Our data showed that 2 drops and 1 drop both had an average time of 29 seconds.

Question

Our data showed that 2 drops and 1 drop both had an average time of 29 seconds.

We are supposed to explain whether our data is consistent with the rate law for an SN2 reaction with the rate=k[nucleophile][substrate]

We increased the amount of substrate, but the rate did not increase even though it is directly proportional.

How should I explain this in my lab report?

That the amount was negligibly different one/two drops, or that perhaps an error in lab cleanliness accounted for it?

Thanks ahead of time.

Add 1.0mL of 15% sodium iodide in acetone to each of two clean, dry test tubes. Place them in the heat bath for 4 min Locate and have ready the reagent bottle of 1 bromobutane. Remove a test tube and add to it two drops of 1-bromobutane, record the time or start a stopwatch, and mix it on the Vortex mixer set at "7" for 10s. Return it to the heat bath. Periodically remove it from the bath and shake it and look for precipitate or cloudiness. Repeat this with the second test tube using one drop of 1- bromobutane recording the mixing time. Continue to shake and examine both test tubes. Record the time elapsed to the first appearance of precipitate.

Explanation / Answer

You will be able to see the change in rate only if you keep the nucleophile concentration constant and then try changing substrate concentration. On the other hand if you change both of then simalteneously the effect of change could balance each other.

Proper way to do it is : Fix the nucleophile concentration and then change substrate concentration -- see how the rate changes. Suppose when you double the substrate concentration rate also doubles ......this means that this is 1st order with respect to substrate concentration

Next step : keep the substrate concentration constant and try changing nucleophile concentration . See how the rate is changing. Like the previous situation , if doubling the nucleophile concentration doubles the reaction rate then the reaction is 1st order with respect to nucleophile concentration .

Combine the two and you have a second order SN2 reaction .

----------------------------

If you have done exactly the way I have mentioned and still you are getting the same result, then there must be some error.

Related Questions

Navigate

• Browse (All)
• Browse O
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.