Consider a classroom that is roughly 8.21 m × 10 m × 3 m. Initially T = 290 K and P = 1 atm. There are 50 people in the class, each losing energy to the room at the average rate of 166 W. Assume that

Question

Consider a classroom that is roughly 8.21 m × 10 m × 3 m. Initially T = 290 K and P = 1 atm. There are 50 people in the class, each losing energy to the room at the average rate of 166 W. Assume that the walls, ceiling, floor, and furniture are perfectly insulated and do not absorb any heat. Also assume that all the doors and windows are tightly closed to prevent any exchange of air from surrounding. How long (in sec) will the physical chemistry examination last if the professor (Mr Neeraj Kumar) has foolishly agreed to dismiss the class when the air temperature in the room reaches body temperature, 310 K? For air, C_P,m = 7R/2. (R = 0.0821 L-atm/K-mol = 8.3 J/K-mol)

Answer:

517.00

Solution:

V = 246.3 m³ = 246300 L fixed. n = (PV)/(RT) = 246300/(0.0821×290) = 10345 mol. Constant volume: C_V = C_P - R = 5R/2. Q = nC_VΔ T = 10345×2.5×8.3×20 = 4.293×10⁶ J. Power = 50×166 = 8300 W. t = 4.293×10⁶/8300 = 517 s. Ans = 0517.

TestHub · Accepted Answer

V = 246.3 m 3 = 246300 L fixed. n = (PV)/(RT) = 246300/(0.0821×290) = 10345 mol. Constant volume: C V = C P - R = 5R/2. Q = nC V Δ T = 10345×2.5×8.3×20 = 4.293×10 6 J. Power = 50×166 = 8300 W. t = 4.293×10 6 /8300 = 517 s. Ans = 0517.

Chemistry - Thermodynamics - I Question with Solution | TestHub

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