Unit 3: Intermolecular Forces and Properties Flashcards
Expect to learn and review AP Chemistry's Unit 3 material. This involves a lot of information revolving around Intermolecular Forces and their Properties. Master the first 2 units before you start on this one.
Ion-Ion Forces
Attraction between oppositely charged ions. (Strongest IMF due to straight + & - attraction)
Ion-Dipole Forces
Attraction between an ion and a polar molecule. (Ex: NaCl dissolving in water)
Dipole-Dipole Forces
Attraction between polar molecules (- is attracted to +)
Hydrogen Bonding
A stronger form of Dipole-Dipole forces. Involves a polar hydrogen and a polar N, O, or F
London Dispersion Forces (LDF)
IMFs between a nonpolar molecule and something else. Induced Dipole-Induced Dipole (ID)
Ion-ID
Dipole-ID
Polarizability
Means, how easy it is to induce a dipole?
The bigger an atom, the more polarizable. (Softer)
Smaller atoms-highly nonpolarizable (Harder)
List of IMF Strength. Rank from Strongest IMFs to Weakest.
Ion-Ion (Strongest), Ion-Dipole (2nd Strongest), Hydrogen Bonding, (3rd Strongest), London Dispersion (Weakest)
H Bonds are either the strongest or the 2nd strongest.
Ionic Solids have…
Ionic Bonds, Strong Ionic forces, brittle, and high melting point. [conducts electricity when dissolved only] (ex. NaCl, MgO)
Covalent Network Solids have…
Layered networks, are Rigid, very Hard, and DO NOT conduct electricity (ex. diamond, graphite)
Strongest Covalent Forces
Forms some of the hardest things that exist.
Molecular Solids have…
weaker IMFs, are softer, and have lower melting points.
Metallic Solids have…
sea of electrons, are good conductors of heat and electricity, malleable and ductile.
Crystalline solids have…
A nice orderly, grid structure
Amorphous solids have…
a random structure.
Ideal Gas Law Equation
PV=NRT or (Pressure)(Volume) = (Moles)(Gas Constant)(Temperature)
What is Dalton’s Law of Partial Pressures
When you have a mixture of gasses, the full pressure is the sum of the partial pressures, (ex. gas collection over water)
What is the equation for Dalton’s Law of Partial Pressures.
P[total] = P[a] + P[b] + P[c]… (a, b, c are gasses. If there are more gasses in a mixture, add more Pressures (P), if less, then remove (P)s.
What is Charles’ Law
Relationship between Temperature and Volume, as Temp increases, Vol increases. Equation is [V = kT V/T = k]
What is Boyle’s Law
Relationship between Volume and Pressure. More Pressure = Lower Volume. Lower Pressure = More Volume Equation (P[1]V[1] = P[2]V[2])
What is Combined Gas Law
Combines Charles’, Boyle’s, and Gay Lusac’s Law. Used to calculate changes when other things are kept constant.
(ex. Assuming constant temp, if a 1L container of gas at a pressure of 0.32 atm is constrained to 0.25L, what is the new pressure?
Equation is (P1V2)/T1 = (P2V2)/T2)
What is Kinetic Molecular Theory
A theory that helps describes why gasses act the way they do. KMT assumes that gasses follow these rules.
*Gas moves in random directions at relatively large distances
*Collisions are perfectly elastic (no energy loss)
*Gasses move in straight lines until colliding with the side of a container
*Average Kinetic Energy of a sample of gas is proportional to Temperature.
What is a Solution?
Solutions (also known as homogenous mixtures) are a combination of any matter. (ex. NaCl and H2O)
Difference between a Solvent and a Solute?
Solvents are the largest quantity in a solution and is what is used to dissolve Solutes.
Solutes are the smallest quantity in a solution and dissolve in in the Solvent
What is Solvation?
The process of mixing a solvent and solute.
Equation for Object in motion. (May come in handy)
K = 1/2 (mv) squared
Kinetic Energy = 1/2 (mass x velocity)[squared]
What do Maxwell Boltzmann Diagrams show
Shows distribution of molecules moving at a certain speed.
