A cylinder of fixed capacity (ot 44.8 L) contains 2 moles of helium gas at STP. What is the amount of heat needed to raise the temperature of the gas in the cylinder by 20° C ? (Use R = 8.31 Jmol-1K-1)

Question

A cylinder of fixed capacity (ot 44.8 L) contains 2 moles of helium gas at STP. What is the amount of heat needed to raise the temperature of the gas in the cylinder by 20° C ? (Use R = 8.31 Jmol-1K-1) (A) 996 J (B) 831 J (C) 498 J (D) 374 J

Tardigrade Admin · Accepted Answer

Since, the volume of cylinder is fixed and helium is a monoatomic gas. The internal energy =μ CvΔ T U=(1/2)f μ RΔ T [∴ Cv=(1/2)f R] U=(1/2)×3×8.32×20. = 498.6 J

Q. A cylinder of fixed capacity (ot 44.8 L) contains 2 moles of helium gas at STP. What is the amount of heat needed to raise the temperature of the gas in the cylinder by $2 0^{\circ} C$ ? (Use R = 8.31 Jmol $^{- 1} K^{- 1})$

996 J

831 J

498 J

374 J

Since, the volume of cylinder is fixed and helium is a monoatomic gas.
The internal energy $= μ C_{v} Δ T$
$U = \frac{1}{2} f μ R Δ T$ $[∴ C_{v} = \frac{1}{2} f R]$
$U = \frac{1}{2} \times 3 \times 8.32 \times 20.$
= 498.6 J

Q. A cylinder of fixed capacity (ot 44.8 L) contains 2 moles of helium gas at STP. What is the amount of heat needed to raise the temperature of the gas in the cylinder by 20∘C ? (Use R = 8.31 Jmol−1K−1)