A typical dust grain has a radius of 10-7 m and a mass of 10-14 g. How many dust particles are there in a molecular cloud containing 1000*Masssun of dusty gas if 1% of the cloud's mass is in the form of dust grains?
The Attempt at a Solution
1000*Msun = Mcloud * 0.01
Masscloud = 100,000*Msun = 2 * 1038 g.
Then do I just do:
(2 * 1038 g) / (10-14 g) = 2 * 1051 dust particles.
Is that correct?
Then, it asks to find the total surface area these (spherical) grains would take up if side by side. Do I just find S.A. = 4*pi*r2 = 4*pi*(10-7 m)2 = 1.2566*10-11 m2. So:
1.2566*10-11 m2 * (2 * 1051 particles) = 2.5 * 1040 m2 for the surface area. Is that how I'm supposed to do it?