The following data were obtained by gas-liquid chromatography on a 40-cm packed column: Compound tR, min W, min
Air 1.9 —
Methylcyclohexane 10 0.76
Methylcyclohexene 10.9 0.82
Toluene 13.4 1.06

Calculate:
a. an average number of plates from the data.
b. the standard deviation for the average in (a).
c. an average plate height for the column.

a)

For Methylcyclohexane  N₁ = 2770

For Methylcyclohexene N₂ = 2827

For Toluene N₃ = 2557

b) the standard deviation for the average in (a) is 143.31

c)

For Methylcyclohexane; H₁ = 0.01444 cm

For Methylcyclohexene; H₂ = 0.01415 cm

For Toluene; H₃ = 0.01564 cm

Explanation:

Given the data in the question;

Gas-liquid chromatography on a 40-cm packed column:

Compound                   tR, min                           W, min

Air                                   1.9                                    —

Methylcyclohexane      10.0                               0.76

Methylcyclohexene      10.9                               0.82

Toluene                        13.4                                1.06

a)

an average number of plates from the data;

To get the Number of plates N, we use the following expression;

N = 16( tR / W )², we use it for Methylcyclohexane, Methylcyclohexene and Toluene

-

For Methylcyclohexane  N₁ = 16( 10 / 0.76 )² = 16( 173.13 ) = 2770.08 ≈ 2770

-

For Methylcyclohexene N₂ = 16( 10.9 / 0.82 )² = 16( 176.7 ) = 2827.2 ≈ 2827

-

For Toluene N₃ = 16( 13.4 / 1.06 )² = 16( 159.8078 ) = 2556.9 ≈ 2557

b) standard deviation for the average in (a).

First we get the mean;

Mean N" = ( N₁ + N₂ + N₃ ) / 3 = ( 2770 + 2827 + 2557 ) / 3 = 8154 / 3 = 2718

Next we determine the deviation

d₁² = (N₁ - N")² = (2770 - 2718)² = (52)² = 2704

d₂² = (N₂ - N")² = (2827 - 2718)² = (109)² = 11881

d₃² = (N₃ - N")² = (2557 - 2718)² = (-161)² = 25,921

∴ ∑d² = 40506

Standard Deviation S = √( ∑d²  / ( n-1 ) )

Standard Deviation S = √( 40506 / ( 3-1 )

Standard Deviation S = √( 40506 / 2 )

Standard Deviation S = √( 20253 )

Standard Deviation S = 143.31

Therefore, the standard deviation for the average in (a) is 143.31

c)

an average plate height for the column

Given that; Gas-liquid chromatography on a 40-cm packed column, L = 40 cm

-

For Methylcyclohexane; H₁ = L/N₁ = 40 / 2770 = 0.01444 cm

-

For Methylcyclohexene; H₂ = L/N₂ = 40 / 2827  = 0.01415 cm

-

For Toluene; H₃ = L/N₃ = 40 / 2557 = 0.01564 cm

hope this

explanation:

covalent bonds

consist of pairs of electrons shared by two atoms, and bind the atoms to fixed orientation and requre high energies to break them

ionic bonds

when two atoms differ considerably in their electronegativity, then one of the atoms will lose its electron to the other atom. this results in a positively charged ion(cation) and a negatively charged ion (anion)

the answer is a and have a great day