chemistry redo midterm

intermolecular forces

attractive forces between molecules that influence physical properties

intramolecular forces

bonds within a molecule, much stronger than intermolecular forces

London dispersion forces

weakest IMF, caused by temporary dipoles, present in every molecule

increase in london dispersion forces

more electrons, larges molar mass, larger surface area

dipole-dipole forces

medium IMF strength, attraction between permanant dipoles in polar molecules

hydrogen bond

strongest IMF, dipole-dipole attraction when H is bonded directly to N, O, and F

stronger hydrogen bonds

higher boiling point, melting point, viscosity, and surface tension, decreased vapor pressure

surface tension

resistence of liquids surface to being stretched

viscosity

resistance to flow

vapor pressure

decreases when intermolecular forces become stronger, fewer molecules escape into the gas phase

strong IMF and boiling point

increase bp

strong IMF and melting point

increase mp

strong IMF and vapor pressure

decrease vp

strong IMF and evaporation

decrease evp

volatile liquid

liquid that evaporates easily

capillary action

movement of liquid through narrow spaces due to adhesion and cohesion

adhesion

attraction between different substances

cohesion

attration between molecules of the same substance

heat of vaporization

energy requires to convert liquid to gas

heat of fusion

energy required to melt a solid

endothermic phase changes

melting, vaporization, sublimation

exothermic phase changes

freezing, condensation, deposition

heating curve phase change equation

q=mc* delta T

triple point

temperature and pressure where solid, liquid, and gas coexist

critical point

end of the liquid-gas equilibrium curve

supercritical fluid

substance above its critical temperature and pressure

types of solids

ionic, molecular, metallic, covalent network

ionic solids

hard, brittle, high melting point, conduct

molecular solids

soft, low melting point, poor conductor

metallic solids

malleable, ductile, excellent conductor

covalent network solids

extremely hard, very high melting points

solution

homoegenous mixture

solute

substance being dissolved

solvent

substance doing the dissolving

similar dissolves similar

polar dissolves polar, nonpolar dissolves nonpolar

hydration

water surrounding dissolved ions

unsaturated solution

can dissolve more solute

saturated solution

contains maximum solute

supersaturated solution

contains more dissolved solute than normally possible

electrolye

produces ions in solution

strong electrolyte

completely dissociates

weak electrolyte

partially ionizes

non electrolyte

produces no ions

increasing temperature and solubility of solids

increases solubility

increasing temperature and solubility of gases

decreases solubility

henry’s law

gas solubility increases with pressure

molarity

moles of solute per liter of solution

molality

moles of solute per kilogram of solvent

mass percent

mass of solute per mass solution x 100

mole fraction

moles of component / total moles

dilution equation

M1V1 = M2V2

coligative properties

depend only on number of dissolved particles

four colligative properties

vapor pressure decrease, boiling point increase, freezing point decrease, osmotic pressure

boiling point elevation

delta Tb=iKbm, find new boiling point after adding solute

delta Tb in boiling point equation

boiling point increase

Kb in boiling point equation

boiling constant

freezing point depression

delta Tf=iKfm, finding new freezing point after adding south

delta Tf in freezing point equation

freezing point decrease

Kf in freezing point equation

freezing constant

osmotic pressure equation

pi=iMRT

R variable

gas constant

van’t hoff factor, i

number of particles formed in solution

colloid

mixture with intermediate sized particles??

tyndall effect

scattering of light by colloids

micelle

spherical arrangement of soap molecules trapping grease

reaction rate

Rate = -(change [reactant or product])/change in temperature, change in concentration over time

average rate

measured over an interval of time

instantaneous rate

rate at one specific moment

factors that affect reaction rate

concentration, temperature, pressure, surface area, catalyst, nature of reactants

collision theory

particles must collide with enough energy and proper orientation

effective collision

produces products

activation energy, Ea

minimum energy needed for a reaction

transition state

highest energy point during reaction

catalyst

lowers activation energy without being consumed

rate law

Rate= k[A]^m [B]^n

m and n exponents

reaction orders

rate constant, k

constant relating concentration to reaction rate

overall reaction order

sum of exponents in the rate law

zero order rate law

rate=k

first order rate law

rate = k[A]

second order rate law

rate=k[A]²

integrated zero order equation???

[A]=[A]0 - kt

integrated first order equation??

ln[A]=ln[A]0-kt

integrated second order equation??

1/[A]=1/[A]0+kt

zero order half life??

[A]0/2k

first order half life??

0.693/k

second order half life??

1/(k[A]0)

zero order graph

[A] vs time

first order graph

ln[A] vs time

second order graph

1/[A] vs time

Arrhenius equation

k=Ae^(-Ea/RT)

frequency factor, A

number of collusions

increasing temperature and k

increases k

reaction mechanism

step by step pathway of reaction

intermediate

produced and then consumed, absent in overall equation

rate determining step

slowest step of a mechanism

molecularity

number of reactant particles in an elementary step

chemical equilibrium

forward and reverse reaction rates are equal

dynamic equilibrium

reactions copntinue but concentrations remain constant

equilibrium constant, Kc

[Products]/[Reactants], coefficients become exponents, ratio of products to reactants at equilibrium