January 24, 2017

Homework Help: Chemistry

Posted by Amy on Monday, November 12, 2012 at 7:55pm.

Chemical Kinetics Lab - Ascorbic Acid Reduction of Iron (III)

The object of this experiment was to determine a rate law and a rate constant. The reaction that was studied was:

2 Fe(CN)6 ^-3 + C6H8O6 = 2 Fe(CN)6 ^-4 + C6H8O6 + 2H ^+

Summary of obtained values:

m = 1
n = 1
k = .632 (rounded to 1)

I'm having trouble with the discussion questions.

The answers to 1 and 2 are supposed to be almost identical.

1.) The normal use of a transfer pipette leaves a small amount of solution in the tip. When pipetting ferricyanide solution in this experiment, this solution was forcibly expelled. Why does this make absolutely no difference (as long as it is done consistently between runs) in the determination of m and n, and a very small one (almost certainly less than the uncertainty) in the value of k?

2.) You made an attempt to determine the best estimate of zero time, i.e., the actual time of mixing. Instead, you simply started taking transmittance readings as soon as possible, effectively calling your first reading zero time. Why is knowing zero time unimportant - at least the way the experiment turned out?

3.) Show that for an isolated second-order reaction, a plot of 1/A vs t is linear, with slope of k'/ab

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