Chem 1 Flashcards
Ka = [H3O+][A-] / [HA]. - the smaller the value of Ka, the weaker the acid. Kb = [B+][OH-] / [BOH] - the smaller the value of Kb, the weaker the base. Ka * Kb = Kw = 10^-14
How do you calculate the acid dissociation constant, Ka? How does the strength of the acid compare the constant? What about the base dissociation constant, Kb? How are they related?
pH = -log[H+] = log(1/[H+]) pOH = -log[OH-] = log(1/[OH]) pH + pOH = 14
How do you calculate the pH and pOH? How are they related to the water dissociation constant?
The equivalence point, which is at pH 7 for a strong acid/strong base titration, < 7 strong acid/weak base titration and >7 for weak acid/strong base titrations
On a titration curve, what does the point of greatest slope represent?
arrhenius acid- species that dissocates in water to produce a hydrogen ion. arrhenius base- species that dissociates in water to produce a hydroxide ion. Bronsted-Lowry acid- species that donates hydroen ions Bronsted-Lowry base- species that accepts hydrogen ions Lewis acid- species that accepts an electron pair Lewis base- species that donates an electron pair
What are the arrhenius definitions for acids and bases? Bronsted-Lowry definitions? Lewis definitions?
1) strong acid and strong base –> neutral pH 2) strong acid and weak base –> acidic pH 3) weak acid and strong base –> basic pH 4) weak acid and weak base –> depends on the relative strengths of the reactants.
What are the four types of neutralization reactions and what is the resultant pH of each?
Acids - HCl, HBr, HI, H2SO4, HNO3, HClO4 Bases - NaOH, KOH, and other soluble hydroxides of group IA and IIAmetals.
What are the strong acids and bases that are commonly tested on the MCAT?
The buffer region, which correponds to the pKa or pKb, depending on the species. It must be a polyvalent acid or base. Each region is a different buffer region corresponding to the pKa or pKb for the specific proton.
What does the portion of a titration curve w/ the smallest slope represent? What if there are multiple regions of very small slopes?
A buffer solution consists of a misture of a weak acid and its salt (which consists of its conjugate base and a cation) or a mixture of a weak base and its salt (which consists of its conjugate acid and an anion). Buffer solutions resist changes in pH when small amounts of strong acid or base are added.
What is a buffer solution?
A neutralization reaction is one in which an acid and base react to form a salt and often (but not always) water. Hydrolysis is the reverse reaction, salt ions react w/ water to give back the acid or base.
What is a neutralization reaction? What about hydrolysis?
One that acts as a base in the presence of an acid and acts as an acid in the presence of a base.
What is an amphoteric species?
Equivalence point is when theh number of acid equivalents present in the original solution equals the number of base equivalents added, or vise vera. The pH does NOT have to be neutral (strong base and weak acid, for example) End point is the point at which the indicator changes color.
What is the equivalence point of an acid/base titration What is the end point?
The gram equivalent weight is the mass of a compound that produces one equivalent (one mole of charge).
What is the equivalent weight of a compound?
pH = pKa + log [conjugate base] / [weak acid], for weak acid buffer solution OR pOH = pKb + log [conjugate acid] / [weak base], for weak base buffer solution It is used to estimate the pH or pOH of a soltion in the buffer region where the concentrations of the species and its conjugate base are present in approximately equal concentrations. If you double the concentrations of the buffer components, the buffer solution has a 2x buffering capacity.
What is the Henderson-Hasselbalch equation and what is it used for? What is the effect of changing the concentrations in the equation?
The equilibrium expression for the auto-ionization of water. It is an equilibrium constant and cannot be changed unless the temperature of water is changed. Kw = [H3O+][OH-] = 10^-14 at 25 degrees celcius.
What is the water dissociation constant, Kw?
