CH141 Laboratory

 

Name

CH141 Lab Section

Date

Partners

 

Report for Experiment 4 – Electrical Conductivity of Aqueous Solutions

 

Use complete sentences, use the proper number of digits and/or significant figures, and include units. Erase all the words in italics and type your answers/information into this template (your text/answers shouldn’t be in italics).

 

Introduction: 2-sentence maximum; state the scientific purpose of the experiment. Describe the method you will use, in a general sense.

 

Procedure : Give a brief description of the experimental procedure (a few sentences is sufficient, you do not need to write a full procedure). Reference the experiment handout on the CH141 website. List any changes from the written procedure on the handout (if any).

 

Results : Your results for Experiment 4 are the Excel data table and plot that you produced during the laboratory period (all five titrations). These can be added as attachments to your report. Make sure they are properly labeled (table/figure) with a description. No other information is necessary in the results section for this report.

 

Discussion : Please erase the bullets from the list below when you erase the italicized words. When citing results, r efer to each Table/Figure with an explicit reference as necessary (e.g. see Table 1) in the relevant part of this section.

 

In paragraph form, provide a short discussion of the following topics. Make sure your Disussion sect ion does not exceed one typed page (no smaller than 12-point font).

 

         For each of the two titrations that you carried out, identify the starting solution and the titrant (separately) as being strong or weak electrolytes.

         Explain why the conductivity of the solutions during your titrations never reached zero (this explanation need only be stated once).

 

Choose three titrations to analyze as shown below. Write one paragraph for each titration you are analyzing:

 

NaOH/HCl, NaC 2 H 3 O 2 /HCl, and HC 2 H 3 O 2 /NaOH

– or –

NaOH/HCl, NH 3 /HCl, and NH 4 Cl/NaOH

 

 

 

In the paragraph for each titration, explain the shape of the plotted titration graph and in your explanation include a discussion of:

         Before titrant was added, where is the starting conductivity and why ?

         Does the conductivity increase or decrease upon initial addition of titrant?

         Chemically, why is the slope increasing or decreasing?

         On the graph there is an inflection point, at what point does that occur?

         Chemically, what has caused the observed change at this inflection point?

         Does the conductivity increase or decrease after the inflection point?

         Chemically, why is the slope increasing or decreasing past the inflection point?

 

Attachments:

 

Your Excel data table and plot of all 5 titrations

Your completed Supplemental Report Sheet (2-sided)