Report: Crystal Violet Kinetics
(Total 80 Points)
On my honor, in preparing this report, I know that I am free to use references and consult with others. However, I cannot copy from other students’ work (including my laboratory partner) or misrepresent my own data.
Name(Print then sign): ______
Lab Day: ______Section: ______TA______
CV Reaction Order (y)
Key Equation: (y = 1 or 2)
Part 1 (using 0.050 M NaOH) / y______/ k’ (give units) ______Part 2 (using 0.10 M NaOH) / y______/ k’ (give units) ______
Hydroxide Reaction Order (x)
Key equation: (x = 1 or 2)
x ______rounded x ______
Show one of the above dilution calculations and the calculation of x.
Rate Constant (k)
Key equation: (use rounded x)
Part 1 / Part 2, after dilution ______/ , after dilution ______
k’ (part 1) ______/ k’ (part 2) ______
k ______/ k______
k average (with units)______
Summary
Final rate law: ______
Rate constant (k) with units:______
1. The formula of crystal violet is . Write a balanced molecular equation, using this formula, for the reaction of crystal violet with NaOH. Then write the balanced net ionic equation.
2. The structure of the crystal violet cation is shown in Figure 1 (Introduction). Which atom in this structure has a 1+ formal charge?
3. Assume that the reaction is first order in crystal violet and that, for a particular NaOH concentration, k’ equals 0.048 . Use Equation 3 to calculate how many minutes it takes for half of the crystal violet to react. This is the half-life of the reaction.
Note everyone is required to hand in six graphs. For the two concentrations you should have a graph for conc vs time, ln(conc) vs time, and 1/conc vs time. You MUST show an example calculation going from intensity reported by the lab works to transmittance, absorbance, and finally to concentration.
4. How many significant figures should the final rate constant have? Be sure to identify the measurement that is used to determine the significant figures.
5. The precision of the instrument is not the accuracy of the instrument, identify two non-measurements (observations) that would give you a reason to even further round your final rate constant.
6. List 5 sources of error in this experiment and discuss what influence each on will have on the rate constant that you find.