Answer:
3.9 atm
Explanation:
Ideal gas law states:
PV = nRT
where P is absolute pressure,
V is volume,
n is number of moles,
R is universal gas constant,
and T is absolute temperature.
The volume of the tank is constant, so we can say:
V₁ = V₂
Using ideal gas law to write in terms of P, n, R, and T:
n₁ R T₁ / P₁ = n₂ R T₂ / P₂
n₁ T₁ / P₁ = n₂ T₂ / P₂
Initially:
P₁ = 9.8 atm
T₁ = 29.0°C = 302.15 K
n₁ = n
Afterwards:
P₂ = P
T₂ = 83.0°C = 356.15 K
n₂ = n/3
Substituting:
n (302.15 K) / (9.8 atm) = (n/3) (356.15 K) / P
(302.15 K) / (9.8 atm) = (1/3) (356.15 K) / P
P = 3.85 atm
Rounding to 2 significant figures, P = 3.9 atm.
