Oceans Flashcards
Describe how an ionic lattice is formed.
Cations attract anions. There is a series of strongly held attractions and repulsions.
Describe lattice enthalpy.
Assumed ions are in the gaseous state.
Endothermic process.
Enthalpy change when one mole of a solid is formed by the joining of separate ions.
Dissolving lattices are minus lattice enthalpy.
Define enthalpy change of hydration.
Formation of a solution of ions from one mole of gaseous ions.
Always negative.
Define enthalpy change of solvation.
Formation of a solution of ions from one mole of gaseous ions, referring to polar solvents, not water.
Define enthalpy change of solution.
One mole of a solute dissolves to form a very dilute solution.
ΔsolH = ΔHydH(cation)+ ΔHydH(anion) - ΔLEH.
Describe the ocean’s role in climate change.
Absorption of CO2. Phytoplankton transports CO2 to the deep oceans. Dissolves into hydrogen carbonate and H+ ions.
Describe radiation.
Hot objects emit electromagnetic radiation. Sun emits UV, visible and IR. The earth radiates IR. Carbon dioxide and methane absorb IR. Absorption of IR increases vibrational energy, some is re-emitted. Water vapour is the most abundant greenhouse gas. The IR window refes to the wavelength not absorbed by water vapour.
How do acids work as conjugate bases?
The acid may take back the proton. If a stronger acid is added, the weaker acid will take the proton.
A weak acid is less likely to dissociate completely in water.
How does water act as an acid and a base?
HCl + H2O > H30+ + Cl-, acting as a base.
H2O + NH3 > OH- + NH4+, acting as an acid.
Define a buffer solution.
Resists changes in pH. Usually made from either: a weak acid and one of its salts, or a weak base and one of its salts.
What are the assumptions when using a buffer solution?
All A- ions come from the salt. Almost all HA in buffer remains unchanged.
How does a buffer react to the addition of H+ ions?
Some A- react with these H+ ions to form HA and water.
How does a buffer react to the addition of OH- ions?
H+ ions are removed but reformed from HA.
Define entropy.
A measure of the amount of disorder in a system.
What factors change entropy?
More molecules being made, exothermic reactions, change in state.
