Oceans Flashcards
What happens when a solute dissolves?
The solute and solvent bonds break, and new bonds are formed.
What determines if a substance dissolves in a solvent?
If the new bonds are weaker than the broken bonds, the substance won’t dissolve.
What are the types of solvents?
Polar (e.g., water) and non-polar (e.g., hexane).
Why do ionic substances dissolve in polar solvents?
The positive and negative ions form ion-dipole bonds with the solvent’s dipoles, breaking the ionic lattice.
What is solvation?
The process of ions being surrounded by solvent molecules.
What is hydration?
Solvation when the solvent is water.
Why do covalent substances dissolve in non-polar solvents?
Both have weak instantaneous dipole—induced dipole bonds, making them compatible.
Why don’t most covalent substances dissolve in polar solvents?
Hydrogen bonds in polar solvents (e.g., water) are stronger than the bonds formed with covalent substances.
What is lattice enthalpy (ΔLEHo)?
The enthalpy change when 1 mole of an ionic lattice forms from gaseous ions, always negative (exothermic).
What is hydration enthalpy (ΔhydHo)?
The enthalpy change when 1 mole of gaseous ions dissolve in water to form aqueous ions, always negative (exothermic).
What is the enthalpy change of solution (ΔsolHo)?
The enthalpy change when 1 mole of an ionic substance dissolves in enough solvent to form an infinite dilution.
How can the enthalpy change of solution be calculated?
Using a Hess cycle: ΔsolHo = −(lattice enthalpy) + sum of hydration enthalpies.
What factors affect lattice enthalpy?
Higher charge density increases electrostatic attraction, making lattice enthalpy more exothermic.
What factors affect hydration enthalpy?
Higher charge density makes water more attracted to ions, making hydration enthalpy more exothermic.
What is entropy (S)?
A measure of the number of possible arrangements of particles and energy quanta in a system.
What factors increase entropy?
Gases and liquids have higher entropy than solids, and higher energy or larger amounts of substances increase entropy.
How is total entropy change calculated?
ΔtotS = ΔsysS + ΔsurrS, where ΔsysS = Sproducts − Sreactants, and ΔsurrS = −ΔH/T.
What determines reaction feasibility?
A positive ΔtotS indicates feasibility, while a negative ΔtotS means the reaction isn’t feasible.
What is the solubility product (Ksp)?
The equilibrium constant for the dissociation of a sparingly soluble salt into its ions in a saturated solution.
How can a solubility product be determined experimentally?
Prepare a saturated solution, measure ion concentration using titration or colorimetry, and calculate Ksp.
What is the Brønsted-Lowry definition of acids and bases?
Acids are proton donors (release H+), and bases are proton acceptors.
What are conjugate acid-base pairs?
Pairs like HCl and Cl−, where one species donates or accepts a proton.
What are strong acids?
Acids that completely dissociate in water, e.g., HCl.
What are strong bases?
Bases that completely dissociate in water to form OH− ions.
What are weak acids?
Acids that only slightly dissociate in water, forming few H+ ions, e.g., CH3COOH.
How is Ka used for weak acids?
Ka = [H+]^2 / [HA], where [HA] is the concentration of the weak acid.
How is pKa calculated?
pKa = −log10Ka, and a smaller pKa indicates a stronger acid.
What is pH?
A measure of H+ concentration: pH = −log10[H+].
What is Kw
and how is it used?
What is a buffer solution?
A solution that resists pH changes when small amounts of acid or base are added.
How do acidic buffers work?
Made of a weak acid and its salt, they adjust equilibrium to resist pH changes when H+ or OH− is added.
What is the greenhouse effect?
Greenhouse gases absorb and re-emit IR radiation, trapping heat in the atmosphere.
What causes the enhanced greenhouse effect?
Increased greenhouse gases due to human activity, intensifying heat retention.
How do greenhouse gases trap heat?
They absorb IR, causing bond vibrations that transfer energy to other gas molecules, raising temperature.
