Jahnavi Raman Period 1 semester 2

empirical

gas

thermo

lowest whole number ratio of atoms in a compound

  1. percent to mass 2. mass to mole 3. divide by small 4. multiply till whole

molecular formula

true number of atoms of each element in a formula of a compound

ionic compound formulas are always empirical

combustion analysis

used when elements making up a substance are carbon, hydrogen, oxygen, and sometimes nitrogen

  1. determine mass of each element present in original compound (ex. carbon in CO2, hydrogen in H2O, and sometimes nitrogen in compounds such as NH, N2, N, NO2, etc)
  2. mass to mole 3. divide by small 4. multiply till whole

nature of gases

pressure

laws

STP

gas behavior

  1. they expand to fill their containers 2. they are fluid-they flow 3. they have a low density (1/1000 the density of the equivalent liquid or solid) 4. gases are compressible 5. gases effuse and diffuse

caused by collisions of molecules with the walls of a container, equal to force/unit area, SI units: Newton/meter squared = Pascal (Pa)

Boyle's law

pressure is inversely proportional to volume when temperature is held constant: P1V1=P2V2

Charles' Law

volume and temperature have a direct relationship: V1/T1 = V2/T2

Gay Lussac's Law

pressure and temperature have a direct relationship: P1/T1 = P2/T2

Avogadro's law

volume is directly proportional to the number of moles in a gas: V1/n1 = V2/n2

Dalton's law of partial pressures

Ptotal = P1 + P2 + P3 + ...

ideal gas law

PV = nRT, where R is a gas constant (0.08206 for atm, 8.314 for KPa, and 62.4 for torr

standard temperature pressure

Pressure: 1 atm, 760 torr, 101.325 KPa

temperature: 273 Kelvin

molar volume: 22.42 L

ideal gases- kinetic molecular theory

real gases experience intermolecular attractions, have volume, and don't have elastic collisions, gases likely to behave ideally have high temp and low pressure in addition to small nonpolar gas molecules

imaginary gases fitting all assumptions: collisions are elastic, gases have tiny particles far away frm each other, no kinetic energy lost, no force of attraction between particles

combined gas law: P1V1/T1 = P2V2/T2

density: D = MP/RT

gas stoich: if reactants and products are @ same conditions, mole ratios of gases are also volume ratios

calculating heat energy absorbed or released: q = mcΔT

joule is the basic unit for measuring heat

calorie: heat required to raise temperature of 1 g of water by 1 degree C

kinetic energy: energy of motion

enthalpy: amt of heat energy released/absorbed during a process

specific heat: amt of heat required to raise temperature of base unit of a substance by 1 degrees C

calorimetry: amt of heat absorbed/released during physical/chemical change can be measured, usually by the change in temp of known quantity of water in calorimeter

phase diagram: represents phases as a function of temperature and pressure

solutions

kinetics

equilibrium

homogenous mixtures

water is the universal solvent, but it can also be a solute

saturation

saturated solution: maximum amount of solute dissolved

unsaturated solution: less than maximum amt of solute dissolved

supersaturated solution: more than the maximum amt of solute is dissolved

calculations

mass percent/composition: ratio of mass units of solute to mass units of solution, expressed as a percent
(mass of solute/mass of solution) x 100

parts per million/billion (ppm/ppb): of parts of solute to 1 million parts of solutions, usually applied to very dilute solutions with very low concentrations
(mass of solute/mass of solution) x 1,000,000

grams/liter: expresses solubility, ratio of mass units of solute/volume of solution (L)
(mass of solute/volume of solution)

mole fraction: ratio of moles of solute to total moles of solution Xa=(n a/n a + n b)

molarity: ratio of moles of solute to L of solution mol/L = M = (moles of solute/liters of solution)

chemical kinetics is the area of chemistry that concerns reaction rates

collision model

rate laws

factors affecting rate

chemical equilibrium is when the rate of the forward reaction equals the rate of the reverse reaction and the concentration of products and reactants remains unchanged

LeChatelier's principle

reversible reactions are chemical reactions where the products can react to re-form the reactants

law of mass action

product favored equilibrium

reactant favored equilibrium

reaction quotient is Q, equilibrium constant is K

the key idea is that molecules must collide to react. however, only a small fraction of collisions produces a reaction

this is because collisions must have sufficient energy to produce the reaction (must equal/exceed activation energy)

colliding particles must be correctly oriented to one another in order to produce a reaction

reaction rate

differential rate laws that express or reveal the relationship between the concentration of reactants and the rate of reaction

change in concentration of a reactant of product per unit of time
rate = ([A] at time t2 - [A] at time t1 / t2-t1)

increasing temperature: always increases the rate of a reaction

  • particles collide more frequently
  • particles collide more energetically

increasing surface area: increases the rate of a reaction by increasing collisions

increasing concentration: usually increases the rate of a reaction

  • particles collide more frequently

presence of catalysts: they lower the activation energy by providing alternate pathways

if Q > K, the system shifts to the left, consuming products

if Q < K, the system shifts to the right, consuming reactants

large values for K signifies that the reaction is "product favored", in other words, the system shifts to the right. when equilibrium is achieved, most of the reactant have been converted into product

small values K signifies that the reaction is "reactant favored", n other words, the system shifts to the left.

equilibrium expression which looks like this K=[C]^l [D]^m / [A]^j [B]^k

equilibrium expression for a reaction is the reciprocal for a reaction written in reverse

acids and bases

reactions

properties/facts

models

acids

bases

low pH, conduct electricity, sour, juices and fruits, common as aqueous and liquids

bitter, slippery, cleaning products, high pH

arrhenius

bronsted-lowry

lewis acid model

acids produce hydrogen ions, while bases produce hydroxide ions

acids are proton donors while bases are proton acceptors

acids are electron acceptors while bases are electron donors

neutralization

dissociation

acid base neutralization reactions produce a salt and water

conjugate acid forms when base gains a proton, conjugate base forms when acid loses a proton

either dissociates with or without water as a reactant

strong acids dissociate completely, weak acids dissociate slightly, so ICE tables are required to find concentration at equilibrium and pH

to find pH: -log[H3O+] to find pOH: -log[OH-]