Lecture 24 Act 3 Not being a great athlete, and having lots of money to spend, Gill Bates decides to keep the lake in his back yard at the exact temperature which will maximize the buoyant force on him when he swims. Which of the following would be the best choice? (a)0C(b)4C(c)32(d)100(e)212C Physics 121: Lecture 24, Pg 11
Physics 121: Lecture 24, Pg 11 Lecture 24, Act 3 Not being a great athlete, and having lots of money to spend, Gill Bates decides to keep the lake in his back yard at the exact temperature which will maximize the buoyant force on him when he swims. Which of the following would be the best choice? (a) 0 oC (b) 4 oC (c) 32 oC (d) 100 oC (e) 212 oC
Ideal gas: Macroscopic description Consider a gas in a container of volume V, at pressure P, and at temperature T E quation of state Links these quantities Generally very complicated: but not for ideal gas Equation of state for an ideal gas Collection of atoms/molecules moving randomly No long-range forces Their size(volume) is negligible PVEnRT R is called the universal gas constant n si units. R=8.315/ mol K n= m/m: number of moles Physics 121: Lecture 24, Pg 12
Physics 121: Lecture 24, Pg 12 Ideal gas: Macroscopic description Consider a gas in a container of volume V, at pressure P, and at temperature T Equation of state Links these quantities Generally very complicated: but not for ideal gas PV = nRT R is called the universal gas constant In SI units, R =8.315 J / mol·K n = m/M : number of moles Equation of state for an ideal gas Collection of atoms/molecules moving randomly No long-range forces Their size (volume) is negligible
Boltzmann's constant Number of moles: n= m/M mEmass M=mass of one mole One mole contains NA=6.022X 1023 particles Avogadro's number number of carbon atoms in 12 g of carbon In terms of the total number of particles w PV=nRT=(NNA)RT PV=NkT RNA=1.38X1023JK kp is called the boltzmanns constant P V, and T are the thermodynamics variables Physics 121: Lecture 24, Pg 13
Physics 121: Lecture 24, Pg 13 Boltzmann’s constant In terms of the total number of particles N P, V, and T are the thermodynamics variables PV = nRT = (N/NA ) RT kB is called the Boltzmann’s constant kB = R/NA = 1.38 X 10-23 J/K PV = N kB T Number of moles: n = m/M One mole contains NA=6.022 X 1023 particles : Avogadro’s number = number of carbon atoms in 12 g of carbon m=mass M=mass of one mole