Oceans

• Solubility is due to the intermolecular forces between the solute and solvent therefore, polar molecules are more soluble in polar solvents and vice versa
• Lattice enthalpy is the measure of the strength of the ionic bonding in a giant ionic lattice
• Lattice dissociation enthalpy is the enthalpy change when one mole of a solid ionic compound is completely dissociated into its gaseous ions under standard conditions (ENDOTHERMIC)
• Lattice formation enthalpy is enthalpy change when one mole of an ionic compound is formed from its gaseous ions under standard conditions (EXOTHERMIC)
• Enthalpy of solution is the enthalpy change when one mole of ionic solid is dissolved in water to infinite dilution so the ions no longer interact under standard conditions
• Enthalpy of hydration is the enthalpy change when one mole of gaseous ions is dissolved in water to form one mole of aqueous ions under standard conditions
• Enthalpy change of hydration is nearly always negative as water molecules have positive regions that attract negative ions
• calculating lattice dissociation enthalpy:

  ΔH1 = ΔHsol - ΔH2

  
• Hydration enthalpies decrease down a group due to the attractions being stronger with smaller ions and with ions with a greater charge
• Lattice dissociation increases with decreasing ionic radius and increasing charge due to the stronger attractions so more energy is needed for dissociation
• Entropy is the measure of disorder in a reaction which increases as the dispersal energy of a system increases
• Entropy increases as temperature increases because the particles gain energy and move faster and further apart
• Gases have the greatest entropy compared to solids and liquids
• ΔSsystemꝋ = ΣΔSproductsꝋ - ΣΔSreactantsꝋ
• ΔStotal = ΔSsystem + ΔSsurroundings
• ΔSsurroundings = -ΔH/T
• Ksp is the solubility product and indicates how much compound dissociates in water
• Ksp = [A+][B-]
• A conjugate acid is a species formed when a base accepts a proton
• A conjugate base if formed when an acid donates a proton
• A strong acid is an acid that completely dissociates into ions when in solution
• A weak acid is an acid that only slight dissociates into ions when in solution
• Weak acids and bases only slightly dissociate in solution to form an equilibirum mixutre which causes it to have an acid dissociation constant Ka
• Ka = [H+][A-]/[HA]
• pKa = -log10(Ka)
• pH = -log10[H+]
• Concentration of H+ ions is the same as the concnetration of an acid that fully dissociates
• Water slightly dissociates to from hydrogen and hydroxide ions and can be found by Kw
• Kw = [H+][OH-]
• Kw = 1.0 x 10^-14 at room temperature however as temp changes the value of Kw does also
• pKw = -log10(Kw)
• Buffers are a solution that can resist changes in pH when small volumes of acid or alkali are added
• Buffers can be formed by a weak acid and it's salt or an excess of weak acid and a strong alkali
• Buffer calculations:

  1. Acid + Base = find number of moles on each side, calculate concentrations at eqm, use Ka to find [H+] and therefore, pH
  2. Acid + Salt = find moles of salt, use Ka to find pH
• The greenhouse effect:

  1. radiation from atmosphere warming the planet
  2. planet then radiates IR outwards and greenhouse gases in troposphere absorb this and increase collisions due to vibration
  3. increasing collisions causes an over increase in temperature