8. Analytical chem question on sapling correct answer will get rated, thanks! A

Question

8. Analytical chem question on sapling

correct answer will get rated, thanks!

A sample containing anthracene dissolved in methane was separated using gas chromatography. Methane was detected at 48.2 seconds (tm) and anthracene was detected at 180.1 seconds (tr). If the manufacturer of the column states that the volume of the mobile phase (Vm) is 7.0 times the volume of the stationary phase (Vs), calculate both the retention factor (k) and the partition coefficient (K) for anthracene in this separation.

k= ? , K = ?

HINT = The retention factor is the ratio of time the solute spends in the stationary phase to the time it spends in the mobile phase. The partition coefficient is an equilibrum constant that describes the ratio of the solute concentration in the stationary and mobile phases. The retention factor is also known as the capacity factor, capacity ratio, or partition ratio. It was previously written as k' instead of k.

Explanation / Answer

we know that

retention factor (k) = ( tr - tm) / tm

given

tr = 180.1

and

tm = 48.2

so

using these values

we get

k = ( 180.1 - 48.2) / 48.2

k = 2.7365

so

the retention facotr (k) = 2.7365

now

also

we know that

partition coefficient (K) = k ( Vm/Vs)

given

Vm/Vs = 7

so

K = 7k

K = 7 x 2.7365

K = 19.15

so

the partition coefficient is 19.15

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