Calculating the Rate of Oxygen Escape through a Hole in a Balloon

[Deadsion]

Homework Statement

Suppose we make a circular hole 4 millimeter in diameter in a balloon. Calculate the initial rate at which oxygen escapes through the hole (at 0° C), in number of helium atoms leaving the balloon per second.

Homework Equations

# of molecules/second =(1/4) (Number of molecules/Volume)A(average velocity)

The Attempt at a Solution

Number of molecules - 6.02e23
Volume = .0224 m^3
A=pi*r^2=pi*(.002)^2=1.2566e-5
v=sqrt(3kT/m)=sqrt((3*1.38e-23*273.15)/(16/6.02e23))=425.479

(1/4)(N/V)Av=3.59e22 atoms/s

I did this, but it was wrong, any ideas?

 

[evendim]

i don't expect anyone to see this post but anyway the average velocity v=sqrt(3kT/m) in the equations is wrong..its <v>=sqrt(8kT/pi*m)..