Welcome to this tutorial on Density of Metals and Liquids using Vlabs.
In this tutorial, we will learn to determine, Densities of Metals and liquids.
To follow this tutorial you should be familiar with, ChemCollective Vlabs interface. If not, for relevant tutorials please visit our website.
Here I am using, Mac OS version 10.10.5 ChemCollective Vlabs version 2.1.0
Java version 8.
Here I have opened a Vlabs window.
Click on File menu and select Load homework option.
Select Molarity and Density from the list.
Double-click on Metals Density Problem from the sub-menu.
Go to Problem description in the Stockroom explorer.
Pause the video to read the problem and then resume again.
Problem states that you have 3 unlabeled bottles with metallic powder. You need to identify the metals in the bottles.
The metal densities are given in the problem description. We will use Archimedes' Principle to find the densities of metals.
An object when immersed in water will displace water. The displaced water will be equal to its volume.
Different metals have different densities. Hence, different metals of the same weight have different volumes.
A metal that is less dense will displace more water than a denser one.
Switch to Workbench
Double Click on Metal 1, Metal 2, Metal 3 to add them to the Workbench. Double click on water icon.
Click on Glassware icon. Select Graduated Cylinders.
From the sub-menu select 25 ml Graduated Cylinder.
We need three 25 ml Graduated Cylinders for this experiment.
Right-click on Graduated Cylinder.
Context menu opens. Using Duplicate option make 2 copies of the Graduated Cylinder.
Drag and bring the Graduated Cylinders to the centre of the Workbench.
Label the Cylinders as 1, 2 and 3.
Let us drag graduated cylinder 1 to the water tank.
Notice that a red warning icon appears.
This indicates that procedure is incorrect. Place graduated cylinder 1 aside.
The correct procedure is to drag water on to the graduated cylinder.
Change the transfer mode to Precise Transfer using Tools menu.
Type 10 in the Transfer amount input bar. Click on pour.
10 ml of water is transferred into the graduated cylinder 1.
Likewise transfer 10ml of water into graduated cylinders 2 and 3.
Move the water tank to a different place on the Workbench.
Click on Select Tools menu, from the list, select Scale.
Drag the Scale to a convenient position on the Workbench.
Again click on Select Tools menu, from the list select Weighing Boat.
We need three Weighing Boats for this experiment. We can also use short-cut keys, to copy and paste.
Click on Weighing Boat. Use Ctrl-C to copy and Ctrl-V to paste.
Drag and bring the weighing boats to the centre of the Workbench
Label the Weighing Boats as 1, 2 and 3.
Place weighing boat 1 over the scale. Click on TARE button on the scale.
Drag Metal 1 over to weighing boat 1.
Type 50 in the Transfer Amount(g) input bar Click on Pour. Place the bottle aside.
Remove the weighing boat from the scale. Place weighing boat 1 over the graduated cylinder 1.
Type 50 in the Transfer Amount input bar . Click on Pour.
Observe the level of water in the graduated cylinder. It has risen by 5 ml.
Keep the weighing boat 1 aside.
Now, Place weighing boat 2 on the scale. Click on TARE button on the scale.
Drag Metal 2 over weighing boat 2.
Type 50 in the Transfer Amount(g) input bar. Click on Pour.
Place the bottle aside.
Remove the weighing boat 2 from the scale. Place weighing boat 2 over the graduated cylinder 2.
Type 50 in the Transfer Amount(g)input bar. Click on Pour.
Observe that the water level in the cylinder has risen by 4 ml. Keep the weighing boat 2 aside.
Similarly, weigh 50 grams of metal 3 using weighing boat 3.
Place weighing boat 3 over the graduated cylinder.
Type 50 in the Transfer Amount(g) input bar. Click on Pour.
Water level in the cylinder has risen by 2.5 ml. Keep the weighing boat 3 aside.
This slide shows the density calculations for the metals. Calculate the densities using the formula: Density= mass/volume.
Experimental density of Metal 1 is 10 which corresponds to Silver.
Metal 2 is 12.2 which corresponds to Rhodium.
Metal 3 is 20 which corresponds to Platinum.
Repeat the above experiment with different metal weights (30 g and 40 g). Tabulate and analyse your results.
Lets proceed to the liquid density problem.
Let us add a new workbench. Click on File and select New workbench option.
Click on the workbench.
Go to File menu and select Load homework option.
Select Molarity and Density from the list.
Double-click on Liquid density problem.
Double-click on problem description in the stockroom explorer.
Pause the video to read the problem statement. Resume after reading.
The problem states that there are two compounds of A-1 and A-2.
One of the liquids is a preservative, other liquid is not a preservative. The preservative has higher density.
Our aim is to find the liquid containing Preservative. For this we need to measure densities of A-1 and A-2.
Switch back to Workbench
Double-click on compounds A-1 and A-2 to add them to Workbench.
Obtain a 100ml volumetric flask from the glassware option.
We need two 100ml volumetric flasks for this experiment.
We can make a copy using Duplicate option.
Drag and bring the flasks to the center of the workbench.
Label the flasks as A-1 and A-2. We can rename by pressing F2.
Click on Select tools icon. Select Scale and add it to the Workbench.
Place the volumetric flask A-1 on the scale. Click on TARE button.
Transfer 100ml of Compound A1 to flask A-1 by Precise Transfer mode.
Note the mass from the scale. Scale reads 126 g.
Note this value. Place the flask A-1 aside.
Remove Volumetric flask from the scale.
Next place flask A-2 on the scale, click on TARE. Pour 100 ml of Compound A-2.
Scale reads 85 g. Note this value.
Experimental results are tabulated on this slide. Calculate densities using the formula: Density=mass/volume
Observe that density of Compound A-1 is more than Compound A-2. Therefore Compound A-1 contains the preservative.
Let's summarize. In this tutorial we have learnt to measure, Densities of silver, rhodium and platinum using Archimedes' Principle.
Densities of liquids with unknown concentration.
For the assignment. Open default lab setup window.
You will find many stock solutions. Find density for a few solutions of your choice.
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This tutorial is contributed by Snehalatha Kaliappan and Madhuri Ganapathi from IIT-Bombay. Thank you for joining