CHEM 120 Week 2 iLab

iLab 2 of 7: Cations and Anions . For this week’s lab, you will conduct the following Model ChemLab experiment: Cations and Anion Reaction. This experiment will demonstrate a double-replacement reaction of ionic compounds. In this experiment, you will mix two ionic compounds. Both compounds are soluble in water. If a reaction occurs between these two compounds, then a precipitate will form because one of the two resultant compounds is not soluble in water. This is evidence that a reaction occurred. The following reaction will occur: lead nitrate + potassium chromate à potassium nitrate + lead chromate The following is the balanced chemical reaction:

Pb(NO3)2 + K2CrO4 –> 2 KNO3 + PbCrO4

iLab 2 of 7: Cations and Anions Deliverables

NOTE – Submit your assignment to the Dropbox, located at the top of this page. For instructions on how to use the Dropbox, read these step-by-step instructions. (See the Syllabus section “Due Dates for Assignments & Exams” for due dates.)

For each lab experiment, you will write a laboratory report. Download the iLab Week 2 Report Template. In your lab report, you should include the information below.

Title Introduction:

The first section of your lab report will be the introduction. In this paragraph(s), you are to provide information to the reader so that he or she can understand the purpose of the experiment.

Purpose:

This is a concise statement about the lab’s objective.

iLab 2 of 7: Cations and Anions  Background:

This is a brief summary of the topic you are investigating. Include any information that would be necessary to understand the stated purpose.

Findings:

State the major results of the lab exercise.

iLab 2 of 7: Cations and Anions  Procedure:

This is the second section of your lab report. This section includes information that the reader would need in order to repeat the experimental procedure. Do not include any observations or results in this section. Some questions that you should ask yourself to complete this section include: What chemicals did I use? What equipment did I use? How much of each chemical did I use? How long did I perform a step within the procedure?

iLab 2 of 7: Cations and Anions  Observations and Results:

This is the third section of your report. In this section, you will communicate what you observed during the experiment. The Results section is typically dominated by calculations, tables, and figures. In your tables, label the axes of any graphs.

iLab 2 of 7: Cations and Anions Discussion:

This is the fourth section of your report. In this section, you will explain, analyze, and interpret what you observed. You will draw conclusions from what you know. This is also where you show the reader that you understand the significance or meaning of the results.

Conclusion:

This is the last section of your report and is separate from the Discussion section. In a few sentences, provide a concluding statement about the results of your laboratory. In a scientific publication, this section summarizes the significant aspects and results and identifies implications for future study.

iLab 2 of 7: Cations and Anions Required Software

Model ChemLab v 2.4

Access the software at https://lab.devry.edu. Steps: All

iLab 2 of 7: Cations and Anions Grading Rubric

Category	Points	Description
Introduction	5	The background material is complete.Does the description set the stage for the reader?
Procedure	5	The lab report follows correct and complete procedures.
Observations and Results	5	Were the results accurate? Were all results included?
Discussion	5	Was an interpretation of the results included?
Conclusion	5	Was a concluding statement included?
Writing Quality	5	The lab report contains correct grammar, spelling, originality, completeness, and so forth.
Total	30

A laboratory report will meet or exceed all of the above requirements.

Lab Steps

STEP 1: Access Model ChemLab Software

Log into the lab software by clicking the Connect to the iLab Here link, provided at the top of this page. Follow the information to log into the lab environment, which can be found in the iLab section under Course Home.

Select Model ChemLab v 2.4. Once the application loads, select the Cation and Anion Lab and click OK.

For an overview of the Model ChemLab software, and navigation within the program, view the following orientation tutorial.

Tutorial

Cell Structure Model ChemLab Tutorial

This tutorial gives an overview of the Model ChemLab software and navigates within the program.

Duration: 01:31 minutes

STEP 2: Conduct Experiment

Step 1: Add 50 ml(s) of potassium chromate 1M solution in a 100ml beaker.

Use the Chemicals selection from the toolbar.

Select All Chemicals from the dropdown menu.

Using the dropdown menu, select 1M Potassium Chromate.

Change the volume to 50 mL. Make sure that on the lower part of the window, you have indicated that the potassium chromate is to be added to a new 100 mL beaker.

Click OK.

Note: A beaker will appear in the workspace. Half of the beaker will appear white; this is the 50 mL of potassium chromate.

Step 2: Add 50 ml of lead (II) nitrate 1M into the same 100 mL beaker.

Using your mouse, left-click on the beaker in the workspace. A dotted line will appear around the beaker. You have selected the beaker.

Use the Chemicals selection from the toolbar.

Select All Chemicals from the dropdown menu.

Using the dropdown menu, select 1M Lead Nitrate.

Change the volume to 50 mL. Make sure that the lower part of the window indicates that the lead nitrate is to be placed in picked 100 mL beaker.

Click OK.

Note: You will see the volume increase to 100 mL. You will also see the solution become dotted, with a line on the bottom of the beaker. This is your indication that a reaction occurred and a precipitate has formed and settled on the bottom of the beaker.

Step 3: Filter the resulting precipitate into a 250 mL Erlenmeyer flask with a Buchner funnel.

Now, you want to set up an Erlenmeyer flask with a Buchner funnel.

From the toolbar, select Equipment. From the dropdown menu, select Erlenmeyer Flask—250 mL.

Using your mouse, right-click on the Erlenmeyer flask and choose Buchner Funnel from the available selections. This adds a Buchner funnel to your Erlenmeyer flask.

On the 100 mL beaker, right-click on Pour/Decant. The flask will turn on its side.

Move the beaker above the Buchner funnel. When you have it positioned correctly, the solution will pour into the funnel. Note: You will now see a white area on the bottom of the flask. This indicates that you have filtered your solution.

Step 4: Record the weight of the resulting precipitate by removing the Buchner funnel and placing the resulting precipitate into a test tube.

Right-click on the flask. Select Buchner Funnel. A window will appear.

The message asks, “An amount of solid was found present in the filter on this piece of equipment. What action would you like to take?”

Select Place Solid into 50mL Test Tube.

Click OK.

Note: A test tube will appear with a small amount of precipitate on the bottom.

To measure the weight of the precipitate, right-click on the test tube, and select Show Weight. The weight of the precipitate will appear below the test tube.

Note: In the Observations and Results section of your lab report, describe the appearance of the precipitate and its weight.

STEP 3: Write Lab Report

Follow the directions above to write your lab report. Use the Lab Report template that is provided above.

In your lab report, include the following information in the Discussion section of your report.

Describe the appearance of the precipitate in your observations and results section.

Include the weight of the filtered precipitate in your observations and results section.

Identify the anion and cation for each ionic compound in your discussion section.

In your Discussion section, discuss the chemistry of the reaction.