Question

Consider the expansion of a helium balloon at 20°C. If the balloon is initially inflated to a volume of 3.0 L and then expands to a volume of 44 L under constant pressure, what is the new temperature of the air inside the balloon in "C? Numeric Answer:

Answer 1

Given

Pressure & mass are constant.

Initial volume of air in ballon ( V ₁ ) = 3.0 L

Initial temperature of air in ballon ( T ₁ ) = 20 + 273 = 293 K

New volume of air in ballon ( V ₂ ) =4.4 L

New temperature of air in ballon ( T ₂ ) =?

We can apply here Charles law.

From Charles law, We can write relation V ₁ / T ₁ = V ₂ / T ₂ ------------------>(1)

$\therefore$ 3.0 L / 293 K = 4.4 L /  T ₂

$\therefore$  T ₂ = 4.4 L ( 293 K / 3.0 L ) = 429.7 K

$\therefore$ T ₂ = 429.7 - 273 = 156.7 ⁰ C

ANSWER : The new temperature of air inside the ballon is 156.7 ⁰ C