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## Homework Statement

Helium is used to fill a balloon of diameter 44 cm at 22 degrees C and 0.9 atm.

The mass of a helium atom is 4.0026 u, the conversion factor from u to kg is 1.66 x 10^-27 kg/u, the conversion factor from atm to Pa is 1.013 X 10^5 Pa/atm, the universal gas constant is 8.31451 J/K mol, the Boltzmann's constant is 1.38066 x 10^-23 J/K.

What is the average speed (ie, the root mean square speed) of each Helium atom? Answer in units of m/s.

## Homework Equations

Vrms = sqrt(3RT/M)

## The Attempt at a Solution

I think my problem is with finding the mass. I did this:

4.0026 x 1.66 x 10^-27 = 6.644316 x 10^-27

Then:

T = 22C = 295K

R = 8.31451

Sqrt( (3 x 8.31451 x 295)/6.644316 x 10^-27)

I got:

1.0523612 x 10^15

That is wrong. Any help on where I messed up? Thanks.