Ideal Gas Law Question: Calculating Final Balloon Volume at High Altitude

[blackjack18]

A sealed balloon is filled with 1.00 L of He gas at 23 deg C and 1.00 atm. The balloon rises to a point in the atmosphere where the pressure is 220 torr and the temperature is -31 deg C. What is the final volume of the balloon after it reaches an altitude where the pressure is 220 torr?

If I should use the Ideal Gas Law, Pv= nRT, how do I find the number of moles?

 

[LowlyPion]

A sealed balloon is filled with 1.00 L of He gas at 23 deg C and 1.00 atm. The balloon rises to a point in the atmosphere where the pressure is 220 torr and the temperature is -31 deg C. What is the final volume of the balloon after it reaches an altitude where the pressure is 220 torr?

If I should use the Ideal Gas Law, Pv= nRT, how do I find the number of moles?

You are not asked for the number of moles. (Hint: You don't need it either.)

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