PoojaMoolya: Created page with " {| border =1 ||'''Time''' ||'''Narration''' |- ||00:01 ||Welcome to this spoken tutorial on '''Buffer Solutions'''. |- || 00:05 ||In this tutorial we will learn, to p..."

2019-01-30T10:43:14Z

Created page with " {| border =1 ||'''Time''' ||'''Narration''' |- ||00:01 ||Welcome to this spoken tutorial on '''Buffer Solutions'''. |- || 00:05 ||In this tutorial we will learn, to p..."

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

|-
||00:01
||Welcome to this spoken tutorial on '''Buffer Solutions'''.

|-
|| 00:05
||In this tutorial we will learn, to prepare 0.5 M '''Acetate buffer''' of pH 3.6 and

test the buffering action with small amounts of acid and base.

|-
||00:18
||To follow this tutorial you should be familiar with, '''ChemCollective Vlabs interface'''.

|-
||00:25
||If not, for relevant tutorials please visit our website.

|-
||00:30
||Here I am using

Mac OS version 10.10.5

ChemCollective Vlabs version 2.1.0

|-
||00:39
||Java version 8.0.

|-
||00:41
||Here I have opened '''Virtual Chemistry Labs''' application window.

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||00:46
||Click on '''File''' menu, and select '''Load homework''' option.

'''Default Lab setup''' dialog box opens.

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||00:55
||Double-click on '''Acids and Bases''' folder.

Click on '''Buffer Creation Problem'''.
|-
||01:02
||The required chemicals for this experiment are provided in the '''Stockroom Explorer'''.

Let me demonstrate how to make '''Acetate buffer''' solution.

|-
||01:12
||A '''buffer solution''', is composed of a weak acid or weak base and its '''conjugate salt'''.

|-
||01:19
||Its pH changes very little when a small amount of acid or base is added to it.

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||01:26
||'''Henderson–Hasselbalch''' equation is useful for estimating the pH of a buffer solution.

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||01:33
||Please refer to the excellent tutorial on buffers at the following link.

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||01:38
||To prepare '''Acetate buffer''' of a particular '''pH''', '''Acetic acid''' and '''Sodium acetate''' are mixed in various proportions.

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||01:46
||To prepare 50 ml of '''pH 3.6 Acetate buffer'''-

We have to mix 46.3 ml of 0.1 M '''Acetic acid''' and 3.7 ml of '''Sodium acetate'''.

|-
||02:01
||Back to the '''Workbench'''.

Let us retrieve the chemicals and apparatus required for this experiment.

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||02:09
||From the '''Stockroom Explorer''' click on '''water''', 1M '''Sodium acetate''' and 1M '''Acetic acid'''.

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||02:18
||From '''Glassware cabinet''' retrieve, '''250 ml Erlenmeyer flask, 50 ml graduated cylinder'''.

|-
||02:28
||Make the duplicates of all the apparatus.

Rename '''graduated cylinders''' as G1 and G2.

|-
|| 02:39
||Rename '''Erlenmeyer flasks''' as A1 and A2.

|-
||02:46
||Let us prepare 0.5 M '''Acetic acid''' by diluting '''1 M Acetic acid'''.

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||02:53
||Measure 50 ml of Acetic acid in the graduated cylinder G1.

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||03:02
||Pour the contents of the '''graduated cylinder G1''' into '''Erlenmeyer flask A1'''.

|-
||03:11
||Measure 50 ml of water using the same '''graduated cylinder'''.

|-
||03:18
||Pour water into '''Erlenmeyer flask A1'''.

|-
||03:24
||Click on flask '''A1''' and note the '''pH'''.

It shows a pH of '2.53''.

|-
||03:32
||Similarly prepare 0.5 M '''Sodium acetate''' solution.

|-
||03:38
||Measure 50 ml of 1M '''Sodium acetate''' solution in '''graduated cylinder G2'''.

|-
||03:47
||Transfer this solution into '''Erlenmeyer flask A2'''.

|-
||03:54
||Measure 50 ml of water using the same '''graduated cylinder'''.

|-
||04:01
||Pour water from '''graduated cylinder''' into '''Erlenmeyer flask A2'''.

|-
||04:08
||Click on flask A2, note the pH.

It shows a pH of 9.23.

|-
||04:16
||We now have 0.5 M of '''Acetic acid''' and 0.5 M '''Sodium acetate''' solutions.

|-
||04:23
||Retrieve a '''250 ml beaker''' from the '''glassware cabinet'''.

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||04:28
||Transfer 46.3 ml of 0.5 M '''Acetic acid''' into the beaker.

|-
||04:35
||Bring flask A1 over to the beaker.

|-
||04:39
||Type 46.3 in the '''Transfer amount''' input bar.

Click on Pour.

