> )''' and  '''Molecule count'''.
+
  
 
|-
 
|-
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|-
 
|-
 
|07:38
 
|07:38
−
| Click on the '''drop down arrow''' and select '''Soda Pop'''.'''Container''' is filled with '''Soda Pop'''.
+
| Click on the drop down arrow and select '''Soda Pop'''.
 +
Container is filled with '''Soda Pop'''.
  
 
|-
 
|-
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|-
 
|-
 
|07:54
 
|07:54
−
| As '''Soda Pop''' is '''acidic''', '''Concentration''' of '''hydronium ion''' is high and '''hydroxide ion''' is low.
+
| As '''Soda Pop''' is acidic, concentration of hydronium ion is high and hydroxide ion is low.
  
 
|-
 
|-
 
|08:02
 
|08:02
−
| Then click on '''Quantity(mol)''',
+
| Then click on '''Quantity(mol)'''.
  
 
|-
 
|-
 
|08:05
 
|08:05
−
|We will see the number of moles of '''hydronium ion''', '''hydroxide ion''' and '''water'''.
+
|We will see the number of '''moles''' of hydronium ion, hydroxide ion and water.
  
 
|-
 
|-
 
|08:12
 
|08:12
−
| Let us change '''Logarithmic scale''' to '''Linear'''. To do so click on '''Linear''' .
+
| Let us change '''Logarithmic scale''' to '''Linear'''. To do so, click on '''Linear''' .
  
 
|-
 
|-
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|-
 
|-
 
|08:34
 
|08:34
−
| Click on''' Hydronium ion '''to''' hydroxide ion ratio (H<sub>3</sub>0<sup>+</sup>/OH<sup>-</sup>) ''' check box.
+
| Click on Hydronium ion to hydroxide ion ratio '''(H<sub>3</sub>0<sup>+</sup>/OH<sup>-</sup>)''' check box.
  
 
|-
 
|-
 
|08:39
 
|08:39
−
|A large number of red dots are seen in the '''container'''. These are '''hydronium ions'''.
+
|A large number of red dots are seen in the container. These are hydronium ions.
  
 
|-
 
|-
 
|08:46
 
|08:46
−
|A few blue dots that are seen are '''hydroxide ions''' (OH).  
+
|A few blue dots that are seen are hydroxide ions'''(</sup>/OH<sup>-</sup>)'''.  
  
 
|-
 
|-
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|-
 
|-
 
|08:57
 
|08:57
−
|Count of '''hydronium ions''', '''hydroxide ions''' and '''water''' molecules in '''Soda Pop''' is seen.
+
|Count of hydronium ions, hydroxide ions and water molecules in '''Soda Pop''' is seen.
  
 
|-
 
|-
Line 344: Line 334:
 
|-
 
|-
 
|09:10
 
|09:10
−
|Click on '''water pump''', fill the '''container''' up to 1 L. Observe the change in '''Molecule Count'''.
+
|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.
 
Note the increase in '''pH''' value. '''pH''' becomes 2.80.
  
 
|-
 
|-
 
|09:25
 
|09:25
−
| As an '''assignment''', Measure the '''pH''' of '''Blood''' sample.
+
| As an assignment, measure the '''pH''' of '''Blood''' sample.
  
 
|-
 
|-
Line 357: Line 347:
 
|-
 
|-
 
|09:37
 
|09:37
−
| Now, we will move on to '''My Solution''' screen. Click on '''My Solution''' screen at the bottom of the '''interface'''.
+
| Now, we will move on to '''My Solution''' screen. Click on '''My Solution''' screen at the bottom of the interface.
  
 
|-
 
|-
Line 365: Line 355:
 
|-
 
|-
 
|09:53
 
|09:53
−
| This screen also has some additional tools.
+
| This screen also has some additional tools:
  
 
|-
 
|-
 
|09:57
 
|09:57
−
|A Graduated '''container''' on the right hand side of screen. A '''pH meter''' to adjust '''pH''' directly.
+
|a graduated container on the right hand side of screen, a '''pH meter''' to adjust '''pH''' directly.
  
 
|-
 
|-
 
|10:05
 
|10:05
−
| This screen allows direct manipulation of '''pH''' or ion '''concentration'''.
+
| This screen allows direct manipulation of '''pH''' or ion concentration.
  
 
|-
 
|-
Line 379: Line 369:
 
| In this screen, we can make a solution of our choice in two ways-
 
| In this screen, we can make a solution of our choice in two ways-
  
−
By moving the '''H<sub>3</sub>0<sup>+'''</sup>or '''OH<sup>-'''</sup> slider on '''pH scale'''.
+
1. By moving the '''H<sub>3</sub>0<sup>+'''</sup>or '''OH<sup>-'''</sup> slider on '''pH scale''',
  
−
By clicking black arrow upwards or downwards.
+
2. By clicking black arrow upwards or downwards.
  
