ChemCollective-Virtual-Labs/C3/Heat-of-Reaction/English-timed
From Script | Spoken-Tutorial
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| Time | Narration |
| 00:01 | Welcome to this spoken tutorial Heat of Reaction using Vlabs. |
| 00:06 | In this tutorial, we will learn to, Determine heat change for the neutralisation of Sodium hydroxide (NaOH) and Hydrochloric acid(HCl). |
| 00:16 | Calculate heat of reaction for three different reactions. |
| 00:21 | The three reactions are shown here. |
| 00:25 | To follow this tutorial you should be familiar with, ChemCollective Vlabs interface. |
| 00:32 | If not, for relevant tutorials please visit our website. |
| 00:38 | Here, I am using Mac OS 10.10.5 |
| 00:44 | ChemCollective Vlabs version 2.1.0
Java version 8. |
| 00:52 | I have opened a Virtual Chemistry lab application window. |
| 00:57 | Click on File and select Load homework option. |
| 01:03 | Default Lab setup dialog box opens. |
| 01:08 | In the box, select Thermochemistry. |
| 01:12 | Double click on Heats of the reaction- Hess’s Law option. |
| 01:17 | Click on Problem Description in Stockroom Explorer. |
| 01:22 | The Problem Descriptionhere states that, we have to determine and compare heat of reaction for 3 different reactions. |
| 01:31 | Scroll down the page and read, Procedure, Processing the data, Discussion and Conclusion |
| 01:42 | This experiment is an illustration of Hess's law. |
| 01:46 | Which states that , total heat change during the complete course of a reaction is same,
whether the reaction is made in one step or in several steps. |
| 01:59 | Heat of reaction is also known as Standard enthalpy change. |
| 02:04 | delta rH = delta r H 1 + delta r H 2 + delta r H 3 ,etc. |
| 02:13 | Sum of Heats of reactions for, Reaction 1 and Reaction 3 must be equal to heat of reaction for Reaction 2. |
| 02:22 | Let us go back to Workbench.
We will begin the first reaction. |
| 02:28 | Let us select the required chemicals and apparatus for the reaction. |
| 02:34 | From the Chemical Stockroom, Double-click on Distilled water. |
| 02:39 | Click on Solids cabinet and double-click on Sodium hydroxide.
Close the cabinet. |
| 02:47 | From the glassware menu, we will select a 50 mL Graduated Cylinder and a Foam Cup. |
| 02:56 | From the instrument menu, select Weighing Boat and a Scale. |
| 03:02 | Transfer 50 mL of Distilled water to the Graduated Cylinder. |
| 03:08 | In the Transfer amount input bar, type 50 and click on Pour. |
| 03:15 | Weigh 1 gram of Sodium hydroxide using Weighing Boat. |
| 03:21 | Place the Weighing Boat on the Scale, click on TARE. |
| 03:27 | Drag the Sodium hydroxide bottle over the weighing boat. |
| 03:32 | Type 1 in the Transfer amount input bar and click on Pour . |
| 03:39 | Transfer Sodium hydroxide from Weighing Boat to Foam Cup.
Click on Pour. |
| 03:47 | Click on Foam Cup.
In the Solution info panel, Click on Solid radio button and observe the weight in grams column. |
| 03:58 | Click on the Graduated Cylinder and record its temperature.
Thermometer shows the temperature as 25 degrees Celsius. |
| 04:08 | Drag the Graduated Cylinder over to the Foam Cup.
Type 50 in the Transfer Amount input bar and click on Pour. |
| 04:21 | Click on Foam Cup.
Record the highest temperature on the thermometer. |
| 04:27 | Thermometer shows 30.29 degrees Celsius. |
| 04:32 | Observe the grams column, it shows zero.
This is because all the Sodium hydroxide has now dissolved in water. |
| 04:42 | Lets see how to calculate heat of the reaction. |
| 04:46 | Heat of reaction (q) is calculated using the formula.
q = m * s * ∆T wherein 'm' is mass of the reactants |
| 04:57 | 's' is the specific heat of the product and
'∆T' is the change in temperature in the reaction. |
| 05:05 | Heat energy calculation for this reaction is given here. |
| 05:11 | Calculation of Molar Heat energy (delta H) in Kilo Joules per mol is given here. |
| 05:18 | delta H for reaction 1 Sodium hydroxide is -45.32 Kilo Joules per mol |
| 05:26 | Lets go back to workbench.
