L1 - Acid-base and mineral solubility Flashcards
what is the law of mass action
states that reactions reach equilibrium when the rate of the forward reaction equals the rate of the backward reaction
what is the equilibrium constant (K) in a chemical reaction
expresses the ratio of concentrations (or activities) of products to reactants for a chemical reaction at equilibrium
what is the formula for the forward reaction rate in a chemical reaction
the forward reaction rate is V t=kt [A][B], where 𝑘𝑡 is the rate constant, and [𝐴] and
[𝐵] are the molar concentrations of the reactants.
what is the formula for the backward reaction rate in a chemical reaction
The backward reaction rate is Vb = kb [C][D]
where kb is the rate constant, and [C] and [D] are the molar concentrations of the product
define acid and base dissociation
Acid dissociation: an acid dissociates in water to release H+ ions (protons) lowering the pH
Base Dissociation: a base dissociates in water to release OH- ions (hydroxide ions), raising the pH
what is the dissociation constant for acids and bases
Ka is the dissociation constant for acids
Kb is the dissociation constant for bases
what is the difference between strong and weak acids/ bases
Strong acids/bases: dissociate almost completely in water e.g. HCl
Weak acids/bases: only partially dissociate in water e.g. CH3COOH- acetic acid
how is the strength of an acid or base measured?
pH = measures the acidity or basicity of a solution
pKa = measures the dissociation strength of an acid (pKb for bases)
what is a buffer
a solution that resists changes in pH when an acid or base is added, typically by consuming H+ or OH- ions
give an example of a common buffer in nature
Seawater - containing bicarbonate (HC)3-) and calcium carbonate (CaCO3) which maintain pH around 7.9
what is the relationship between CaCO3 and buffering capacity in seawater
excess H+ ions in seawater can be buffered by the dissolution of CaCO3-
CaCO₃(s)+H⁺⇋Ca²⁺+HCO₃⁻.
what are oxidation-reduction (redox) reactions
involve the transfer of e-, where oxidation is loss of e- and reduction is the gain of e-
what are the roles of oxidizing and reducing agents in redox reactions
oxidizing agent: accepts e- (reduced)
reducing agent: donates e- (oxidized)
what is Eh and how is it related to redox reactions
Eh measures the redox potential of a solution relative to the standard hydrogen electrode (SHE) indicating its tendency to accept or donate e-
define pE in the context of redox reactions
pE is a meaure of electron activity, similar to how pH measure proton activity
define as pE=−log[e−]
what does a low pE value indicate about a solution
a low PE value = solution is reducing, it has a source of e-
what is the Nerst equation used for in redox reactions?
The nerst equation is used to determine the speciation of metals in solution based on e- activity and redox potential
What are pourbaix diagrams
polts of Eh or pE vs pH, used to describe the chemical behaviour of species in natural waters and soils
How does oxidation state affect the mobility and toxicity of elements in the environment
the oxidation state of an element influences its chemical speciation, mobility and toxicity in the environment
what is the OIL RIG acronym in redox reactions?
OIL = oxidation is loss of e-
RIG = reduction of e-
