Yash Nagpal AP Chemistry Review (Thermochem/Thermodynamics (Thermodynamics…
Yash Nagpal AP Chemistry Review
Atoms can be bonded with each other in multiple ways. Covalent bonds form molecules, this is when electrons are shared between multiple atoms. Ionic bonds are when electrons are transferred from one atom to another. Metallic bonds occur when metals give up their valence electrons, so all the cations are surrounded by a sea of electrongs.
Covalent bonds result in unequal sharing of electrons when one atom is more polar than another, it spends more time on the more polar atom. Molecules have a shape based on how the lone pairs of electrons are positioned, based on the AXE formula.
The rate of the reaction always has to be determined experimentally, because it it dependent on many factors.
Reactions can be of different orders with respect to different reactants. At order 0, the reaction is not dependent on the concentration of that reactant. ln[A]t-ln[A]0=kt at order 1. This is the integrated rate law which connects concentration of the reactant to the time. 1/[A]t-1[A]0=kt at order 2
Nuclear chemistry is the study of the change of protons and neutrons in the atom.The half-life of an atom is an intrinsic property of the material. Alpha radiation is a helium nucles, beta radiation is an electron, gamma radiation is just enegy.
No reaction goes all the way, at some point it reaches equilibrium, this is when the forward reaction=reverse reaction in terms of reaction rate. K is the equilibrium constant for the reaction. Q is the current ratio of moles of product/moles of product. When Q>K, reverse reaction is preferred. When Q=K, the reaction is it at equilibrium. When Q<K, forward reaction is preferred.
Delta G= -RT lnK. Ka is the equilibrium constant of the acidic reaction that produces H+. Kb is the equilibrium constant of the basic reaction that consumes OH-. K is temperature dependent. Q is dependent on concentration, pressure, etc
Stoichiometry is especially useful for determining theoretically how much product will exist after the reaction, acc. to the ratio of chemicals in the chemical equation, also useful for how much reactant to use in the lab, depending on how much reactant one would like to use.
Stoichiometry tells us the theoretical yield of a reaction, you have to multipy the theoretical product created times percent composition to calculate the actual yield of products in a reactions.
Thermodynamics is the study of Gibb's Free Energy, Entropy, and Enthalpy. The most important equation is G=H-TS. When G is negative, the reaction will occur spontaenously and is thermodynamically favorable.
Thermochemistry is the study of change of heat in a reaction, including change in termperature based on the reaction q=mc(deltaT). It is extremely important to keep track of units and understand that energy lost in a reaction is a negative value.
The pH scale is a measure of the -log[H+]. pPOH is a measure of -log[OH-]. pH+pOH=14 at 25
C because Kw is 10^-14 and Ka
Kb=Kw. Strong acids/bases ionizes completely in water, ex. 1.0M HCl produces 1.0M H+ and 1.0M Cl-. Weak acids/bases only partially ionize in water, so 1.0M HF produces less than 1.0M H + and F- and most stays as HF.
Titrations can be calculated to determine the volume of an unknown compound. Adding a strong base to a strong acid always reaches its equivalence point at 7. A pH indicator with its endpoint at the equivalence point of the reaction is used to see how complete the reaction is.
Ideal Gas Law: PV=nRT, all gases follow this formula, except when temperature is low and pressure is high. The combined gas law is also a very important formula: P1V1/T1=P2V2/T2.
Gases follow the Kinetic Molecular Theory, which states that particles are in constant motion and cause pressure when they collide with the walls of the container.
Solutions are especially useful when different molecules and ionic compounds break down into constituent ions. Ions can become spectator ions if they ionize on botht the reactant and product side of the equation.
It its important to understand units in solutions including molarilty (mol solute/ L solution), molality (mol solute/kg solvent), parts by mass (mass solute/mass total), parts by volume (volume solute/volume total)
deltaG=-nFE. This equation can be used to tell you how thermodynamically favorable a reaction is. E is the reduction potential of both the oxidation and reduction half-reactions. E is always positive. F is Faraday's constant (96,485 coulombs per mole of electrons).
Electrons are transferred from the anode to the cathode of a Galvanic cell. Mass of the anode decreases as the metal is converted to cation and goes out to the solution. The anode and cathode solutions are connected through a salt bridge. The mass of the cathode increases as the cation is converted into more cathode.
Intermolecular forces include London dispersion focres, dipole-dipole foces, ion-dipole foces. Ion-dipole forces are the strongest forces, then dipole-dipole, then London dispersion forces. Dipole forces are based of polar covalent molecules.
Intermolecular Forces include Van Der Waals forces, which hold molecules together, and relate to its boiling point, the stronger the intermolecular forces, the higher the boiling point, and the more likely that substance is to reamin in liquid state.