Chem 2

• Matter is anything that takes up space and has mass, and energy is what makes the matter move.
• Matter is made up of atoms, the smallest particle, and molecules, formed by the combination of two or more atoms.
• Matter possesses energy and can exist in various states such as solid, liquid, gas, and other states of matter.
• Changes in temperature and pressure can change the phase of matter, releasing or requiring energy.
• Matter is made up of tiny particles known as atoms, which are in constant motion and possess kinetic energy.
• There is a transfer of energy between particles (atoms & molecules) as these particles collide with each other.
• Molecular motion is greatest in gases, less in liquids, and least in solids.
• The kinetic molecular model is used to explain why states of matter differ in movements and arrangements.
• The kinetic molecular model describes the forces between molecules and the energy that they possess.
• The kinetic molecular model also describes the effects of temperature and pressure on matter.
• Intramolecular forces, or forces within a molecule, can hold particles together and are not strongly affected by physical changes.
• Intermolecular forces, or forces between molecules, can hold together identical particles and are strongly affected by physical changes.
• Intermolecular forces exist among all the particles that compose matter and are responsible for the very existence of the condensed states (solid & liquid).
• The equilibrium constant can be used to qualitatively interpret the direction of the reaction as it approaches equilibrium.
• A heterogeneous equilibrium is an equilibrium involving reactants and products in more than one phase, for example, the reaction of iron metal filings with steam to produce iron oxide, which involves solid phases, Fe and 𝑒3��4, in addition to gaseous phases.
• For catalytic methanation, 𝑄𝑐 = [��𝐻4]𝑖[𝐻2��]𝑖[𝐶𝑂]𝑖[𝐻2], where the concentrations of the gaseous mixture are substituted.
• A homogeneous equilibrium is an equilibrium that involves reactants and products in a single phase, for example, catalytic methanation, which involves only gaseous reactants and products.
• The reaction quotient, Qc, is an expression that has the same form as the equilibrium-constant expression but whose concentration values are not necessarily those at equilibrium.
• K ≈ 1 indicates that neither direction of the reaction is favored, and the forward reaction proceeds about halfway.
• K > 1 indicates that the forward reaction is favored, and the forward reaction proceeds essentially to completion.
• Stoichiometric calculations for reactions in solution can be performed using different ways of expressing concentration of solutions.
• All three interactions between solute and solvent are of similar magnitude, and the two substances are soluble in each other in all proportions, making them miscible.
• Types of solutions include gaseous solution, aqueous solution, and solid solution.
• The rule of thumb that like dissolves like states that similar kinds of solvents dissolve similar kinds of solutes.
• A solution does not form when hexane and water are mixed.
• The majority component of a solution is usually called the solvent, while the minority component is usually called the solute.
• Entropy is a measure of energy randomization or energy dispersal in a system.
• Different ways of expressing concentration of solutions include percent by mass, mole fraction, molality, molarity, percent by volume, and percent by mass.
• Solubility is the amount of a substance that dissolves in a given amount of solvent.
• The solubility of a substance in another depends on nature’s tendency toward mixing and on the types of intermolecular forces.
• Neon and argon are separated by a barrier, but when the barrier is removed, the two gases spontaneously mix to form a uniform solution.
• Intermolecular forces may either promote or prevent the formation of a solution, depending on the nature of the forces in the particular combination of solute and solvent.
• Nature’s tendency toward mixing causes a flow of water out of the body’s cells and into the seawater.
• The state of matter depends on the magnitude of intermolecular forces among the constituent particles relative to the amount of thermal energy in the sample.
• Water is less dense as a solid than it is as a liquid, allowing ice to float on water.
• The three-dimensional structure of ice keeps water molecules farther apart than they are in liquid water.
• The water molecule in ice are less closely packed together than in liquid water, creating more spaces between the molecules.
• Reactions usually speed up when the temperature increases.
• Maxwell-Boltzmann Distribution is a plot of the number of particles vs a particular energy.
• Collision Theory assumes that, for reaction to occur, reactant molecules must collide with an energy greater than some minimum value and with the proper orientation.