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