Mixed gas laws help

Question

How many moles of helium gas would it take to fill a balloon with a volume of 1260.0 cm³ when the temperature is 32°C and the atmosphere pressure is 752 mm Hg?

Answer 1

The best way to solve this is by using the ideal gas law her than the Combined gas Law:

n = PV/RT (752/760 atim)(1.260 liters)/(.0821)(32+273 K))

You can use the fact that there is 22.4 liters/ mole at STP by using CGL to modify the volume:

V_STP = V_TP(273/T in K)(P/760 mmHg) (T is proportional to volume and P is inversely proportional

n = V_STP in liters * 1 mole/22.4 liters