# Chemteacher

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# Virtual Lab Demo Movie

So, you are confused by the virtual lab? Don’t like reading the step-by-step instructions? Here is a brief video to help you along your way in the lab assignments:

• I completed the tasks quickly in order to show you how to do the tasks in a short video. You would take MUCH MORE TIME to complete your task. It takes time to slowly reach the magical end point.
• I added way too much base (NaOH) too quickly in the final part of the procedure. You can see this beacuse it turned bright red, and not faint pink. In order to get the best results you would need to add the base slowly so that the color is pink, stopping after the first appearance of faint pink.
• Yes, you must use burets: that way you can get volumes to the nearest 0.01 mL (more SF!). This is a way to emulate a REAL LAB so please treat it that way. (No, I’m not joking)
• When you do each lab, you should should perform a few trials, and this video shows only ONE TRIAL. You must create a REAL DATA TABLE, just as if you had done this in the lab showing all of the data collected.
• And finally, these exact instructions are typed into the problem description in the virtual lab – really – take a look. When you take short cuts I am guessing that you are guaranteed to be confused.

Sample Lab (NOTE – this data was not recorded during the video above)

I. Purpose

The purpose of this lab is to determine the concentration of the NaOH solution.

II. Data

Lab reaction:
KHP (aq) + NaOH (aq) –> NaKP (aq) + H2O (L)

The concentration of the KHP solution = 0.500 M

III. Calculations

A. Volume of Solution
v = v2 – v1
32.54 mL = 39.85 mL – 7.31 mL

B. Moles NaOH
moles = Vol KHP (moles KHP/L)(1 mole NaOH/1 mole KHP)
0.01627 moles = (32.54 mL)(1 L / 103 mL)(0.500 moles KHP/L)(1 mole NaOH/1 mole KHP)

C. Concentration of NaOH
M = moles NaOH / V NaOH
0.944 M = 0.01627 moles NaOH/ [(17.23 mL)(1 L / 103 mL)

D. Average Concentration
M avg = (M1 + M2 + M3)/3
0.943 M = (0.944 M + 0.946 M = 00.940M)/3

All of the calculations from the lab are summarized here

IV. Conclusion

The concentration of the NaOH solution is 0.943 M

### 3 comments on “Virtual Lab Demo Movie”

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