 
|-
 
|-
 
|10:28
 
|10:28
−
| Let us move the '''hydronium ion (H<sub>3</sub>0<sup>+</sup>)''' slider upwards.
+
| Let us move the hydronium ion '''(H<sub>3</sub>0<sup>+</sup>)''' slider upwards.
  
 
|-
 
|-
 
|10:32
 
|10:32
−
|Notice that, simultaneously '''Hydroxide ion(OH<sup>-</sup>)''' slider also moves downwards.
+
|Notice that, simultaneously Hydroxide ion '''(OH<sup>-</sup>)''' slider also moves downwards.
  
 
|-
 
|-
 
|10:38
 
|10:38
−
| Let's make a solution of '''pH''' 4.0 by clicking the black arrow downwards. This is an '''acidic''' solution.
+
| Let's make a solution of '''pH''' 4.0 by clicking the black arrow downwards. This is an acidic solution.
  
 
|-
 
|-
 
|10:48
 
|10:48
−
| Now, Click on '''Hydronium ion''' to '''hydroxide ion (H<sub>3</sub>0<sup>+</sup>/OH<sup>-</sup> )ratio''' and '''Molecule count''' check boxes.
+
| Now, click on Hydronium ion to hydroxide ion '''(H<sub>3</sub>0<sup>+</sup>/OH<sup>-</sup>)''' ratio and '''Molecule count''' check boxes.
  
 
|-
 
|-
 
|10:55
 
|10:55
−
|Notice that '''Molecule count''' for '''hydronium ion''' (H<sub>3</sub>0<sup>+</sup>)<sup> </sup>is 3.01 x 10<sup>19</sup>.
+
|Notice that '''Molecule count''' for hydronium ion '''(H<sub>3</sub>0<sup>+</sup>)<sup> </sup>is 3.01 x 10<sup>19</sup>'''.
  
 
|-
 
|-
 
|11:01
 
|11:01
−
| As an '''assignment''',
+
| As an assignment,
−
 
+
make solutions of '''pH''' 7.0 and 9.0.
−
Make solutions of '''pH''' 7.0 and 9.0.
+
−
 
+
 
Observe and compare the change in molecules.
 
Observe and compare the change in molecules.
  
Line 414: Line 402:
 
|11:13
 
|11:13
 
| Let us summarize.
 
| Let us summarize.
−
 
+
In this tutorial, we have learnt about interactive '''PhET simulation, pH scale'''.
−
In this tutorial we have learnt about, '''interactive PhET simulation, pH scale'''.
+
  
 
|-
 
|-
 
|11:22
 
|11:22
−
| Using this simulation we have learnt to-
+
| Using this simulation, we have learnt to-
  
−
Determine whether a given solution is an '''acid''' or a '''base'''.
+
1.Determine whether a given solution is an acid or a base.
  
 
|-
 
|-
 
|11:31
 
|11:31
−
|Arrange '''acids''' and '''bases''' according to their strength.  
+
|2. Arrange acids and bases according to their strength.  
−
 
+
 
|-
 
|-
 
|11:36
 
|11:36
−
|Determine the concentration of '''hydronium ion''', '''hydroxide ion''' and '''water''' at a given '''pH'''.
+
|3. Determine the concentration of hydronium ion, hydroxide ion and water at a given '''pH'''
  
 
|-
 
|-
 
|11:43
 
|11:43
−
| '''pH''' of a solution.
+
|4. '''pH''' of a solution
−
 
+
5. Effect of dilution on '''pH''' of solution
−
Effect of dilution on '''pH''' of solution.
+
6. '''Logarithmic''' and '''Linear scale'''.
−
 
+
−
'''Logarithmic''' and '''Linear scale'''.
+
  
 
|-
 
|-
 
|11:53
 
|11:53
−
| The '''video''' at the following link summarizes the Spoken Tutorial project. Please download and watch it.
+
| The video at the following link summarizes the Spoken Tutorial project. Please download and watch it.
  
 
|-
 
|-
 
|12:02
 
|12:02
−
| The '''Spoken Tutorial Project''' team:
+
| The '''Spoken Tutorial''' Project team:
−
 
+
 
Conducts workshops using spoken tutorials and gives certificates on passing online tests.
 
Conducts workshops using spoken tutorials and gives certificates on passing online tests.
 
For more details, please write to us.
 
For more details, please write to us.
Line 460: Line 443:
 
|-
 
|-
 
|12:29
 
|12:29
−
| Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India. More information on this mission is available at this link.
+
| Spoken Tutorial Project is funded by '''NMEICT, MHRD,''' Government of India. More information on this mission is available at this link.
  
 
|-
 
|-
 
|12:41
 
|12:41
 
| This is '''Meenal Ghoderao''' from '''IIT Bombay'''. Thank you for joining.
 
| This is '''Meenal Ghoderao''' from '''IIT Bombay'''. Thank you for joining.
−
 
+
|-
 
|}
 
|}

Latest revision as of 12:14, 28 January 2020

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

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