Topic 1: Gas Law

Question 1

in van der waal’s equation, what does a and b values mean

Answer 1

a: constant related to molecular interactions > present of interactions between real gas > tendency to collide with container walls decrease > pressure decrease > so must add a

b: related to molecular volume > must subtract b from Vm to account for actual free space available for gas movement

Question 2

definition of virial equation of state, Z

Answer 2

Z is the compressibility factor > tells how much real gas behaves like ideal gas

Question 3

definition of Boyle’s temperature

Answer 3

the temperature where the second virial coefficient, B goes to 0

(B goes to 0 for ideal gas)

Question 4

definition of thermal expansion coefficient, alpha

Answer 4

tells how much the substrate expands when temperature increases

Question 5

definition of isothermal compressibility, kT

Answer 5

tells how much the substrate shrinks when pressure increases

Question 6

when to use which version of R

Answer 6

when P=atm and V=L, use R = 0.08205 Latm/molk

when P=Pa and V=m^3, R = 8.314 J/molk

Question 7

for work done, when to convert units

Answer 7

P=atm and V=L, must convert L.atm to Joules: 1L.atm =101.325J

P=Pa and V=m^3, already in J, don’t need convert