Exam 1 Flashcards
Molality
moles of solute/mass of solvent in kg
Properties of ionic compounds
- High melting points
- Hard and brittle
- Do not conduct electricity in solid form, do conduct it in molten form
- Solutions are soluble in polar solvents and conduct electricity
Finding 🔼Hsolution from 🔼Hlattice
🔼Hlattice>0: 🔼Hsol=🔼Hhydration+🔼Hlattice
🔼Hlattice<0: 🔼Hsol=🔼Hhydration-🔼Hlattice
Finding 🔼Hlattice from 🔼Hf
🔼Hlattice=🔼Hf(products-reactants)
🔼Hlattice trend
Bigger charge different and higher up on periodic table=higher 🔼Hlattice
Lattice enthalpy
Energy change that occurs when 2 gaseous atoms come together to form a solid compound
Lattice enthalpy trend
Bigger difference in charges=bigger lattice enthalpy
if theyre the same then
Smaller radius=large lattice enthalpyp
Under which conditions are gases more soluble in water?
High pressure, low temperature
Ion-dipole interaction
Interaction of ions with polar solvents
dipole dipole interactions
attractive force between polar molecules
dipole-induced dipole
attraction caused by proximity of polar molecule
Equation associated with 🔼Hhydration(+1 and +2 charges)
M+(g) + X-(g)▶️M+(aq) + X-(aq)
M2+(g) + 2X-(g)➡️M2+(aq) + 2X-(aq)
🔼Hhydration trends
Smaller ions and ions with higher charges have greater 🔼Hhydration
Factors affecting vapor pressure and their trends
- Temperature: As temp increases, KE and therefore vapor pressure increases
- Intermolecular forces: Stronger forces=higher KE needed to enter gas phase, decreasing vapor pressure
- Presence of nonvolatile solute: Affects rate of evaporation, decreases vapor pressure of solution compared to pure solvent
Raoult’s law
Psolvent=xsolvent,l•p*solvent
Psolvent=partial pressure exerted by solvent vapor above a solution
xsolvent,l= mole fraction of solvent in a liquid phase
P*solvent=vapor pressure of pure solvent
What are ideal solutions formed by?
Substances with similar intermolecular forces and similar structures. They are formed as a result of increased entropy
Ideal solution
Solution that obeys Raoultms law, 🔼Hsol=0
Volatile
measure of how easily something evaporates. more volatile components evaporate more easily
How to read graphs of boiling points of solute-solvents?
- Contant temp: Area above both lines is liquid, area in between is vapor and liquid, and area below is a vapor
- Constant pressure: Area below both lines is liquid, area in between is vapor and liquid, and area above both lines is a vapor
When do vapor pressure deviate negatively and positively from ideal behavior?
- Negative deviation: solute-solvent interactions and stronger than solvent-solvent interactions and prevent solvent from escaping solution
- Positive deviation: solute-solvent interactions are weaker than solvent-solvent interactions. Interactions of solvent molecules are disrupted and makes it easier to escape into vapor state
Colligative properties
properties that depend on the total concentration of solute particles in a solution and not their identity or other factors
Vapor pressure lowering
the difference between vapor pressure with and without a solute, proportional to the mole fraction of a solute
How do nonvolatile solutes effect vapor pressure?
They decrease it
🔼Hlattice enthalpy equation
M+(g) + X-(g)▶️MX(s) when 🔼Hlattice is negative and bonds are forming
MX(s)▶️M+(g)+X-(g) when
🔼Hlattice is positive and bonds are breaking