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0.27 g of a long chain fatty acid was dissolved in 100 cm3 of hexane. 10 mL of this solution was added dropwise to the surface of water in a round watch glass. Hexane evaporates and monolayer is formed. The distance from edge to centre of the watch glass is 10 cm. What is the height of the monolayer?

[Density of fatty acid = 0.9 g cm−3; = 3]

(a)

10−8

(b)

10−4

(c)

10−2

(d)

10−6



Question ID - 52489 | SaraNextGen Top Answer

0.27 g of a long chain fatty acid was dissolved in 100 cm3 of hexane. 10 mL of this solution was added dropwise to the surface of water in a round watch glass. Hexane evaporates and monolayer is formed. The distance from edge to centre of the watch glass is 10 cm. What is the height of the monolayer?

[Density of fatty acid = 0.9 g cm−3; = 3]

(a)

10−8

(b)

10−4

(c)

10−2

(d)

10−6

1 Answer
127 votes
Answer Key / Explanation : (d) -

0.27 gm in 100 ml of hexane

∴ in 10 ml of aqueous solution only 0.027 gm acid is present

Volume of 0.027g acid = ml

r2h =  (given r = 10 cm,  = 3)

∴ h = 10−4cm

      = 10−6m

127 votes


127