In an experiment to estimate the size of a molecule of oleic acid 1 mL of oleic acid is dissolved in 19 mL of alcohol. Then 1 mL of this solution is diluted to 20 mL by adding alcohol. Now 1 drop of this diluted solution is placed on water in a shallow trough. The solution spreads over the surface of water forming one molecule thick layer. Now, lycopodium powder is sprinkled evenly over the film and its diameter is measured. Knowing the volume of the drop and area of the film we can calculate the thickness of the film which will give us the size of oleic acid molecule. Read the passage carefully and answer the following questions: (a) Why do we dissolve oleic acid in alcohol?(b) What is the role of lycopodium powder?(c) What would be the volume of oleic acid in each mL of solution prepared?(d) How will you calculate the volume of n drops of this solution of oleic acid?(e) What will be the volume of oleic acid in one drop of this solution?
Answers
Answer:
Your answer is:
Explanation:
(a) Since Oleic acid does not dissolve in water, hence it is dissolved in alcohol.
(b)Lycopodium powder spreads on the entire surface of water when it is sprinkled evenly. When a drop of prepared solution of oleic acid and alcohol is dropped on water, oleic acid does not dissolve in water. Instead it spreads on the water surface pushing the lycopodium powder away to clear a circular area where the drop falls. We can thus be able to measure the area over which oleic acid spreads.
(c)Since 20 mL (1 mL oleic acid + 19 mL alcohol) contains 1 mL of oleic acid, oleic acid in each mL of the solution =1/20 mL. Further, as this 1 mL is diluted to 20 mL by adding alcohol. In each mL of solution prepared, volume of oleic acid = 1/20 mL x 1/20 = 1/400 mL
(d) Volume of n drops of this solution of oleic acid can be calculated by means of a burette (used to make solution in the form of countable drops) and measuring cylinder and measuring the number of drops.
(e) As 1 mL of solution contains n number of drops, then the volume of oleic acid in one drop will be = 1/(400)n mL
Explanation:
a) because oleic acid is soluble in alcohol
b) to obtain diameter of oleic acid
c)1/10ml
d) diameter of molecule=nv/400cm^3
e)1/400ml