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GENERAL CHEMISTRY SESSION 9-14 image, Freya Medelline - 23010050 Fringky…

- - - - S Orbital
      - P Orbital
      - D Orbital
      - F Orbital
    - - Valence-bond (VB) theory : Electrons of two atoms begin to occupy/share the same space (Overlap).
      - Hybridization
        
        mixing of atomic orbitals within an atom to produce new hybrid orbitals.
      - Formation of sp hybrid orbitals
      - Formation of sp2 hybrid orbitals
      - Formation of sp3 hybrid orbitals
      - Directional properties of hybrid orbitals formed
      - Two form of Overlap
        
        Sigma (σ) bond
        
        Pi (π) bond
    - - Homonuclear diatomic molecules
      - Bond Order
- - - - time needed for reactants to disappear and products to form
        
        influenced by:
        
        Chemical nature of reactants. sodium reacts quickly with water as it loses electrons easily
        
        Ability of reactant to meet. larger surface area, faster rate of reaction
        
        Concentration of reactant. higher concentration, higher rate of reaction
        
        Temperature of system. higher temperature, higher rate of reaction
        
        Present of catalyst. if catalyst is present, rate of reaction increases.
      - instantaneous rate of x. Dependent of coefficient, Dependent of coefficient
      - initial rate of reaction. Independent of coefficient, Calculated when the time is 0
      - rate law: A + B= Product, rate=K[A]^m[B]^n
        
        An exponent in a rate law is called the order of the reaction with respect to the corresponding reactant, it determines how the reaction rate is affected by the concentration of that reactant.
        
        K values indicates how fast a reaction proceeds. large K, faster reaction. Small K, slower reaction
      - Half life= the amount of time required for half of the reactant to disappear.
    - - the rate of a reaction is proportional to the number of effective collisions per second
        among reactant molecules.
      - an effective collision is one that actually gives product molecules.
        
        the particles must have a certain amount of kinetic energy called activation energy for the collision to happen.
        
        temperature also effects the particle by providing more energy, thus more effective collision will occur.
    - - a transition state between reactant and product. a potential energy diagram is used to visualize the transition energy theory.
        
        endothermic reaction has higher potential energy for its product than its reactant.
        
        exothermic reaction has higher potential energy for its reactant that its product.
    - - The energy required to initiate a chemical reaction
      - catalyst is a substance that speed up the chemical reaction without itself being used up by decreasing the activation energy
- - - - Chemical/Dynamic Equilibrium
        
        Reversible Reactions
        
        A reaction which occurs in both the forward and reverse direction.
        
        utilizes
        double arrows "⇌"
        
        Equal rates of forward and backward reaction.
        
        Concentration of reactants and products remain constant.
      - Chemical Equilibrium Constant
        
        The molar concentrations of products divided by the molar concentrations of reactants at equilibrium.
        
        Interpreting Kc values
        
        Kc ≈ 1:
        Equilibrium lies midway, as reactant and product concentration are approximately equal.
        
        Kc << 1: Equilibrium lies far towards the reactant side with little product formation.
        
        Kc >> 1: Equilibrium lies far towards the products side to completion.
        
        Direction Changes of Equilibrium
        
        When a reaction proceeds in the reverse direction, K'c (new Kc value) refers to 1/Kc.
        
        Equilibrium Law
        
        Homogenous Reactions
        
        A chemical reaction in which the reactants and products are of the same phase.
        
        Heterogeneous reaction
        
        A chemical reaction in which the reactants and products are of a different phase.
        
        Pure solids and liquids with a constant ratio of the amount of substance to its volume are not included (replaced with 1) in the Kc equation of heterogeneous equilibriums.
        
        The Kc equation only includes substances in the aqueous or gaseous state
      - Predicting the Direction of Net Reaction
        
        Qc possess the same form as Kc but the actual instead of the equilibrium concentration is utilized.
        
        Qc = Kc: Equilibrium is achieved, in which there is no net reaction.
        
        Qc < Kc: Equilibrium shifts to the product side. There is a net forward reaction.
        
