# Chem

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If 4.0 grams of hydroven, 6.02 x 10^22 atoms of helium and 4.48 liters of argon, measured at STP are placed in a 2.0 liter flask, at 27 degrees C, what is the final pressure?

Under controlled conditions the velocity of hydrogen molecules was found to be 250 meters/sec, and the velocity of an unknown gas was found to be 88.4 meters/sec. What is the molecular weight of the unknown gas?

• Chem -

convert 4 g hydrogen to moles.
Convert 6.02 x 10^22 atoms He to moles.
Convert 4.48 L Ar to moles.
Add all the moles together and use PV - nRT to solve for pressure.

• Chem -

but how do u convert L to moles?

• Chem -

It is at STP, so use 22.4 L per mole

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