Chem 106 Exam 1 2023 with verified questions and answers

Homogeneous Mixtures Composition may vary; appears to be one substance, but really contains multiple materials; most are actually solutions Aqueous Solutions Have water as solvent, and solid, liquid, or gas as the solute Solutions Homogeneous mixtures Solute The component of the solution that changes state Solvent The component that keeps its state Entropy (Delta S): The measure of energy dispersal and disorder in the system Solvent-Solute Interactions The interactions between a solvent particle and a solute particle Solvent-Solvent Interactions Interactions between a solvent particle and another solvent particle Solute-Solute Interactions Interactions between a solute particle and another solute particle Miscible Capable of being mixed; capable of mixing in any ration without separation of 2 phases Soluble When one substance (solute) dissolves in another (solvent) Insoluble When one substance does not dissolve in another Exothermic Gives off energy; typically spontaneous Endothermic Absorbs energy; reaction can also be spontaneous 3 Steps for Solution Formation 1. Separating the solute into its constituent particles (endo); 2. Separating the solvent particles from each other to make room for the solute particles (endo); 3. Mixing the solute particles with solvent particles (exo) Hydration =Ion-Dipole Interactions; when ions dissolve in water Temperature For most solids: solubility increases as T increases; Gases: more predictable as solubility decreases as temp increases Dynamic Equilibrium Rates of dissolution and depression become equal Saturated Solution Solution in which dissolved solute's in dynamic equilibrium with solid (or undissolved) solute Unsaturated Solution Solution containing equilibrium amount of solute Pressure Gas: Solubility increases as P increases Dilute Solution One containing small quantities of solute relative to amount of solvent Concentrated Solution One containing large quantities of solute relative to amount of solvent Molarity (M): amount of solute (in moles) divided by volume of solution (in liters) Molality (m): amount of solute (in moles) divided by mass of solvent (in kg) Parts by Mass Mass of solute divided by mass of solution times multiplication factor (100) Parts per Million (ppm): requires multiplication factor of 10^6 Parts per Billion (ppb): requires multiplication factor of 10^9 Parts by Volume Concentration usually ratio of solute to volume of solution, all multiplied by multiplication factor Mole Fraction (X_solute): means of expressing solution concentration as number of moles of solute per moles of solution: amount of solute (in moles) divided by the total amount os solute+solvent (in moles) Mole Percent (mol %): mole fraction times 100 Colligative Property Property that depends on the number of particles dissolved in solution, not on type of particle Ideal Solution Solution that follows Raoult's Law at all concentrations for both solute and solvent Osmosis Flow of solvent from solution of lower solute concentration to one of higher solute concentration Rate Law Between the rate of reaction and concentration of reactants Rate Constant (k) constant of proportionality Zero-Order If n=0 and rate is independent of concentration A First-Order If n=1 and rate directly proportional to concentration A Second-Order If n=2 and rate's proportional to square of concentration of A Overall Order Sum of exponents (m+n) Integrated Rate Law For chem rxn: relationship between concentration of reactants and time Average Rate Related to the slope of the line through 2 endpoints on concentration vs. time plot Instantaneous Rate Rate at a particular time Activation Energy (Ea): An energy barrier/hump that must be surmounted for reactants to be transformed into products Frequency Factor (A): number of times that reactants approach activation barrier per unit of time Exponential Factor Number between 0 and 1 that represents fraction of molecules that have enough energy to make it over activation barrier Collision Model Chem rxn occurs after sufficiently energetic collision between 2 reactant molecules Reaction Mechanism A series of individual chem steps by which an overall chem rxn occurs Elementary Step Each step in a reaction mechanism Reaction Intermediates Species that are formed in one step of a reaction mechanisms and consumed in another Catalyst Substance increases rate of chem rxn but isn't consumed by rxn Homogeneous Catalysis Catalyst exists in same phase as reactants Heterogeneous Catalysis Catalyst exists in different phase from reactants Enzymes Biological catalysts that increase normal temps. Dynamic Equilibrium For chem rxn, it's condition in which rate of forward reaction equals rate of reverse rxn Equilibrium Constant (K) for rxn defined as ration, at equilibrium, of concentration of products raised to their stoichiometric coefficients; K=products divided by reactants Law of Mass Action Relationship between balanced chem equation and expression of equilibrium constant