Question

2. How many moles of helium are present in a balloon at STP if the volume is 3.7 L? Please show all work!

Answer 1

Using the Ideal Gas Law equation:
`PV=nRT`

• P = pressure (kPa)
• V = volume (L)
• n = moles (mol)
• R = gas constant(
  `(kPaL)/(molK)`)
• T = Temperature (K)

STP also known as Standard Temperature and Pressure is a set of conditions at sea level

At STP:

P = 101.3 kPa

T =
`0^o C` or 273 K

`n=(PV)/(RT)`

`n=(101.3kPa)(3.7L))/((8.31(kPaL)/(molK))(273K))`

`n = 0.16 mol`