In an experiment Kinetics and the Hydration of Chickpeas the following data was

Question

In an experiment Kinetics and the Hydration of Chickpeas the following data was collected

1. Indicate the objective of the experiment.

2. Why was the wavelength of 667 nm used to record the disappearance of methylene blue?

3. If rate constant, (k) for this reaction is 0.00614/s, how long would it take for 99% of methylene blue to be consumed? HINT: use the integrated rate law.

4. For the rate order that you determined from your data, what would you expect to happen to the reactions rate, if you doubled the concentration of the methylene blue? Justify your answer.

Explanation / Answer

1 ) dehydration of chickpeas

2 ) .... Methylene blue is a potent cationic dye with maximum absorption of light around 670 nm.

3 ) from integrated rate law

                     A =A0 * e^-kt

So A/A0 = e^-kt

Here A/A0 =   99/100 (given)   = 0.99 , k = 0.00614/s

So put values 0.99 = e^-0.00614t Take natural log of both sides

ln 0.99   =ln e^-0.00614t

-0.01005 = -0.00614t

(because lne^x = x)

so t = 0.01005/0.00614 =1.636 s

4) from integrated rate law

                     A =A0 * e^-kt

So A/A0 = e^-kt

Here A/A0 = 2* 99/100 (given)   = 0.99 , k = 0.00614/s

So put values 2* 0.99 = e^-0.00614t Take natural log of both sides

ln 2* 0.99   =ln e^-0.00614t

0.6830   = -0.00614 t

So t = 0.6830/0.00614 = 11.23 s

-0.01005 = -0.00614t

(because lne^x = x)

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