When do gasses differ from Ideal Gas Law
When gasses are at…
*High Pressure, gas molecules start to take up more space
*Low Temperature, IMFs start to take effect
…they start to differ from the Ideal Gas Law. This is called Van der Waals equation (Likely will never ever be used in AP Chemistry).
What is Molarity?
Molarity is the measure of a solute’s concentration in a solution.
Molarity Equation= Moles of solute /Liters in solute, M = m/L
*Basically moles per liter
What is a Suspension or Mechanical Mixture?
A heterogenous mixture of two or more substances, (ex. sand and water)
What are the properties of a Suspension/Mechanical Mixture
*Sizes, shapes, and concentrations of particles can vary in a Suspension.
*Macroscopic properties are different at different locations within the sample.
*In some cases, components can be separated through filtration.
What are the properties of a Solution or Homogenous Mixture?
*Have a mix of 2 or more substances
*Macroscopic properties do not vary within sample
*Components cannot be separated through filtration
*Components can be separated by methods that alter IMFs
*No components are large enough to scatter visible light
When does a Solution become a Saturated Solution?
When the solvent has dissolved the max amount of solute possible at a certain temp, and some solid particles remain undissolved. Becomes an equilibrium system where solid particles continually dissolve in the solvent and dissolved particles fall out of the solution.
What are 3 different types of Solutions?
Liquid Solutions, Solid Solutions, and Gas??? Check
Properties of Solid-Liquid Solutions
*Many ionic compounds dissolve in polar solvents (ion-dipole)
*Polar solids, such as glucose, dissolve in polar solvents (dipole-dipole or H-bonds)
*Nonpolar solids, such as mothballs dissolve in nonpolar solvents (dispersion
What are the Properties of Steel?
*Pure Iron lacks directional bonds
*Steel is more rigid, less malleable, and less ductile than pure iron because of stronger directional bonds between C and Fe
*Density of Steel is greater than that of pure Fe, as interstitial atoms do not expand by much
What are 2 equations that express concentration?
Molarity (M) = moles solute / liters solution
Or…
mole fraction = X[a] = moles A / moles A + moles B + moles…
*note, molarity can change with temperature, mole fractions do not change with temperature.
What do Particulate models do?
Particulate models represent interactions between components of a mixture, like…
Ion sizes and orientation of solute ions and solvent particles
and represent concentrations of components.
What is Dilution
decreasing concentration by adding solvent (typically water)
M1V1 = M2V2
What is Distillation
Distillation separates mixtures by taking advantage of boiling points and differences in vapor pressure.
(ex, 1 liquid A boils at 70 C, Liquid B at 700 C, Liquid A will evaporate first, being collected as a vapor, separating the liquids.)
What is Paper Chromatography
Paper Chromatography separates mixtures by taking off polarity and non polarity.
What are the Solubility Rules you should know
*Group 1A elements are Na+, K+ etc
*Salts of nitrate and ammonium
*Hydroxide + IA or IIA
*Silver compounds usually insoluble
*Cl-, Br-, I-, exceptions, Ag+, Pb2+, Hg
*Memorizing these aren’t too important
*“Like dissolves like” - Ms. Horgan
Polar solvents dissolve polar solvents, nonpolar solvents dissolve nonpolar solvents
Shorter wavelengths have ___ frequency and ___ energy
Shorter wavelengths have higher frequency and higher energy
Longer wavelengths have ___ frequency and ___ energy
Longer wavelengths have lower frequency and lower energy
Equations for Light
h= Planck’s Constant = 6.626 x 10 (-34 exponent) Js
Light Quantification equation?
E = hv
Energy of a Photon = Planck’s constant x energy.
Do different color lights have different energies and properties?
Yes. Red lights have lowest energy, Green and Blue have most.
What is Beer’s Law of Absorption?
Relationship between chemical solution and absorption of light. concentration of chemical solution is directly proportional to absorption of light
Equation is A=abc
*A=Absorption
*a=molar absorptivity
b=path length
c= solute
Used to find concentrations.
