PoojaMoolya at 10:35, 28 October 2020

2020-10-28T10:35:43Z

PoojaMoolya: Created page with "{| border=1 || '''Time''' || '''Narration''' |- || 00:01 || Welcome to this tutorial on '''Determination of Equilibrium Constant''' using '''Vlabs'''. |- || 00:08 || I..."

2019-01-30T11:12:27Z

Created page with "{| border=1 || '''Time''' || '''Narration''' |- || 00:01 || Welcome to this tutorial on '''Determination of Equilibrium Constant''' using '''Vlabs'''. |- || 00:08 || I..."

New page

{| border=1
|| '''Time'''
|| '''Narration'''

|-
|| 00:01
|| Welcome to this tutorial on '''Determination of Equilibrium Constant''' using '''Vlabs'''.

|-
|| 00:08
|| In this tutorial, we will learn, To determine equilibrium constant for Cobalt chloride reaction.

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|| 00:15
|| Observe the effect of change in temperature and concentration on equilibrium.

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||00:22
||To follow this tutorial, you should be familiar with, '''ChemCollective Vlabs interface'''.

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|| 00:29
|| If not for relevant tutorials please visit our website.

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||00:34
|| Here I am using,

'''Mac OS''' version 10.10.5

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|| 00:39
|| '''ChemCollective virtual labs''' version 2.1.03

'''Java''' version 8.

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||00:48
||Here I have opened '''Vlabs''' interface.

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||00:52
||Click on '''File''' menu. Scroll down to '''Load Homework''' option.

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|| 00:57
|| '''Default Lab Setup''' dialogue-box opens.

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||01:02
||From the list, double-click on '''Chemical Equilibrium'''.

Two options appear.

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|| 01:10
|| Double-click on '''Cobalt Lab''' option.

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||01:14
||'''Stockroom Explorer''' has required solutions and '''Problem Description'''.

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||01:20
||Double-click on '''Problem Description'''.

Problem description states that, we need to apply '''Le Chatelier's principle''', for aqueous '''Cobalt chloride''' reaction.

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|| 01:33
||Using the equilibrium concentration we need to find, equilibrium constant for cobalt chloride reaction and

Effect of temperature and reactant concentration on equilibrium.

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|| 01:47
||Let us define chemical equilibrium.

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|| 01:50
|| '''Chemical equilibrium''' is a state of the reversible reaction when two opposing reactions occur at the same rate.

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|| 01:59
||Concentration of the reactants and products do not change with time at equilibrium.

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||02:06
|| This side shows a general '''Equilibrium Reaction'''.

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|| 02:11
|| This is the equation for '''Equilibrium Constant'''.

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|| 02:15
|| The chemical equation for this reaction is shown here.

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|| 02:20
|| Cobalt forms complexes with water molecules, as well as chloride ions.

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|| 02:27
|| A solution of '''Hexaaquacobalt(II)complex''' is pink.

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|| 02:33
|| When hydrochloric acid is added to the solution, the colour changes to blue.

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|| 02:39
|| This corresponds to the formation of '''Cobalt Chloride complex'''.

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||02:44
|| Equilibrium Constant changes with, Change in concentration of reactants or products and

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|| 02:51
|| Change in temperature.

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||02:54
|| Click on '''Workbench'''.

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|| 02:57
|| Double-click on '''Cobalt chloride experiment solutions''' cabinet.

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|| 03:03
|| Double-Click on '''1M Cobalt Chloride.'''

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|| 03:07
|| A flask with '''100 mL''' of '''1M Cobalt Chloride''' is added to the workbench.

Observe the colour of the solution in the flask.

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|| 03:18
|| '''Solution Info''' panel shows the required information.

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|| 03:23
|| Colour of the solution is pink due to presence of '''Hexaaquacobalt(II)complex'''.

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|| 03:30
||Note the concentrations of '''Hexaaquacobalt(II)complex''', '''chloride ions''' and '''Cobalt chloride''' in your observation book.

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|| 03:40
|| Double-Click on '''12 M HydroCloric acid'''.

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|| 03:44
|| Click on '''Glassware '''menu. Select '''Erlenmeyers'''.

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|| 03:50
|| From the list click on 250 mL '''Erlenmeyer''' flask.

Rename the flask as '''A'''.

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|| 03:59
|| From the '''Glassware''' menu, select '''Pipets'''.

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|| 04:03
|| From the list, click on 25 mL '''Pipet'''.

From the '''Glassware''' menu, select 50 mL '''Buret'''.

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|| 04:12
|| Using '''Pipet''', measure 25 mL of '''Cobalt chloride''' solution.

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|| 04:18
|| Click on '''Withdraw'''.