Let us delete the used Graduated Cylinder and Foam Cup. |
| 05:34 | We will now move on to demonstrate second exothermic reaction. |
| 05:40 | From Glassware menu, Take a new 50 mL Graduated Cylinder and a Foam Cup. |
| 05:49 | From the Chemical Stockroom, select Strong-acids cabinet.
Double click to get 0.5 M Hydrochloric acid. |
| 05:59 | Close the Cabinet. |
| 06:01 | Transfer 50 mL of Hydrochloric acid into the Graduated Cylinder. |
| 06:08 | Weigh 1 gram of Sodium hydroxide using Weighing Boat. |
| 06:15 | Transfer Sodium hydroxide from Weighing Boat to Foam Cup. |
| 06:21 | Click on the Graduated Cylinder, record its temperature. |
| 06:27 | Pour the contents of the Graduated Cylinder into the Foam Cup. |
| 06:33 | Click on the Foam Cup.
Record the highest temperature on the thermometer. |
| 06:39 | Thermometer shows 36.96 degree Celcius. |
| 06:45 | Calculation of Molar Heat energy (delta H) in Kilo Joules per mol is given here. |
| 06:51 | delta H for Reaction 2 is -102.47 Kilo Joules per mol |
| 07:00 | Delete the used apparatus and chemicals from the Workbench. |
| 07:06 | From Glassware menu take a new 25 mL Graduated Cylinder and a Foam Cup |
| 07:14 | We need two Graduated Cylinders.
Use Duplicate option in the context menu to make the copies. |
| 07:22 | Drag both the cylinders to a convenient place on the Workbench. |
| 07:27 | Label the cylinders as A and B. |
| 07:35 | From the Chemical Stockroom click on Strong-acids cabinet.
Double click on 1.0 M Hydrochloric acid. |
| 07:44 | Close the cabinet.
From the Strong-bases cabinet, double click on 1.0 M Sodium hydroxide. |
| 07:52 | Close the cabinet. |
| 07:54 | Transfer 25 mL of Hydrochloric acid(HCl) into graduated cylinder A. |
| 08:01 | Pour the Hydrochloric acid(HCl) from graduated cylinder to Foam Cup. |
| 08:07 | Note the temperature on the thermometer. |
| 08:11 | Measure 25 mL of Sodium hydroxide in Graduated Cylinder B. |
| 08:18 | Pour the measured Sodium hydroxide into the Foam Cup. |
| 08:24 | Click on Foam Cup.
Allow the reaction to take place for a few seconds. |
| 08:31 | Record the highest temperature. Thermometer shows 31.67 degree Celcius. |
| 08:40 | Calculation of Molar Heat energy for reaction three is given here.
delta H for reaction 3( Rx3) is -56.03 Kilo Joules per mol |
| 08:53 | Now, Let us now analyze the results.
The value of Sum of heats of reactions for Reaction 1 and Reaction 3 is -101.35 Kilo Joules per mol |
| 09:07 | The value of heat of reaction for Reaction 2 is -102.47 Kilo Joules per mol.
Therefore this experiment illustrates Hess's law. |
| 09:21 | Let us summarize. |
| 09:23 | In this tutorial we have, Determined heat change for neutralization of Sodium hydroxide
and Hydrochloric acid. |
| 09:32 | Calculated heat of reaction for 3 different reactions. |
| 09:37 | For the assignment, Explain why the reactions are exothermic. |
| 09:42 | Repeat Reaction 1 using 4 grams of Sodium hydroxide and calculate the heat of reaction. |
| 09:51 | Compare its value with the reaction in which 1 gram of Sodium hydroxide was used. |
| 09:58 | The video at the following link summarizes the Spoken Tutorial project.
Please download and watch it. |
| 10:06 | The Spoken Tutorial Project team: conducts workshops using spoken tutorials and
gives certificates on passing online tests. For more details, please write to us. |
| 10:18 | Please post your timed queries in this forum. |
| 10:22 | Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.
More information on this mission is available at this link. |
| 10:34 | This tutorial is contributed by Snehalatha kaliappan and Madhuri Ganapathi from IIT Bombay.
Thank you for joining. |
