Answer to Question #222198 in Chemistry for caleb villarreal

Question

 If 0.42 mole of helium occupies 9.9 L, how many moles must be added to inflate the balloon to 17.0 L? (round to two sig figs)

Answer 1

n₁ = 0.42 mol

V₁ = 9.9 L

n₂ = unknown

V₂ = 17.0 L

Solution:

PV = nRT

V/n = RT/P

RT/P = const

Therefore,

V₁/n₁ = V₂/n₂

n₂ = n₁V₂ / V₁

n₂ = (0.42 mol × 17.0 L) / (9.9 L) = 0.72 mol

n₂ = 0.72 mol

moles added:

0.72 mol - 0.42 mol = 0.30 mol

Answer: 0.30 mol of helium must be added to inflate the balloon to 15.6 L.