Question

#5 and 6

Given a solution of 5.0% by volume oleic acid in alcohol. Two drops (100 drops/cm^3) are placed on a water surface and a continuous, circular film a formed 16.0 cm in diameter after all the alcohol has evaporated and the oil is distributed evenly on the surface. What would be the thickness of the layer of pure oil? Suppose you have a box 3.0 cm by 4 5 cm by 6.0 cm filled with lump sugar. If you dumped the lumps of sugar from the box and arranged them in one rectangular layer, the area would be 54.0 cm^2. What would be the thickness of one lump of sugar? If you assume that the lumps of sugar are cubic, how many lumps of sugar were in the box?

Answer 1

First, let us calculate the volume of oleic acid you have added, 2 drops that is 100 drops to a cm^3, so that each drop is 2 * 0.01 = 0.02 cm^3 in volume. Given a solution of 5.0% by volume oleic acid in alcohol, Therefore, 0.05 * 0.02 = 0.001 cm^3 of oleic acid Now, find out the area of the film formed on the water, Given diameter, d = 16cm radius, r = d/2 = 16/2 = 8cm Area of the circular path = Pi.r^2 = 3.14 * 8^2 = 200/96 cm^2 Now, let us assume that the film as a cylinder, so the volume of the cylinder = 0.001cm^3 and area - 201 cm^2 volume of the cylinder = area * height Here we know, volume and area, substitute on the above equation, 0.001 cm^3 = 201 cm^2 * height Height = 0.001/201 h = (1 * 10^-5)/201 = 4.97 * 10^-6 cm Therefore the thickness of the film is = height of the film = 4.97 * 10^-6cm

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