In a paper chromatography experiment, a mixture of plant pigments was resolved using an or… — JAMB UTME

In a paper chromatography experiment, a mixture of plant pigments was resolved using an organic solvent mixture. The solvent front travelled a total distance of $15.0\text{ cm}$ from the baseline. Spot $A$ was found to have a retardation factor ( $R_f$ ) value of $0.60$ . If spot $B$ migrated $3.0\text{ cm}$ further than spot $A$ along the chromatogram, what is the $R_f$ value of spot $B$ ?

A
0.20
B
0.40
0.80Cevap
D
1.25

Cevap

0.80

The retardation factor (

R_f

) is defined as

R_f = \frac{\text{distance moved by solute}}{\text{distance moved by solvent front}}

. First, calculate the distance moved by spot

A

0.60 \times 15.0\text{ cm} = 9.0\text{ cm}

. Spot

B

moved

3.0\text{ cm}

further, so its total distance from the baseline is

9.0\text{ cm} + 3.0\text{ cm} = 12.0\text{ cm}

. Thus,

R_f(B) = \frac{12.0\text{ cm}}{15.0\text{ cm}} = 0.80

Adım Adım Çözüm

Calculate the distance travelled by spot A from the baseline.

\text{Distance}_A = R_f(A) \times \text{Solvent Front Distance} = 0.60 \times 15.0\text{ cm} = 9.0\text{ cm}

The

R_f

value is defined as the ratio of solute distance to solvent front distance.

Determine the total distance travelled by spot B from the baseline.

\text{Distance}_B = \text{Distance}_A + 3.0\text{ cm} = 9.0\text{ cm} + 3.0\text{ cm} = 12.0\text{ cm}

Spot B migrated

3.0\text{ cm}

further than spot A along the paper.

Calculate the

R_f

value of spot B.

R_f(B) = \frac{\text{Distance}_B}{\text{Solvent Front Distance}} = \frac{12.0\text{ cm}}{15.0\text{ cm}} = 0.80

Dividing the distance moved by spot B by the total solvent front distance yields its

R_f

value.

Anahtar Kavram

Calculation of retardation factor (

R_f

) in paper chromatography.

Soru

Cevap

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