Chemistry 103/113 Laboratory

 

 

This Week

Answer Keys

Gen Chem Lab

Periodic Table

 

 

 

·       Week 1 of Expt 2:  What Anions Are In Your Drinking Water?

·       Lab Drawer Check In

·       Complete Study Assignment D in the manual; due Friday by 4 p.m.

 

Next Week

·       Week 2 of Expt2:  What Anions Are In Your Drinking Water?

·       Complete/Check Study Assignment C

·       Quiz 1:  Study Assignments A, B

o      ~15 minutes, after lab lecture/before lab

o      questions similar to ones on the worksheets in the study assignments

o      see a sample quiz

 

Notes for Today

Lab Drawer Check In (after completing today’s expt)

·       Locate assigned drawer (see check in sheet)

·       Check drawer contents vs. list (clean/replace as needed)

·       Sign sheet/return to TA

·       Lock drawer and take the key

 

The Ion Chromatograph

 

Ion Chromatography Vocabulary

·       Sample = drinking water samples (unknown anion concentrations)

·       Standard = solution whose anion concentration is known

·       Stock solution = concentrated solution from which standards are prepared

·       Stationary phase = ion exchange resin on which anions are separated

·       Mobile phase (eluent) = solution that flows through the stationary phase in the separation column

·       Conductivity = a way of detecting the separated anions

 

What Happens in Ion Chromatography?

  • Sample (containing anion mixture – blue, pink, yellow) is injected into separation column

         

  • Anions are separated in the column
    • ‘Blue’ anions are very attracted to ion exchange resin, ‘yellow’ anions are least attracted
    • All anions are swept through the column by eluent

  • Separated anions are sensed by the detector
    • Each anion generates a conductivity ‘signal’
    • More anions = bigger conductivity signal

      

The Ion Chromatogram

  • Plot of conductivity detector signal vs. time
  • Peak time gives identity of anion
  • Peak area gives concentration of anion

            

 

Tasks for Today

  • Prepare drinking water samples (whole class activity)
  • Visit the IC lab (small groups)
  • Taste tests (individual activity)
    • Test 10+ samples
  • Prepare anion standard for IC (individual activity)
    • Why?  What information comes from the standards?
    • TA will assign you an anion/concentration.
    • Dilute stock solution using burets
    • Safety goggles required during standard solution preparation

 

Week 1 Report

·       Purpose, Procedure due today at end of lab

·       See Writing Your Report for remaining requirements

o      Justify the precision you report in calculations

·       How many significant figures are in measured, given numbers?

·       How do s.f. rules (see SA-B rules) affect calculation results?

·       Due tomorrow, 9 p.m., TA folder outside 184