35 - Heat and Thermodynamics Questions Answers
A gaseous mixture consists of 16g of helium and 16g of oxygen. the ratio Cp/Cv of the mixture is
(1) 1.59
(2) 1.62
(3) 1.4
(4) 1.54
16 gms He = 4 mole, 16 gms O2= 1/2 mole
so total freedom n = [4(3) + 1/2(5)] / [4 + 1/2] = 3.22222 here 3 and 5 are freedoms for mono and di atomic gases
so γ = 1 + 2/3.2222222 = 1.621
A vessel of volume 0.3 m³ contains helium at 20.0°C. the average kinetic energy per molecule for the gas is
(1) 6.07 * 10^(-21) J
(2) 7.3 * 10³ J
(3) 14.6 * 10³ J
(4) 12.14 * 10^(-21) J
Use the formula 3/2 kT
k is boltzmann constant = 1.38* 10-23
4 moles of an ideal monoatomic gas is mixed with 6 moles of a non reactive diatomic ideal gas. the molar heat capacity of the mixture at constant volume is (assume no vibration) nearly
(1) 27 J mol‾¹K‾¹
(2) 17 J mol‾¹K‾¹
(3) 7 J mol‾¹K‾¹
(4) 37 J mol‾¹K‾¹
at constant volume work done = 0
degree of freedom = 4(3) + 6(5) / 4 + 6 = 12+30/10 = 4.2 so γ = 1 + (2/4.2)
so molar heat capacity = R/(γ-1)
consider an ideal gas contained in a vessel. if the intermolecular interaction suddenly beings to act, which of the following will happen?
(1) the pressure decreases
(2) the pressure increases
(3) the pressure remain unchanged
(4) the gas collapses
if the intermolecular interaction suddenly beings to act, then the pressure increases because due to intermolecular interaction gase will work as real gas
A 20 cm long test tube (cylindrical) is inverted & pushed vertically down into the water . when the closed end is at water surface, how high has the water risen inside the tube? [p atm =10^5 N/m²]
Let the height of water in the tube is x cm. then according to PV = constant, calculate the pressure by (20-x) cm. column
then P0 + pressure by 20 cm water = pressure by (20-x) cm. column + pressure by x cm water column