objective
The objective of this lab is to identify cotton using its physical and chemical properties.
Materials
- Cotton sample
- Microscope
- Beaker
- Water
- Hydrochloric acid
- Sodium hydroxide
- Phenolphthalein
- Acetone
- Petri dish
- Glass slides
- Cover slips
- Forceps
Procedures
- Visual examination: a) Examine the cotton sample with the naked eye and note its color, texture, and other physical characteristics.
b) Under a microscope, examine the cotton fibers and note the size, shape, and color of the fibers.
- Chemical tests: a) Take a small piece of cotton and put it into a beaker of water. Gently stir the water and cotton with a glass rod. Note the behavior of cotton in water. Cotton is known to be hydrophilic, so it should absorb water.
b) Take another small piece of cotton and put it into a beaker of hydrochloric acid. Observe the reaction of the cotton with the acid. Cotton contains cellulose, and the acid should break down the cellulose, causing the cotton to dissolve.
c) Take another small piece of cotton and put it into a beaker of sodium hydroxide solution. Add a few drops of phenolphthalein solution to the beaker. Note the reaction of the cotton with the sodium hydroxide. Cotton should turn pink in the presence of sodium hydroxide and phenolphthalein.
d) Take a small piece of cotton and place it on a Petri dish. Add a few drops of acetone to the cotton. Observe the reaction of the cotton with acetone. Cotton is known to be insoluble in acetone, so it should not dissolve or change significantly in the presence of acetone.
- Microscopic examination: a) Take a small amount of cotton fibers and place them on a glass slide.
b) Cover the fibers with a cover slip and examine under a microscope.
c) Note the size, shape, and structure of the fibers.
d) Note the presence of any contaminants or other materials in the cotton fibers.
Conclusion: Based on the visual, physical, and chemical properties observed during the experiment, it can be concluded whether or not the sample is cotton. If the sample exhibits all of the properties of cotton, including its characteristic physical appearance, hydrophilic nature, and reaction with chemicals such as sodium hydroxide and hydrochloric acid, then it can be identified as cotton. If the sample does not exhibit these properties, then it is likely not cotton.