experiment 3-4 concepts Flashcards
molecules in solid and liquid states are held together by ______________ forces
intermolecular forces
2 general types of intermolecular forces
- London Dispersion Forces
- Dipole-dipole Forces
Forces found in NON-POLAR MOLECULES and POLAR MOLECULES
NPM - LDF
PM - DDF and LDF
Special type of DDF
Hydrogen Bonding
In hydrogen boding, what is attached to H
O, N, F
what is the energy needed to increase the surface area of a liquid by one unit
Surface Tension
Unbalanced/Balanced IMFA in the surface of liquids cause surface tensions
Unbalanced
Unbalanced/Balanced IMFA causes surface tension
Unbalanced
Effect of IMFA on Melting and Freezing Point
Stronger = Higher
What type of net force do IMFA create on surface of liquids
Inward Net Force
Effect of IMFA on Melting/Freezing Point
Stronger IMFA = High MP and FP
What states exist in equilibrium at Melting and Freezing Point temperatures
solid and liquid
What must be supplied to solids to turn into liquid and why
ENERGY - break IMFA
What will be used to determine the ff:
- Melting Point
- Freezing Point
- Melting Point Determination Apparatus
- Cooling Curve
Relationship of KE and Temperature in Freezing
Direct Relationship
What is PE in Freezing
Stored Energy in Chemical Bonds
What are COLLIGATIVE PROPERTIES
DEPENDS on molarity of solute present (not on nature)
Freezing Point Lowering Formula
T solvent - T solution = kf m
where:
Tfo = freezing point of the pure solvent
Tf = freezing point of solution
kf = freezing point depression constant of the solvent
m = molality of the solution
Molality formula
m = T solvent - T solution / kf
Molar Mass Solute formula
MM = [(mass solute)(kf) / (T solvent - T solution)(kg solvent)]
Molarity VS Molality
Molarity = moles solute / Liter solution
Molality = moles solute / kg solvent
“Arrest” VS “Break” Temperature
A: plateau during phase change
B: downward slope after phase change
Downward slope and Plateau Description (KE and PE)
DS: KE decreases, PE constant
CS: PE decreases, KE constant
Sensible vs Latent Heat
S: energy required to change the temperature of the substance with no phase change.
L: energy absorbed or released by a substance during phase change
3 cooling curve variations
- no distinct plateu
- no distinct plateu
get average of first and last point right before downward slopw
Reason for Cooling Curve 1 and 2
Impurities interrupt the organized crystal packing during solidification
Two general types of IMFA
and what do you collectively call these 2
London Dispersion Forces
dipole-dipole forces
van der Waals forces
compounds ending with -one contains what type of bonding
no hydrogen bonding
