ChemCollective-Virtual-Labs/C2/Acid-base-Titrations/English-timed

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Time Narration
00:01 Welcome to this spoken tutorial on Acid-Base Titrations using Vlabs.
00:07 In this tutorial we will learn to standardise:

Strong-Acid with Strong-Base and

Strong-Acid with Weak-Base

using titration method.

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

00:35 ChemCollective Vlabs version 2.1.0

Java version 8.0.

00:43 Here I have opened Virtual Chemistry labs application window.

Default lab setup window opens.

00:51 Let us begin the demonstration with standardization of strong acid with strong base.
00:59 We will retrieve required chemicals from stockroom.

Double-click on Strong-acids cabinet.

01:09 Now double click to Select, 0.1 Molar Hydrochloric acid from the list.

Close the cabinet.

01:18 From the Strong-bases cabinet, select, 0.1 Molar sodium hydroxide.

Close the cabinet.

01:26 From the Indicators cabinet select Phenolphthalein.
01:30 Drag the bottle and drop on the workbench.

Close the cabinet.

01:36 Click on Glassware menu.

Now select, 250 mL Erlenmeyer Flask.

01:43 10 mL Pipet and 50 mL Buret.

Rearrange the apparatus.

01:51 Rename the Erlenmeyer Flask as A1.
01:55 Using pipet transfer 20 mL of Hydrochloric acid(HCl) into flask A1.
02:02 Place the 10 mL pipet on flask containing Hydrochloric acid(HCl).
02:08 In the Transfer Amount input-bar type 10.

Click on Withdraw.

02:15 Drag the Pipet on to flask A1.
02:19 In the Transfer Amount input-bar type 10.

Click on Pour.

02:25 We require 20 mL of HCl for this titration.
02:30 Since we have 10 mL pipet we need to use it twice to transfer 20 mL of Hydrochloric acid(HCl).
02:40 Place Phenolphthalein bottle over Flask A1.
02:44 Type 0.3 in the Transfer Amount input bar.

Click on pour.

02:51 Keep Phenolphthalein bottle and Hydrochloric acid(HCl) aside.
02:56 Drag and place 0.1 Molar Sodium hydroxide(NaOH) over the burete.
03:02 Transfer 50 mL of Sodium hydroxide(NaOH) into the buret.

Observe that, burete reading is not zero.

03:11 This is because the lower part of the burete is also filled.

Keep Sodium hydroxide(NaOH) flask aside.

03:19 Place the burete over Flask A1.

Click on the buret.

03:25 Note the initial volume of Sodium hydroxide(NaOH) in the buret from the Solution Info panel.
03:32 Change the Transfer Bar to Realistic Transfer.

Click on Pour button gradually.

03:40 Reaction between Hydrochloric acid(HCl) and Sodium hydroxide(NaOH) is equimolar.
03:46 So, end point is expected around 20 mL.
03:51 To obtain accurate volume for end-point detection; After adding 19 mL of Sodium hydroxide(NaOH), change the Transfer Bar to Significant Figures Transfer.
04:05 In the Transfer Amount input bar type 0.01.
04:10 This will transfer 0.01 mL of Sodium hydroxide(NaOH) for every click on the pour button.
04:18 Observe the pH change in the Solution Info panel.
04:22 Click on pour button, observe the faint pink colour in Flask A1.

This is the end-point of titration.

04:33 Click on the buret.

Note the volume of remaining Sodium hydroxide(NaOH) from the solution info panel.

04:41 Final calculations are shown on this slide.
04:45 We have used the formula M1V1= M2V2 to calculate M1 that is molarity of Hydrochloric acid(HCl).
04:54 We have obtained the value of M1 as 0.1 M.
04:59 To clear the workbench, select each component .
05:03 To remove the selected component, click on remove tool.
05:07 Similarly remove all the components from the workbench.
05:12 Let us retrieve solutions for the titration of Strong-acid with Weak-base.
05:18 Double-click on Strong-acids cabinet and select 1 Molar Hydrochloric acid(HCl). .
05:24 Now double click on Weak-bases cabinet and select 1 Molar Ammonia.
05:33 For this experiment let us choose methyl orange as indicator.
05:38 Drag and place it on the workbench.
05:42 Double-click on Glassware menu.

Select the following glassware;

05:48 250 mL Erlenmeyer Flask.

10 mL Pipet and 50 mL Buret.

05:57 Rearrange the apparatus.
06:00 Rename the Erlenmeyer Flask as A2.
06:04 Change the Transfer Bar to precise transfer.
06:08 Using pipet transfer 20 mL of Ammonia into flask A2.
06:15 Place 10 mL pipet on flask containing Ammonia.
06:20 In the Transfer Amount input-bar type 10.

Click on Withdraw.

06:26 Drag the Pipet on to flask A2.
06:30 In the Transfer Amount input-bar type 10.

Click on Pour.

06:36 We need 20 mL of Ammonia, so pipette out twice into flask A2.
06:50 Transfer 0.3 mL of methyl orange into flask A2.

Keep methyl orange bottle aside.

07:00 Drag and place 1 M Hydrochloric acid over the buret.
07:05 Transfer 50 mL of Hydrochloric acid into the buret.
07:13 Place the buret over flask A2.
07:17 Let us start the titration.
07:20 Change the Transfer Bar to Realistic Transfer.

Click on Pour button gradually.

07:27 Reaction between Hydrochloric acid(HCl) and ammonia is equimolar.

So, end point is expected around 20 mL.

07:36 To obtain accurate volume for end-point detection;

After adding 19 mL of Hydrochloric acid, change the Transfer Bar to Significant Figures Transfer.

07:49 In the transfer amount input bar type 0.01. Click on Pour
07:57 This will transfer 0.01 mL of Hydrochloric acid(HCl) for every click on pour button.
08:05 As we titrate observe the increase in temperature.
08:09 Observe the pH changes.
08:12 Transfer a few more drops of Hydrochloric acid(HCl).

Observe the change in colour in Flask A2 to orange colour.

08:21 Note the final volume of Hydrochloric acid(HCl) from the Solution info panel.
08:27 Your final volume may be different from the value shown here.
08:32 Click on Spectrometer radio button.

Note the Absorbance in the Solution info panel.

08:40 Here are the final calculations.

Molarity of ammonia is 1M.

08:47 Let us summarize . In this tutorial we have learnt to standardise;

Strong-Acid with Strong-Base and

Strong-Acid with Weak-Base

using titration method.

09:00 As an assignment,

Standardize a solution of ethanoic acid (acetic acid) using titration method.

09:07 Hint- All the necessary solutions and apparatus are available in default lab setup window.
09:15 The video at the following link summarizes the Spoken Tutorial project.

Please download and watch it.

09:22 The Spoken Tutorial Project team-

conducts workshops using spoken tutorials and

gives certificates on passing online tests.

For more details, please write to us.

09:34 Please post your timed queries on this forum.
09:39 Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.

More information on this mission is available at this link.

09:50 This tutorial is contributed by Snehalatha Kaliappan and Madhuri Ganapathi from IIT-Bombay.

Thank you for joining.

Contributors and Content Editors

PoojaMoolya