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||04:46
||Transfer 3.7ml of 0.5 M '''Sodium Acetate''' into the beaker.

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||04:53
||Bring flask A2 over to the beaker.

|-
||04:56
||Type 3.7 in the '''Transfer amount''' input bar.

Click on Pour.

|-
||05:04
||Click on the beaker, check the pH in the '''PH Meter'''.

pH is shown as 3.66.

|-
||05:13
||We now have an '''acetate buffer''' solution of pH 3.66.

|-
||05:19
||Rename the beaker with buffer solution as '''Acetate buffer'''.

|-
||05:25
||Remove the used '''Erlenmeyer flasks''' and '''Graduates cylinders''' from the '''Workbench'''.

|-
||05:32
||To test the buffering action,

select '''water, hydrochloric acid(HCl)''' and '''1M sodium hydroxide(NaOH)''' from '''Stockroom Explorer'''.

|-
||05:43
||We will have to dilute, 1M hydrochloric acid(HCl) and 1M sodium hydroxide(NaOH) to 0.1 M hydrochloric acid(HCl) and 0.1 M sodium hydroxide(NaOH).

|-
||05:56
||Retrieve two sets of-

'''10 ml graduated cylinders'''

'''250 ml beakers'''

|-
|| 06:06
||'''Disposable pipettes''' from the '''glassware cabinet'''.

|-
|| 06:12
||Rename '''graduated cylinders''' as G1 and G2.

|-
||06:18
||Rename '''Beakers''' as A and B

|-
||06:22
||Rename '''Disposable pipette''' as P1 and P2.

|-
||06:28
||Measure 9 ml of water using '''graduated cylinder G1'''

Pour it in 250 ml '''Beaker A'''.

|-
||06:39
||Add 1 ml of 1M HCl to '''Beaker A''' using '''disposable pipette P1'''.

|-
|| 06:51
||0.1 M of hydrochloric acid(HCl) is ready for use.

|-
||06:57
||Similarly dilute 1M sodium hydroxide(NaOH) with water to prepare 0.1M sodium hydroxide(NaOH).

|-
|| 07:08
||Prepare 0.1 M sodium hydroxide(NaOH) in '''beaker B''', similarly as before.

|-
|| 07:18
||Diluted acid has a pH of 1.

Diluted base has a pH of 13.

|-
||07:25
||Let us add a small amount of acid to check the '''buffering action'''.

|-
||07:30
||Place the '''disposable pipette''' over the flask A.

|-
|| 07:34
||Withdraw 0.2 mL of HCl from flask A.

|-
|| 07:40
||Place the '''pipette''' over the beaker containing '''Acetate buffer'''.

|-
|| 07:45
||Pour 0.2 ml into '''buffer solution'''.

|-
||07:49
||Observe the change in pH. Notice that there is not much change in pH.

|-
||07:57
||Now add small amount of base to the '''buffer solution'''.

|-
|| 08:02
||Withdraw 0.2 ml of 0.1 M sodium hydroxide(NaOH) using '''disposable pipette'''.

|-
|| 08:09
||Place the '''pipette''' over the beaker containing '''buffer'''.

Pour 0.2 ml into '''buffer''' solution.

|-
||08:17
||Observe the '''pH Meter'''. Notice that there is no much change in the '''pH'''.

|-
|| 08:24
||Add acid and base to the buffer solution a few more times and check the '''pH'''.

|-
||08:47
||Let us summarize.

In this tutorial we have learnt to, Prepare 0.5 M Acetate buffer of pH 3.6.

|-
|| 08:57
||Tested buffering action with small amounts of hydrochloric acid(HCl) and sodium hydroxide(NaOH).

|-
||09:04
||As an assignment, Prepare pH 5.0 Acetate buffer and test with small amounts of acid and base.

|-
|| 09:13
||Hint: use 14.7 ml of 0.5 M Acetic acid and 35.3 ml of 0.5 M Sodium acetate.

|-
||09:24
||The video at the following link summarizes the Spoken Tutorial project.

Please download and watch it.

|-
||09:32
||The Spoken Tutorial Project team- conducts workshops using spoken tutorials and

gives certificates on passing online tests. For more details, please write to us.

|-
||09:43
||Please post your timed queries in this forum.

|-
||09:48
||Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.

More information on this mission is available at this link.

|-
|| 09:59
||This tutorial is contributed by Snehalatha kaliappan and Madhuri Ganapathi from IIT Bombay

Thank you for joining.
|-
|}

ChemCollective-Virtual-Labs/C2/Buffer-Solutions/English-timed - Revision history

PoojaMoolya: Created page with " {| border =1 ||'''Time''' ||'''Narration''' |- ||00:01 ||Welcome to this spoken tutorial on '''Buffer Solutions'''. |- || 00:05 ||In this tutorial we will learn, to p..."