Phases and Phase Changes

Question 1

Describe the properties of an ionic solid

Answer 1

High melting/boilings points, poor conductivity in solid state, high conductivity in molten state or in aqueous sltn

Question 2

Describe melting point differences of pure crystalline solids vs amorphous solids

Answer 2

Pure crystalline will have sharp distinct mp, amorphous will melt over larger range

Question 3

How to read a vapor/liquid diagram for multiple components (Raoult’s law)

Answer 3

Lower curve is composition of liquid, upper curve is vapor composition above that liquid at given T

Question 4

What are colligative properties?

Answer 4

Properties of solution dependent on concentration of dissolved particles but not on chemical identity of those particles

Question 5

Explain Raoult’s law

Answer 5

P.a = X.a * Pº.a
The vapor pressure = the vapor pressure of pure solvent * mole fraction of solvent composition of the new liquid.
Only holds when attraction b/w molecules of different components = attraction b/w molecules of pure component

Question 6

Calculate boiling point elevation

Answer 6

∆T.b = i * K.b * m
K.b = proportionality constant of solvent
m = molality (mol solute/kg solvent)
i = van't Hoff factor = moles particles dissolved per mole solute molecules. i = 2 for NaCl

Question 7

Calculate freezing point depression

Answer 7

∆T.f = i * K.f * m

Question 8

Calculate osmotic pressure

Answer 8

∏ = iMRT
M = molarity of solution
i = van't Hoff factor

Question 9

Water will move to chamber of higher molarity or…

Answer 9

higher temperature