In a paper chromatography experiment, the solvent front moves 12 cm from the base line. A blue dye spot travels 8 cm from the base line. What is the Rf value of the blue dye?
Answer
0.67
The correct answer is 0.67 — Compute Rf = 8 ÷ 12 = 0.666…, which is 0.67 when rounded to two decimal places.
Step-by-step solution
- Recall Rf = distance travelled by solute / distance travelled by solvent front.
- Distance travelled by the blue dye = 8 cm.
- Distance travelled by the solvent front = 12 cm.
- Compute Rf = 8 ÷ 12 = 0.666…, which is 0.67 when rounded to two decimal places.
Common mistake: Using the wrong distance in the numerator or denominator
Concept tested: Paper chromatography
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