Question

Cloth can be waterproofed by coating it with a silicone layer. This is done by exposing the cloth to (CH3)2 SiCl2 vapor. The silicon compound reacts with OH groups on the cloth to form a waterproofing film (density = 1.0 g/cm3) of [(CH3)2SiO]n, where n is a large integer number. The coating is added layer by layer, with each layer of [(CH3)2SiO]n being 0.60 nm thick. Suppose you want to waterproof a piece of cloth that is 5.00 square meters, and you want 290 layers of waterproofing compound on the cloth. What mass of (CH3)2SiCl2 do you need?

Answer 1

for one layer, the amount of silicon compound required = area * thickness * density

for 290 layers, the amount of silicon compound required = 290 * area * thickness * density

density = 1g/cm³ = 1g/(10^-2)³ m³

for 290 layers, the amount of silicon compound required   = 290 *5 m² *(0.6 *10^-9) * 1g/(10^-2)³ m³

                                                                                                         =0.870g