7. When studying surface films on a Langmuir balance, a benzene solution of palmitic acid С15Н31СООН with a concentration of 0.4% (mass) was applied to the water surface. By weighing, it was determined that the mass of 100 drops of the solution is 0.33 g. 5 drops of the solution were applied to the surface of the water between two partitions. After evaporation of benzene, an insoluble acid film remained on the surface. When moving the movable partition towards the fixed one, a sharp increase in surface pressure was registered, when the distance between the partitions was 23 cm in length and 14 cm in width. Determine the area occupied by one molecule during the formation of a monolayer on the surface. Calculate the length per CH2 group. The density of palmitic acid in the liquid state and in the form of a film is 0.850 g/cm3.

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