Astudent researcher performed a chromatographic separation of caffeine and aspartame. the retention time for caffeine, t c , was found to be 216.7 s with a baseline peak width, w c , of 13.6 s. the retention time for aspartame, t a , was 267.1 s with a baseline peak width, w a , of 18.9 s. the retention time for the unretained solvent methanol was 45.2 s.

calculate the average plate height, h , in micrometers for this separation, given that it was performed on a 24.1 cm long column.
h = μ m

calculate the resolution, r , for this separation using the widths of the peaks.
r =

calculate the resolution if the number of theoretical plates were to increase by a factor of 1.5 .
r 1.5 n =

Average plate height: 67,4μm

Resolution: 3,10

Resolutin with increase N by a factor of 1,5: 3,80

Explanation:

Average plate height is the average between plate height of aspartame and caffeine.

Plate height is:

For aspartame:

H = 75,4 μm

For caffeine:

H = 59,33 μm

Average plate height is:

(59,3μm + 75.4μm)/2= 67,4μm

The resolution formula is:

Replacing:

R = 3,10

As resolution is proportional to the square root of the number of theoretical plates, the increasing of 1,5 in the number of theoretical plates increases the resolution by a factor of √1,5 ≈ 1,22

That means resolution would be:

R 1,5N = 3,10×√1,5= 3,80

I hope it helps!

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.