        Qc > Kc: Equilibrium shifts to the reactant side. There is a net backward reaction.
    - - When changes are made to the factors affecting the system at dynamic equilibrium, the equilibrium shifts to minimize and counteract these changes.
      - Factors
        
        Temperature
        
        Increase: equilibrium shifts to the endothermic direction that absorbs heat energy (ΔH: positive)
        
        Decrease: equilibrium shifts to the exothermic direction that releases heat energy (ΔH: negative)
        
        Pressure
        
        When volume decreases, pressure increases.
        
        Increase: equilibrium shifts to the direction with less moles of substances in the gaseous phase
        
        Decrease: equilibrium shifts to the direction with greater moles of substances in the gaseous phase
        
        Presence of Catalysts
        
        A catalysts increases the rate of reaction without itself being changed.
        
        Kc is unaffected by catalysts, since it is utilized only to increase the rate at which the reaction reaches equilibrium.
        
        Concentration
        
        Substance removed: reaction occurs to replace the substance, by shifting the equilibrium towards it
        
        Substance added: reaction occurs to consume the substance by shifting the equilibrium away from it
- - - - Unsaturated solutions are solutions that have not dissolved the maximum amount of solute at a certain temperature and pressure
      - Saturated solutions are solutions that have dissolved the maximum amount of solute at a certain temperature and pressure
      - Supersaturated solutions contain more solute than maximum through heating. Addition of solute may form crystals resulting in precipitation
    - - Temperature
        
        Solubility generally increases as temperature rises
      - Solvent
        
        Polar/ionic solvents dissolve polar/ionic solutes and non-polar solvents dissolve non-polar solutes
      - Common ion effect
        
        Common Ions reduce solubility
      - pH
        
        affects solubility of ionic compounds
      - Formation of complex ion
        
        Formations of complex ions increases solubility
      - Pressure
        
        Increasing pressure increases solubility (only applicable to gases)
    - - Dynamic Equilibrium in saturated solutions
        
        occurs when the rate of solute dissolution is equal to the rate of precipitation
      - Ksp value determination
        
        Higher Ksp value equals a higher solubility of a substance
        
        Molar solubility
      - Predicting formation of precipitation
        
        Precipitation occurs when concentration of solute exceeds solubility of solvent (e.g. supersaturated solutions)
        
        Q value (reaction quotient) is used to predict precipitation
        
        If Q = Ksp then no precipitation occurs
        
        If Q < Ksp then no precipitation occurs
        
        If Q > Ksp then precipitation occurs
      - Selective precipitation
        
        Solvent bind with solutes with the higher solubility first, once no solvent is left, lower solubility solutes precipitate
    - - Quantitative analysis
        
        Determines the amount of concentration of a substance in a sample, the purity of the substance
      - Qualitative analysis
        
        Determines the identity or composition of a substance, used to detect the presence or absence of certain elements, compounds, or ions
        
        Separates and identifies anions and cations
- - - - Intermolecular forces: attraction between molecules
        
        Intramolecular forces: chemical bonds that hold molecules together
      - Van der Waals forces is attraction between partial positive and negative electrical charges molecules that are very close to each other.
        
        London Dispersion Forces (LDF)
        
        Interaction between non-polar molecules
        
        Strength relative to covalent bond varies and depends on molecules properties (weakest)
        
        Hydrogen Bonding
        
        Interaction between polar molecules containing H-F, N-H,
        and O-H bonds
        
        Dipole-Dipole Attractions
        
        Interaction between polar molecules with dipole
        
        Ion-Dipole Attractions
        
        Interaction between ionic compounds and polar molecules
        
        Ion-Induced Dipole Attractions
        
        Interaction of an ion that creates dipole with another ion or a molecule
        
        Strength relative to covalent bond varies, it depends on ion charge and polarity of neighbor particle
        
        Are ions present?
        
        Yes
        
        Are Polar Molecules present?
        
        No
        
        Ionic Bonding
        
        1 more item...
        
        Yes
        
        Ion-Dipole Forces
        
        1 more item...
        
        No
        
        Are polar molecules present?
        
        No
        
        London Dispersion Forces
        
        1 more item...
        