Keep the flask aside.

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|| 04:23
|| Place the''' Pipet''' over '''flask A'''.

Type '''25''' and Click on '''Pour'''.

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|| 04:31
|| Keep the '''Pipet''' aside.

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|| 04:34
|| Fill the '''buret''' with 50 ml of '''12 M hydrochloric acid'''.

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|| 04:40
|| Bring '''12 M hydrochloric acid''' flask on to 50 mL '''buret'''.

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|| 04:46
|| Type 50 in the '''Transfer amount''' input bar.

Click on '''Pour'''.

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|| 04:52
|| Keep the flask aside.

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|| 04:55
|| Bring the '''buret''' on to '''flask A'''.

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|| 04:58
|| Add hydrochloric acid from the '''burette''' in 1 mL increments, using '''Precise Transfer''' mode.

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|| 05:07
|| Type 1 in the '''Transfer amount''' input bar and click on '''Pour'''.

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|| 05:13
|| Similarly transfer another 6 mL of hydrochloric acid using '''Precise Transfer''' mode.

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|| 05:22
|| We have transferred 7 mL of hydrochloric acid to '''Flask A'''.

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||05:28
|| Notice the change in temperature on the thermometer.

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|| 05:33
|| Temperature decreases during the reaction.

It means that, the reaction is '''endothermic'''.

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|| 05:41
|| The total volume of solution in '''Flask A''' shows 32 mL.

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|| 05:47
|| Observe the colour change in '''Flask A''', colour changes to brown.

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|| 05:53
|| It may take a few seconds to reach equilibrium state.

Now the concentrations of the reactants and products are constant.

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|| 06:03
||Note the values of the concentrations of '''Hexaaquacobalt(II)complex''', '''chloride ions ''' and '''cobalt chloride ''' in your observation book.

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|| 06:14
|| Continue the titration.

Pour 1 mL at a time into the flask.

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|| 06:21
|| Transfer another 8 mL of Hydrochloric acid to '''flask A'''.

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|| 06:27
|| Now we have transferred 15 mL of hydrochloric acid to '''flask A'''.

Total volume of liquid in '''flask A '''is 40 mL

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|| 06:40
|| Note the colour change in '''Flask A'''.

Please wait for the reaction to reach equilibrium condition.

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||06:49
|| Again note the concentrations of '''Hexaaquacobalt(II)complex''', '''chloride ions''' and '''cobalt chloride''' in your observation book.

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|| 07:00
|| Similarly add another 3 ml of hydrochloric acid to '''flask A'''.

Total volume in '''flask A''' is 43 mL.

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|| 07:11
|| Note the colour change in '''flask A'''.

Note the concentrations in your observation book.

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|| 07:19
|| Finally add 5 mL of hydrochloric acid''' from the ''' buret'''.

Total volume in '''flask A''' is now 48 mL.

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|| 07:30
|| Note that we have added 23 mL of hydrochloric acid to '''flask A'''.

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|| 07:37
|| Colour of the solution in '''flask A''' is blue.

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|| 07:41
|| Again note the concentrations of '''Hexaaquacobalt(II)complex''', '''chloride ions''' and '''cobalt chloride''' at equilibrium in your observation book.

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|| 07:52
|| Let us see how to calculate '''Equilibrium Constant'''.

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|| 07:56
|| Calculate '''Equilibrium Constant''' using the given formula.

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|| 08:01
|| Substitute the values of concentrations of '''cobalt chloride''', '''Hexaaquacobalt(II)complex''' and '''chloride ions''' in the equation.

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|| 08:11
|| This is the value of equilibrium constant after pouring 7 mL of '''hydrochloric acid'''.

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|| 08:19
|| Similarly, here are the values of equilibrium constant for 15, 18 and 23 mL of hydrochloric acid.

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|| 08:29
|| Since, temperature is constant, equilibrium constant values are almost the same.

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|| 08:36
|| Switch to '''workbench'''.

Next I will demonstrate the effect of temperature on equilibrium.

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|| 08:45
|| Earlier we have observed that, this reaction is '''endothermic'''.

It means, heat is absorbed during the reaction.

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|| 08:54
|| '''Le Chatelier’s '''Principle states that,

If an equilibrium is disturbed by changing the conditions, position of equilibrium moves to counteract the change.

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|| 09:06
|| According to the principle, for endothermic reactions, rate of forward reaction increases with increase in temperature.

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|| 09:14
|| Back to '''workbench'''. Keep the burette aside.

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||09:20
|| Let us increase the temperature of the reaction flask to '''35 degree Celcius.'''

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|| 09:26
|| Right-click on flask '''A''', from the context menu, select '''Thermal Properties'''.

