Announcements 9/9/11. Prayer Lab 1 due tomorrow Lab 2 starts tomorrow. Worked problems:. How much mass does the air in this room have? (MM 0.029 kg/mol ) According to the ideal gas law, what is the density of air at 1 atm, for 300 K? For arbitrary T?
Some answers: 1.175 kg/m3; 378K (221F)
Demo: heavy vs light molecules
(*) let’s assume the temperature is “high”.
Relative to what, we’ll discuss in a minute.
Thermal energy (measured by kBT) must be comparable to the quantum energy levels, or some degrees of freedom get “frozen out”
From section 21.4: diatomic hydrogen
Y-axis: heat added, divided by temperature change (per mole)
Answer: 2.45 Pa
Answer: 2mvx/(L2 tbetween hits) = mvx2/L3
Answer: P = Nmvx2/V
P = N m ⅓ v2 / V