Unit 6- The Gaseous State

Question 1

solid

Answer 1

has fixed shape and volume
units: g/cm^3 or g/mL

Question 2

liquid

Answer 2

has fixed volume but no definite shape
unit: g/mL

Question 3

gas

Answer 3

has no fixed volume or def shape
unit: g/L

Question 4

pressure

Answer 4

force per unit area exerted on a surface
unit: 1Pa = 1kg/ ms^2

Question 5

barometer

Answer 5

used to measure pressure of atmos
- height(h) = 760mm at normal atmos pressure

Question 6

manometers

Answer 6

both open and closed end manometers measure pressure diffs
- pg>pa (h=pg-pa)
- pg<pa (h=pa-pg)
- h=pg

Question 7

Boyle’s Law

Answer 7

V = k x 1/p
PV = K (if T and n are same)
*P1V1 = P2V2

Question 8

Charles’ Law

Answer 8

V = k2 x T
0K = -273.15C
T in kelvin
*V1/T1 = V2/T2

Question 9

Avogadro’s Law

Answer 9

V= k3 x n(mol)
*V1/n1 = V2/n2 (const T and P)

Question 10

Ideal Gas Law

Answer 10

PV=nRT
R= 0.08206 Latm/molK
- vol of 1 mol at STP (T=0C P=1atm) = 22.4L

Question 11

MM

Answer 11

(mass x R x T) / (P xV)

Question 12

Density

Answer 12

(MM x P) / (R x T)

Question 13

coeff

Answer 13

= L w/ const temp and pressure

Question 14

Dalton’s Law of Partial Pressures

Answer 14

Pt=Pa+Pb

Question 15

mole fraction (x, chi)

Answer 15

the # of mol of 1 component of a mix divided by the total # of mols of all substances present in the mix

Xa= na/ na + nb +nc…

Question 16

Partial Pressure

Answer 16

Pa = Xa x Pt

Question 17

Collecting gas over water

Answer 17

Pg = Pt - Ph2o

Question 18

Kinetic Molec Theory of Gases

Answer 18

1) No forces of attraction or repulsion between gas particles
2) size of gas particles can be negligible
3) No loss in KE occurs when gas particles collide
4) KE changes only if T changes

Question 19

Avg speed

Answer 19

• called the root mean square (rms) speed, Urms
• the square root of the avg squared speed

Question 20

Urms =

Answer 20

sqaure root of (3RT/ MM)
*R= 8.314 kgm^2/s^2molK
- MM= kg/mol

Question 21

Effusion

Answer 21

the passage of gas through a small hole into an evacuated space
* gases with low MM effuse more rapidly

Question 22

diffusion

Answer 22

the mixing of particles due to motion

Question 23

Graham’s Law of Effusion

Answer 23

relative rates of effusion can be used to determine MM (M)

rate of effusion A/ rate of effusion B = square root of (Mb/Ma)

Question 24

Graham’s law when equal vol or pressure of gas A and B are used

Answer 24

effusion time (t)

tb/ ta = square root of (Mb/ Ma)

Question 25

deviations from Ideal Behavior

Answer 25

at high pressures:
- ideal gas law fails
- kinetic molec theory fails (forces of attraction)
- assumption gas particles are small compared to distances between them fails

Question 26

Van der Waals Equation

Answer 26

corrects for attractive forces and vol occupied by gas molec

(P + an^2/v^2)(V-nb) = nRT
- a = const relat to strenght of attraction forces
- b = const that depends on the size of the gas particles