Once, Paheli visited a tailor shop and brought home some cuttings of fabric to study their properties. She took two pieces and found that one of the pieces were shrinking when it was burnt with a candle. However, the other did not shrink on burning.

Can you help her to find out which of the two was a cotton fabric and which a silk fabric?

AcademicChemistryNCERTClass 6

Cotton fabric is smooth and breezy whereas Silk fabric is smooth and shiny to touch. Cotton fabric does not shrink but silk fabric shrinks on burning due to the presence of protein.

She can perform an activity under supervision to help her understand the difference between the two fibres better.

Activity:

To observe the difference between a cotton and a silk yarn taken from the fabric pieces.

Experiment:

Pull out six to eight yarns from the fabric. Hold one end of the yarn with a tong and bring the other end over the flame of a candle.

Observation and Inference:
  1. If the yarns burn but do not shrink or melt, and give an odour similar to the burning of paper, then it is cotton yarn.
  2. If yarn shrinks away from the flame and burns but does not melt and has the odour of charred meat, then it is silk yarn.
raja
Updated on 10-Oct-2022 13:19:52

Advertisements