ch 10 Flashcards
what is the process of hydration
incorporation of water molecules into or between molecules or mineral crystal lattice without a chemcial reaction
what is the process of acid base
exchange of a proton
what is the process of precipitation/dissolution
formation or dissolution of a solid, usually involves hydration
what is the process of adsorption/desorption
chemical interaction between chemical and surface
what is the process of complexation
formation of an ion complex
what is the process of partitioning
movement of a molecule from one phase into another
what is carbonic acid
H2CO3
what is the product of carbonic acid dissociating
HCO3-
what is the second step of carbonic acid dissocation produce
CO32-
how do the two K values for carbonic acid dissocation change with temperature and salinity
strongly increase with temperature and weakely decrease with salinity
how can we estimate the distribution of all the forms of carbonic acid at differnt pHs
using pH and the two Kas
what are the trends of common weak acids and bases in fresh versus salt water
seawater is inriched in carbonate forms indicating that processes in the ocean remove the other acids
freshwater is rich in silicate and carbonic forms
what are the trends of common weak acids and bases in fsurface versus deep water
surface is lower in acids because they are removed in the surfcae
higher in deep water due ot thermohaline circulation, more time for things to accumulate due to respiration
more time for shells to dissolve and break down and the water is more acidic
what happens when a strong acid is dissolved
it deprotonates entirelywh
what happnes when a weak acid dissolves
only some of the acid wiill dissolve leading to equilibrium arrows
what do weak acids act as
buffers to stabilize the pH in the ocean
a quick drop in pH indicates that all the product converted tot he weak acid form so now all other H+ goes towards changing the ph
Most polyprotic acids and bases are
weak
what is an important diprotic acid/base system in the ocean
carbonate system
keeps the ocean between 7.9 and 8.4 pH
under what conditions does the second step of the carbonate system happen
in higher ph
what is a complex
a substance formed by the union of simpler substances held together by chemical forces
dependent on properties of particular atomic structures rather than physical ones like chemical attraction
what are the metals in complexes
lewis acids- accept electron donating ligands which are lewis bases
what is a bronsted lowry acid
gives off one or more H+
most transition metal can bind _ ligands
up to 6
what is the equilibrium coefficient for complexatino
formation constant
how are ligands categorized
by the number of binding sites that can form
ex. tridentate can form four metal lgand bonds
what is a chelating ligand
a lingand that binds to a metal through multiple atoms
how does the formation constant differ betwen chelating and monodentate ligands
it is higher for chelating ligands becaues of the chelate effect
what is the chelate effect
chelating ligands are thermodynamically more stable than monodentate ligands
charge and complxe formation of DOM
organic molecules from DOM are typically negatively charged forming complexes with metals
what are the functional groups that form complexse with metals from DOM
R-COO-
R-S-
R2-NH
R-NH2
these multiple functional groups allow these ligands to chelate leading to a higher Kf
competing formation
since in a real system tehre are many ligand that can interact with a metal, theere will be competition amongst ligands to form complexes allowing the ligands with the best Kf and concentration to win
free ion complexatino is improtantt for
trace metals like
Mn
Co
Ni
Ag
Cd
what are the most common compelxing agents for trace metals
OH-
Cl-
SO42-
CO32-
DOM
what complexation agent is imporatnt in anoxic enviroments for trace metals
SO3-
organic complexation is important for
Cu
Zn
Fe
Pb
Hg
speciation effects of what are important
of the metal beacuse the conc of ligand greatly exceeds the metal
what are the biological impacts of trace metal complexation
compelxed copper is less available and less toxic
Hg more available more toxic
Fe more available- good thing for algae
what is the importance of irom complexes
irion is a limiting nutreint in ocean waters
iron fertilization- bc iron is rquired for the use of other elements
depends on which form the iron is supplied in- different organisms benifit differently
complexation is an effcetive way to dissolve iron and make it available - otherwise particulate iron if not quickly dissolved is lost for surface waters
siderophores
small ligands secreted by bact to bring iron across membranes
l
how is light involved in iron complexation
it brings iron from between the reduced and oxidized form
weather and its effcet on iron
cold weather increases erosion of sant and silicates and iron are released
high iron stimulates growth of algae leads to decreased Co2 because they remove it from air and this leads to colder temperatures