        Yes
        
        Are H atoms bonded to F, O, or N atoms?
        
        2 more items...
    - - Properties of matters influenced
        by intermolecular forces
        
        Tightness of packing
        
        Compressibility
        
        Ability of substrate to be compressed to smaller volume
        
        Gas compress easily
        Solid and Liquid are incompressible
        
        Diffusion
        
        Ability of molecules to move
        from one position to another
        
        Gases diffuse rapidly
        Liquids diffuse slower
        Solids do not diffuse
        
        Strength of intermolecular attractions
        
        Surface Tension
        
        Tendency of liquid to form shape
        with minimum surface area
        
        Smallest surface area possible is spherical shape
        
        Potential energy decreases,
        system is more stable
        
        Wetting of surface
        
        spreading of liquid to form thin film
        
        Intermolecular attractions between liquid and surface must be equal with attraction within liquid
        
        Volume and Shape Retention
        
        Gas can change its shape and volume based on container
        Liquids maintain volume but not fixed shape
        Solids retain volume and shape
        
        Ability of substances to maintain
        its shape and volume
        
        Viscosity
        
        Properties of liquid to resist change in form
        
        It is influenced by intermolecular attractions, molecular shape and size, and temperature
        
        Stronger intermolecular attraction
        means stronger viscosity (more viscous)
        
        Long and entangling molecules are more viscous
        
        Temperature decreases, viscosity increases
        Temperature increases, viscosity decreases
        
        High viscosity
        
        Low viscosity
    - - Changes of state in solids, liquids, and gases
        
        Evaporation
        (Liquid to Gas)
        
        Fusion (Melting)
        (Solid to Liquid)
        
        Freezing
        (Liquid to Solid)
        
        Condensation
        (Gas to Liquid)
        
        Sublimation
        (Solid to Gas)
        
        Deposition
        (Gas to Solid)
      - Dynamic Equilibrium
        
        Melting
        
        as long as no heat is added or removed, melting and freezing occur at equal rates
        
        Boiling point (liquid's vapor pressure = atm), high boiling point means there is strong molecular attractions because of the low vapor pressure. Boiling point depends on atm
        
        Sublimation
        
        Molecules evaporate from solid same rate as molecules condense from vapor
        
        Evaporation
        
        Before equilibrium: Rate of evaporation >> rate of condensation
        At equilibrium: Rate of evaporation = Rate of condensation
        
        Evaporation rate depends on: Liquid's surface area, temperature, and intermolecular attraction strength
        
        Vapor pressure (caused by molecules in vapor state), at equilibrium concentration of molecules in vapor remain constant and vapor exert constant pressure
        
        Its affected by both temperature (increase = vapor pressure increase) and intermolecular forces (strong = low vapor pressure)
      - Energy and state of changes
      - Le Chatelier's principle = when a system disrupted by stress, the system will respond in a direction that tends to counteract the disturbance, and if possible restore the equilibrium
        
        Phase change diagram
    - - Crystals
        
        Molecular crystal
        
        Ionic crystal
        
        Metallic crystal
        
        Covalent crystal
- - - - Miscible
        
        Like Dissolve Like
      - Immiscible
    - - Solvation
        
        by water molecules: Hydration
      - Dislodging
        
        Dissolution ΔHsoln
        
        Solubilty and Temperature
        
        Solute (Undissolved) + 𝑆𝑜𝑙𝑣𝑒𝑛𝑡 ⇋ 𝑆𝑜𝑙𝑢𝑡e (Dissolved)
        
        Solubility and Pressure
        
        𝐺𝑎𝑠 + 𝑆𝑜𝑙𝑣𝑒𝑛𝑡 ⇋ 𝑆𝑜𝑙𝑢𝑡𝑖𝑜n
        
        Henry's Law
        Cgas = kHPgas (T is constant)
        
        Temperature independent concentration
        
        Percent concentration
        
        Molal concetration
        
        Mole fraction
        
        Solution of solid in liquid
        
        Solution of liquid in liquid
    - - Vapour pressure depression
      - Freezing point depression
      - Boiling point elevation
      - Osmotic pressure elevation