Question

A balloon contains 8.4 L of helium gas at STP. How many moles of helium are in the balloon? 0.38 moles He ,190 moles He ,2.1 moles He ,8.4 moles He

Answer 1

0.38 moles He

Step-by-step explanation:

from the ideal gas law PV= nRT you can calculate the volume of 1 mole at STP (273..1K and 1 atm of pressure) the MOLAR VOLUME IS

22.4 L

In the problem you have 8.4L

8.4 L/22.4 L=0.375 moles

so

0.38 moles He