Chem Help!!
posted by Lisa on .
The volume of a red blood cell is about
90.0*10^12cm^3
Assuming that the red blood cells are spherical, what is the diameter of a red blood cell in millimeters?

volume of a sphere=90.0 x 10^12cm^3 =4/3πr^3
Solve for r
r={[(90.0 x 10^12cm^3)*(3/4)]/π}^1/3
The units that you will get will be in cm, so multiply your answer by 10^1 to get mm. 
V sphere = (4/3)*pi*r^3
90E12 = (4/3)*pi*r^3
r^3 = ?
r = ?
diameter = 2*r = ? in cm
Convert to mm. 
Devron, I believe you multiply cm x 10 to convert to mm.

Typo, 10^1, which is 10.
I apologize. Thank you for catching that for me, and multiply r by 2 afterwards to get the diameter. 
When I converted with Devron method I got
27.8*10^6mm
When I did it Bob's way I got 27.8*10^5
is this correct? 
After I multiplied by 2 I got a final answer of 0.000556mm

volume of a sphere=90.0 x 10^12cm^3 =4/3πr^3
Solve for r
r={[(90.0 x 10^12cm^3)*(3/4)]/π}^1/3
The units that you will get will be in cm, so multiply your answer by 10 to get mm, and multiply by 2 afterwards to get the diameter.
The methods that I and Dr. Bob222 both showed you are the same. I calculated 5.56 x103 mm, but double check my calculations. 
ok cool thanks for your help