Lab 1: Kinetic Rate Law of CV+OH- Lab 1: Kinetic Rate Law of CV+OH-

• Turn in your prelab• OPEN Last Week’s Spreadsheet(s)• Today: Study the Kinetic Rate Law of Reaction: 

Crystal Violet (C25H30N3Cl) (aq) + NaOH (aq) C25H31ON3 (aq) + NaCl Deep purple color clear and colorless 

• Rate law = k [OH-]x [CV]y

• We can study the rate of this reaction by:• Collecting time and % transmission data• Calculating absorption, [CV], ln[CV], and 1/[CV]• Determining x, y, and k from our data

Lab 1: Kinetic Rate Law of CV+OH- Lab 1: Kinetic Rate Law of CV+OH-

• Step One: Calibrate the Instrument (SP-20)• Set the proper λ (590 nm) for Crystal Violet • Use a SINGLE clean cuvet (not a test tube) – hand out cuvets

• Keep outside clean with kimwipes• Line up the line on cuvet with line in sample holder

• Set 0% Transmission – closed drawer, no cuvet (left knob)• Set 100% Transmission – cuvet filled with DI water (right knob)

• Step Two: Data Collection – use spreadsheet from last week• Set Column A to collect data for 35 minutes• Column B will be %T from SP-20• Perform Two trials:

• CV + 0.05 M NaOH ,

• CV + 0.1 M NaOH .

• Save both runs with different file names

Lab 1: Kinetic Rate Law of CV+OH- Lab 1: Kinetic Rate Law of CV+OH-

• Step Three: Experiment NOTES- Crystal Violet

Use gloves to prevent stainingMake note of concentration on bottleDispense 9.00 mL EXACTLY into clean, dry 50 mL

beaker- NaOH

Dispense EXACTLY 1.00 mL into the beaker with CVMake note of concentration on bottle

- CuvetsWipe down with KimwipeFill ¾ fullLine up the line on cuvet with line on doorPLACE BACK IN RACK – DO NOT PUT IN

LOCKER- Begin experiment as soon as possible after mixing- Collect Data for up to 35 minutes (when %T plateaus around 80-90)- Perform 2 Trials:

Trial 1 – use 9.00 mL of CV (from buret) and 1.00 mL of 0.050M NaOH (Vol. pipet)Trial 2 – use 9.00 mL of CV (from buret) and 1.00 mL of 0.10M NaOH (Vol. pipet)

Waste in Container in Fume Hood

CalculationsCalculations

•Determine y

•Graph ln[CV] vs. t (with equation and R2 value) if linear, y = 1

•plot 1/[CV] vs t (with equation and R2 value) if linear, y = 2

•Determine x (must be 1 or 2)

•Since , set up equation and solve for x

•Use M1V1 = M2V2 to determine diluted [OH-]

•Determine k for trials 1 and 2: (should be the same)

  or

yx CVOHkRate ][][

xOHkk ][' xOH

kk

][

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oo CVOH ][][

x

x

ionafterdilutpartOHk

ionafterdilutpartOHk

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1'

2 '

Lab ReportLab Report Title Page

Purpose

Results

EXCEL spreadsheet tables - look for column headers and units!!

Four graphs– Trial 1, 1st and 2nd orderTrial 2, 1st and 2nd ordereach LANDSCAPED on its own full page

Experimental Data Sheet (calculations for y , x , and k) – SHOW CALCS

Significant Figures and Units Conclusion (to include errors and future improvements, no post-lab ????’s)

Individual Checked-Pre-labs

Lab Report (and GCF) due at beginning of next Lab Period. Lab Report (and GCF) due at beginning of next Lab Period.