Input box opens.

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|| 09:35
|| In '''Set the temperature to''' text box, type '''35'''.

Check the box for '''Insulated from surroundings'''.

Click on '''OK'''.

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|| 09:46
|| Thermometer shows '''35 degree Celcius.'''

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||09:50
|| Note the values of concentrations of '''Hexaaquacobalt(II)complex''', '''Chloride ions''' and '''Cobalt Chloride'''.

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||09:59
|| This is the calculated value of equilibrium constant at '''35 degree Celcius'''.

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||10:05
|| Compare it to equilibrium constant value with that at '''25 degree Celcius'''.

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|| 10:12
|| Note that the value of '''Kc''' at '''35 degree Celcius ''' is greater than '''Kc value''' at '''25 degree Celcius'''.

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|| 10:21
|| This is because the reaction is an endothermic reaction.

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|| 10:26
||As the temperature increases rate of forward reaction increases.

Hence more product is formed.

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|| 10:34
|| Switch to '''workbench''',

Remove the used '''pipette''' and '''burette''' from the''' Workbench'''.

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||10:42
|| Right-click on flask '''A'''

From the context menu, select '''Thermal Properties'''.

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|| 10:49
|| Un-check the box for '''Insulated from surroundings'''.

Click '''OK'''.

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|| 10:55
||This will bring the temperature back to 25 degree Celcius.

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|| 11:00
|| Now let us remove the chloride ions from the reaction using '''Silver Nitrate'''.

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|| 11:07
|| Double-Click on '''6M Silver nitrate''' from '''Stockroom Explorer'''.

From the '''glassware''' menu, select 25 mL '''Pipet'''.

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|| 11:18
|| Withdraw 25 mL of '''silver nitrate'''(AgNO3 ) into the 25 mL '''Pipet'''.

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|| 11:26
|| Transfer 25 mL of '''silver nitrate(AgNO3) from '''pipet''' to '''flask A''' in 5 mL increments.

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|| 11:34
||Type 5 in '''Transfer Amount input bar'''.

Click on Pour.

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|| 11:40
|| Note the temperature. It increases as you add '''silver nitrate''' to flask A.

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|| 12:00
||Note the colour change.

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|| 12:02
|| It indicates the formation of '''Hexaaquacobalt(II)complex'''.

Click on '''Solid''' radio button.

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|| 12:11
||Note the amount of '''silver chloride(AgCl)''' in '''grams''' column.

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|| 12:16
|| '''Silver nitrate(AgNO3)''' reacts with '''chloride(Cl-) ions in solution to form '''silver chloride(AgCl)'''.

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|| 12:23
|| Here chloride(Cl-) ions decrease in the solution, to compensate for the deficit,

Rate of reverse reaction increases.

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|| 12:33
|| Cobalt chloride complex decomposes to form '''HexaaquaCobalt(II)''' complex.

This example is a proof for '''LeChatelier's''' principle.

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|| 12:44
|| Let us summarize.

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||12:46
|| In this tutorial, we have learnt, To determine '''equilibrium constant''' for Cobalt chloride reaction.

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|| 12:53
|| Observe the effect of change in temperature and concentration on equilibrium.

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|| 12:59
|| As an assignment,

Prepare a solution by adding 25 mL of Cobalt chloride solution and 23 mL of Hydrochloric acid.

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|| 13:09
|| Add 40 mL of water in 10 mL increments to the prepared solution

Observe the colour in the flask.

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|| 13:19
|| Calculate Equilibrium Constant before and after addition of water.

|-
|| 13:25
|| The video at the following link summarizes the Spoken Tutorial project.

Please download and watch it.

|-
|| 13:33
|| The '''Spoken Tutorial Project '''team, conducts workshops using spoken tutorials and

gives certificates on passing online tests.

For more details, please write to us.

|-
|| 13:45
|| Please post your timed queries on this forum.

|-
|| 13:49
|| Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.

More information on this mission is available at this link.

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|| 14:00
|| This tutorial is contributed by '''Snehalatha kaliappan ''' and '''Madhuri Ganapathi''' from '''IIT Bombay'''.

Thank you for joining.
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|}

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-|| '''Default Lab Setup''' dialogue-box opens.
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ChemCollective-Virtual-Labs/C3/Determination-of-Equilibrium-constant/English-timed - Revision history

PoojaMoolya at 10:35, 28 October 2020

PoojaMoolya: Created page with "{| border=1 || '''Time''' || '''Narration''' |- || 00:01 || Welcome to this tutorial on '''Determination of Equilibrium Constant''' using '''Vlabs'''. |- || 00:08 || I..."