Exam 1 Flashcards
ch 10, 11
What are the 3 main types of IMFs?
London forces, dipole-dipole, hydrogen bonding
Electrostatic attractions between + and - charges
Intermolecular Forces (IMFs)
All matter meets the requirements for attraction due to temporary dipoles
Stronger the more massive the particle/molecule and the greater its surface area
London Forces
Requires polar molecules with permanent dipoles
The more polar the molecule, the stronger this force is
Dipole-Dipole
Requires a grouping within the molecule of O–H, N–H, or F–H and available nonbonding/lone pair electrons on the other molecule
O–H is more electronegative than N–H
Hydrogen Bonding
Requires ions and polar (solvent) molecules
Ion-Dipole Forces
The ability of atoms in a molecule to attract bonding electrons to themselves
Electronegativity
Results from the relative positions of the actual bonds between atoms within the electronic geometry
Molecular Geometry
Extended networks of atoms held together by metallic bonding (Cu, Fe)
Metallic Solids
Extended networks of ions held together by ion-ion interactions (NaCl, MgO)
Ionic Solids
Extended network of atoms held together by covalent bonds (C, Si)
Covalent Network Solids
Ions are mobile in solution
Electrolytes
Homogeneous mixtures on a molecular level
Solutions
Component that determines the phase of the solution
-Usually present in the largest quantity
Solvent
Material(s) that is/are dissolved
Solute
(mass of component/total mass of sol’n)(100/1)
Mass Percent
moles of desired component/total moles
Mole Fraction
moles solute/L solution
Molarity
moles solute/kg solvent
Molality
The limit of solute that will dissolve in a solvent has been reached, no more added solute will dissolve
Saturated Solution
Holds more solute than required for a saturated solution, these are unstable
Supersaturated Solution
Occurs when industrial users take water from a river or lake, and return it (no matter how clean) at a higher temperature
Thermal Pollution
(constant given for gas M/atm)(partial pressure of same gas above the solution atm)
Henry’s Law, solubility of gas in solution (M)
Physical properties of solutions that depend only on the number of solute particles in solution, not on their nature (vapor pressure and freezing point depression, boiling point elevation, osmotic pressure)
Colligative Properties
The pressure exerted by a vapor in equilibrium with the liquid phase
Vapor Pressure
When we add a non-volatile solute to a solvent, we see a ?? of the vapor pressure, since we have effectively decreased the fraction of molecules in the entire sample with any “escaping ability”
lowering/depression
(mole fraction)(vapor pressure of pure solvent solution at a given temp)
Vapor pressure of solution, Raoult’s Law
Method: boil mixture, collect vapor, condense it
Distillation
(boiling point elevation constant)(solute molality)
Boiling Point Elevation
(freezing point depression constant for solvent)(molality)
Freezing Point Depression
The net movement of water molecules from the less concentrated solution towards the more concentrated solution
Osmosis
The pressure required to stop osmosis between a pure solvent and a solution
Osmotic Pressure
(M)(0.0821Latmmol^-1K^-1)(temp in kelvins)
Osmotic Pressure
The ratio of the actual value of a colligative property to the value calculated, assuming the substance to be a nonelectrolyte
Van’t Hoff Factor
Suspensions of particles larger than individual ions or molecules, but too small to settle out by gravity (ie: snowglobe)
Colloids
Colloidal suspensions can scatter rays of light
Tyndall Effect
if plot of 1/[A] vs t, linear, slope=k
Second Order
if plot of ln[A] vs t, linear, slope=-k
First Order
if plot of [A] vs t, linear, slope=k
Zero Order
The rate constant; it is the proportionality constant between reaction rate and reactant concentration
k
A mathematical statement of the way in which rate changes with changing concentration of reactants
Rate Law
Usual units for rate?
Ms^-1
The order to determine rates of reactions, we need to be able to measure ?,as they are changing
concentrations
The change in concentration of reactants or products with time
Reaction Rate
What are the 4 factors that influence the rates of chemical reactions?
- Nature of the products and reactants
- Temperature
- Other agents and catalysts
- Concentration of the reactants
Reaction rate depends on what 3 things?
Collision frequency, collision energy, collision orientation
The constants Kb and Kf, related to freezing point depression and boiling point elevation, are properties of: a. solutions
b. solvents
c. solutes
d. solids
b. solvents
Which does not favor solubility of a solid solute in a liquid solvent?
a. weak solute-solute interactions
b. strong solute-solvent interactions
c. increase in disorder of the system
d. covalent network bonding in solute
e. solution lower in energy that solute and solvent
d. covalent network bonding in solute
