Day 3: Phases & Gases

Question 1

Physical Transition

Answer 1

Phase changes

Question 2

Chemical Transition

Answer 2

Combustion, changes the element

Question 3

Solid –> liquid

Answer 3

Fusion (endo)

Question 4

Liquid –> gas

Answer 4

Vaporization (endo)

Question 5

Solid –> Gas

Answer 5

Sublimation (endo)

Question 6

Gas –> Liquid

Answer 6

Condensation (exo)

Question 7

Liquid –> solid

Answer 7

crystalization (exo)

Question 8

Gas –> Solid

Answer 8

deposition (exo)

Question 9

Endothermic reactions

Answer 9

Positive entropy

positive enthalpy

Question 10

Exothermic reactions

Answer 10

Negative entropy

Negative enthalpy

Question 11

At the b.p. the atm equals the

Answer 11

vapor pressure

Question 12

Triple point

Answer 12

solid, liquid & gas meet

Question 13

Critical point

Answer 13

no more phase changes

Question 14

Ideal gas assumptions

Answer 14

1. Gas molecules themselves have no volume (good @ low pressure)
2. No inter molecular attractions between molecules (all collisions are ellastic) (Good @ high temperatures)

Question 15

Kinetic Energy Average is ∝

Answer 15

to Temperature

Not all molecules move at the same speed

Question 16

STP (standard temperature and pressure)

Answer 16

1 atm

0 dregrees celcius = 273 K

Question 17

Units for gases

Answer 17

l L = 1 cm^3 = 1 mL
Kelvin for temperature
Pressure: 1 atm = 760 torr = 760 mmHg = 101325 Pa
Energy: 8.314 J/mol * K OR 0.08206 Latm/molK
n = # mols of gas

Question 18

> Mass per volume

Answer 18

more dense

Question 19

Ideal gas law

Answer 19

PV=nRT (works best at low P, high T, and for non-polar gases)

Question 20

Boyle’s Law

Answer 20

P∝ 1/V

Question 21

Charle’s Law

Answer 21

V ∝ T, density decreases

Question 22

Avogadro’s Law

Answer 22

V ∝ n, 6.02 * 10^23 avoardo’s number

Question 23

Dalton’s partial pressure

Answer 23

Ptot = Pa+Pb..

Pa = XaPtot, Xa= mol fraction

Question 24

Grham’s Law of Effusion

Answer 24

r1/r2 = √M2/M1
Gases escape through narrow holes
Lighter gas fraction moves faster

Question 25

1 mol gas

Answer 25

22.4L @ STP

Question 26

Percent yield formula

Answer 26

% yield = (actual yield/theoretical yield) X 100

Question 27

When looking for percent yield do the following

Answer 27

Find the mold of each reactant, then put those over the coefficients in the balanced equation to find the limiting reactant Use the reactant that is limiting to calculate the theoretical yield and then solve whatever is needed