MCAT CHEM/PHYS: Acid-Base Chemistry Flashcards

Question 1

Define Bronsted-Lowry Acid.

Accepted Answer

Any species capable of transferring a hydrogen ion to another substance during a reaction, a definition that applies whether or not the reaction happens in water.

Question 2

Define Bronsted-Lowry Base.

Accepted Answer

Any species that accepts a hydrogen ion in a reaction, using an available lone pair to bond the incoming proton.

Question 3

Define Arrhenius Acid.

Accepted Answer

A substance that, when dissolved in water, raises the concentration of hydrogen ions in the solution, the earliest and narrowest of the three classical acid definitions.

Question 4

Define Lewis Base.

Accepted Answer

A species that donates an electron pair to form a new covalent bond with another atom or ion, the broadest of the three acid-base models because no proton needs to move at all.

Question 5

Define Conjugate Acid.

Accepted Answer

The species left behind once a base has accepted a hydrogen ion, meaning every base has a matching conjugate acid one proton heavier than itself.

Question 6

Define Acid Dissociation Constant (Ka).

Accepted Answer

The equilibrium constant for a weak acid ionizing in water, calculated as the concentration of products over reactants at equilibrium, and used to quantify exactly how far that ionization proceeds.

Question 7

Define Base Dissociation Constant (Kb).

Accepted Answer

The equilibrium constant describing how completely a weak base picks up a proton from water, playing the same role for bases that Ka plays for acids.

Question 8

Define Autoionization of Water.

Accepted Answer

The reaction of water molecules with each other to form small equal amounts of hydronium and hydroxide ions, governed by the constant Kw, which equals 1.0 x 10^-14 at 25 degrees Celsius.

Question 9

What is pOH?

Accepted Answer

The negative base-ten logarithm of hydroxide ion concentration, related to pH by the fixed relationship pH plus pOH equals fourteen at 25 degrees Celsius.

Question 10

Define Hydronium Ion (H3O+).

Accepted Answer

The species that actually forms when a proton attaches to a water molecule, representing what free H+ really looks like in aqueous solution rather than an isolated bare proton.

Question 11

What is Titration?

Accepted Answer

A laboratory technique that measures out a solution of precisely known concentration into a sample of unknown concentration until the reaction between them is complete, letting the unknown be calculated from the volume used.

Question 12

What is Titrant?

Accepted Answer

The solution of precisely known concentration that is added, usually from a buret, into the sample being tested during a titration.

Question 13

What is Analyte?

Accepted Answer

The solution whose concentration is unknown and is being determined by reacting it with a titrant of known concentration.

Question 14

Define Strong Acid.

Accepted Answer

An acid that ionizes essentially completely in water, so at equilibrium almost no intact acid molecules remain and the reaction is treated as going to completion.

Question 15

Define Weak Acid.

Accepted Answer

An acid that ionizes only partially in water, establishing a true equilibrium between its molecular and ionized forms rather than reacting to completion.

Question 16

Define Buffer Capacity.

Accepted Answer

The quantity of added acid or base a buffer solution can absorb before its pH begins to shift noticeably, largest when the weak acid and conjugate base are present in roughly equal amounts.

Question 17

Define Common-Ion Effect.

Accepted Answer

The suppression of a weak electrolyte's ionization that occurs when a second, soluble compound sharing one of its ions is added to the same solution, pushing the equilibrium back toward the un-ionized form.

Question 18

Define Neutralization Reaction.

Accepted Answer

A reaction in which an acid and a base combine to produce water and a salt, generally releasing heat as the products form.

Question 19

Define Salt Hydrolysis.

Accepted Answer

The reaction of an ion released by a dissolved salt with water, producing extra hydrogen or hydroxide ions and shifting the solution's pH away from neutral.

Question 20

Define Titration Curve.

Accepted Answer

A plot of a solution's pH against the volume of titrant added during a titration, whose shape, inflection points, and flat regions reveal the acid or base's identity, strength, and pKa.

Question 21

Define Buffer Region.

Accepted Answer

The flat, gently sloping stretch of a titration curve where added acid or base changes the pH only slightly, occurring where meaningful amounts of both the weak acid and its conjugate base coexist.

Question 22

Define Titration Indicator.

Accepted Answer

A weak acid or base dye whose two forms have different colors, chosen so its color-change range overlaps the point where the titration reaction is essentially complete.

Question 23

Define Leveling Effect.

Accepted Answer

The phenomenon by which every strong acid appears equally strong once dissolved in a given solvent, because each one ionizes completely and the solvent's own conjugate base sets the effective acidity ceiling.

Question 24

Define Isoelectric Point (pI).

Accepted Answer

The specific pH at which an amino acid or protein carries no net electric charge overall, because its positively and negatively charged groups exactly balance.

Question 25

Define Respiratory Acidosis.

Accepted Answer

A fall in blood pH that results when breathing is too slow or shallow to clear carbon dioxide, letting carbonic acid build up faster than the body can compensate.

Question 26

Define Respiratory Alkalosis.

Accepted Answer

A rise in blood pH caused by breathing too fast or too deeply, which clears carbon dioxide out of the blood faster than the body produces it.

Question 27

Define Metabolic Acidosis.

Accepted Answer

A fall in blood pH driven by a cause outside the lungs, such as excess acid production or loss of bicarbonate, rather than by a breathing problem.

Question 28

Define Metabolic Alkalosis.

Accepted Answer

A rise in blood pH driven by a cause outside the lungs, such as prolonged loss of stomach acid, rather than by a change in breathing.

Question 29

Define Anion Gap.

Accepted Answer

A calculated value found by subtracting the sum of measured blood anions from measured cations, used to narrow down which process is behind a case of metabolic acidosis.

Question 30

Define Amphoteric Solvent.

Accepted Answer

A solvent molecule that, like water, can itself act as either a proton donor or a proton acceptor depending on what it reacts with, which is why water can be both an acid and a base in different reactions.