Virtual Experiment 10

Electrolytes and Electrical Conductivity

The Virtual Experiment 10 laboratory assignment was performed by Dr A. Sullivan. To complete this laboratory assignment, you can view the video of the laboratory experiment below. The video will be used to observe and record the data for this laboratory assignment

The assignments that must be completed are:

Complete the pre laboratory quiz in Canvas before coming to the class meeting.
Use the videos and simulation to make observations and record the appropriate data for each part of the laboratory report. Complete all questions in the Laboratory Report.

Experiment 10

Virtual Experiment10

Chapter 9 Electrolytes.mp4

This presentation talks about electrolytes

Discussion

Electrical charge is able to move through substances when electrons or ionic charge is mobile and flows through the substance. Metallic substances have delocalized electrons that are able to move freely through the materials allowing a current to flow. Substances that conduct electricity freely are called conductors, while substances that impede the flow of electrons are called insulators. Substances with covalent bonds generally have electrons that are localized in the bond and therefore are not free to flow.

A detailed discussion is available on the Experiment 10 website.

Pre laboratory assignment

The pre laboratory problems are questions about the laboratory assignment, background, definitions or procedure and calculations. These problems should be completed BEFORE coming to the class where the assignment will be discussed. The pre laboratory problems for this experiment should be completed as a quiz in Canvas.

Pre lab Virtual Experiment10

Procedure

The laboratory report of the assignment contains questions, data collection, calculation and reporting of results.

Use the following videos to complete the laboratory assignment.

V-Experiment10 Report

Part A - Conductance of Solids

A Conductivity tester will be provided to each group, who will determine the conductivity of each sample provided. Make sure you rinse and dry the conductivity tester's probe wires between each sample to minimize contamination of the samples use the conductivity tester to test the conductance of each sample.

LAB 10 PART A DISCUSSION.mp4

Part A

This video discussed the conductance of the solids in Part A of the laboratory report

What Happens when Stuff Dissolves?

Tyler DeWitt - We'll look at what happens when you dissolve ionic and covalent compounds in water. Ionic compounds break apart into the ions that make them up, a process called dissociation, while covalent compounds only break into the molecules, not the individual atoms.

conductivity/solubility of solids/solutions

BerkeleyChemDemos: https://youtu.be/4FLFy3mrjD4

This demonstration shows the conductivity of solids and aqueous solutions of the solids.

Part B - Conductance of liquids and solutions.

We will use a simulation to measure the conductivity of several ionic compounds. The video can be use to determine the conductivity of several molecular compounds.

Use the following simulation to measure the conductivity of several acid, base and ionic salt solutions. The directions for using this simulation are in Virtual Experiment 10.

http://web.mst.edu/~gbert/conductivity/cond.html

To measure the conductivity of several liquids and solutions, we will use the MicroLab system and a conductivity probe. The system set up and calibration of the conductivity probe is described in this video.

Set up the MicroLab and Conductivity probe and then calibrate the probe. This is a document showing how to calibrate the probe. http://microlabinfo.com/wp-content/uploads/2013/08/Calibration-Handout.pdf

MicroLab will be used to collect some of the data for this experiment. The directions for using this program is available at

https://drive.google.com/open?id=1msCKCy0Y5CNKjrLCZj8S4w633NE0H7SZXstbaV10RkY

Exp 10Calibration.mp4

This video show how the microlab conductivity probe was calibrated with solutions of KCl.

LAB 10 Part B conductivity of solutions and liquids.mp4

Video of me performing Part B, measuring the conductivity of several solutions. Use this video to see the conductivity of several of the ionic compounds, acids and molecular compounds in the laboratory report. Note the concentration of the ionic compounds and acids are 0.1 M rather than 0.001 M as indicated in the simulation.

We can use standardized solutions to calibrate the conductivity probe and then measure the conductance of each of the solutions.

Electrolytes

Part C - Effects of Concentration on Conductance.

We will prepare serial dilutions of two solutions and test the solution's conductance. Use the above simulation to measure the conductance of acetic acid and NaCl solution at various concentration. We will graph the concentration of the solution versus the conductance.

Concentration of a solution can affect the conductivity. If there are less ions in solution, then generally there will be less conductance in the solution

LAB 10 Part C effect of concentration.mp4

Part C

This video shows the completion of Part C with the dilution and graphing of the data for Acetic acid.

Part D - Testing how chemical reactions affect conductance

We will set up the titration of two different reactions. You need to be able to predict the products of the reaction of these two solutions. Identify whether the products are strong, weak or non electrolytes, soluble or insoluble compounds. The instructor may set up one computer for each of these reactions to allow the student to graph conductivity as a result of time and added substrate. These involve changes occurring to the conductivity of the original sample. Net ionic reactions will help explain the change in conductivity if the products of the reaction are understood to be either strong electrolytes, weak electrolytes or non electrolytes. A graph of the conductance versus the volume of the titrant added will be created.

In a titration, when two separate aqueous ionic compounds are mixed the ions may interact. The ionic compounds in a double replacement reaction switches partners. If these partners result in an ionic compound that remains dissolved, then the products of the mixture are strong electrolytes and the reaction is said to have no apparent reaction. When the product of the double replacement reaction is a precipitate or solid, a weak electrolyte or acid, a non electrolyte or a gaseous substance, the removal of the freely dissociated ions can cause a decrease in the conductivity of the solutions. Sometimes the reaction results in the formation of a strong electrolyte from weak electrolytes.

Exp 10 part C.mp4

Part D

This video presents the reactions and graphs for Part D, use the discussion to answer the questions about the two titrations performed D.

Post Laboratory Problems and Conclusion paragraph

There are no post laboratory problems or conclusion paragraph for this laboratory assignment.

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