Chemistry Quiz Reviewer: Acids & Bases, Buffers, and Chemical Equilibrium

A 70-card fill-in-the-blank practice set covering acid-base theories, pH calculations, neutralization, buffers, and chemical equilibrium principles.

According to Arrhenius theory, an acid is a substance that increases the concentration of __________ in aqueous solution.

$H^+$ (or $H_3O^+$)

Under the Arrhenius definition, a base increases the concentration of __________ when dissolved in water.

$$OH^-$$

The Arrhenius definition is narrower than other acid–base theories because it is tied strictly to __________ solutions.

aqueous

In Brønsted–Lowry theory, an acid is defined as a proton ($H^+$) __________.

donor

In Brønsted–Lowry theory, a base is defined as a proton ($H^+$) __________.

acceptor

A conjugate acid–base pair consists of two species that differ by __________ proton.

one

According to Lewis theory, an acid is defined as an __________ pair acceptor.

electron

According to Lewis theory, a base is defined as an __________ pair donor.

electron

Unlike Brønsted–Lowry acid–base reactions which always involve proton transfer, Lewis acid–base reactions need not involve __________ at all.

$$H^+$$

The mathematical formula defining $pH$ is __________ .

$$-\\log_{10}([H_3O^+])$$

To calculate hydronium concentration from $pH$, the relationship used is $[H_3O^+] =$ __________ .

$$10^{-pH}\\,\\text{mol/L}$$

At 25\\,^\\circ\\text{C}, the sum of $pH$ and $pOH$ for an aqueous solution equals __________ .

$$14$$

In neutral water at 25\\,^\\circ\\text{C}, the concentrations of hydronium and hydroxide are equal to __________ .

$$1 \\times 10^{-7}\\,\\text{M}$$

At 25\\,^\\circ\\text{C}, solutions with a $pH$ between $0$ and $6.9$ are classified as __________ .

acidic

At 25\\,^\\circ\\text{C}, solutions with a $pH$ between $7.1$ and $14$ are classified as __________ .

basic / alkaline

Under the tenfold rule of the logarithmic $pH$ scale, a change of $1\\,pH$ unit corresponds to a __________ change in hydronium concentration.

tenfold

A solution with a $pH$ of $3$ has __________ times the hydronium concentration of a solution with a $pH$ of $5$.

$$100$$

The familiar $0$ to $14$ $pH$ scale is a classroom model, meaning sufficiently concentrated solutions can have $pH$ values __________ .

outside this range

The separation of an ionic compound into its pre-existing ions when dissolved is known as __________ .

dissociation

The process of forming ions from neutral molecules, often by reaction with water, is known as __________ .

ionization

The net ionic equation for many aqueous strong acid–strong base neutralizations is __________ .

$$H_3O^+ + OH^- \\rightarrow 2H_2O$$

Neutralization does not always produce a solution with a $pH$ of $7$ because the final $pH$ depends on acid/base strengths, amounts, and __________ .

conditions

A substance that is able to donate or accept a proton ($H^+$) depending on the reaction partner is called __________ .

amphiprotic

Three common examples of amphiprotic substances mentioned in the reviewer are water ($H_2O$), dihydrogen phosphate ($H_2PO_4^-$), and __________ .

hydrogen carbonate ($HCO_3^-$)

While amphiprotic refers specifically to donating and accepting protons, the broader term __________ means able to behave as either an acid or a base under the relevant theory.

amphoteric

Acid __________ describes how extensively an acid ionizes, whereas concentration describes how much solute is present per volume.

strength

A solution with a relatively small amount of solute per volume of solution is described as __________ .

dilute

A solution with a relatively large amount of solute per volume of solution is described as __________ .

concentrated

An acid or base that ionizes or dissociates essentially completely in water under ordinary introductory conditions is classified as __________ .

strong

An acid or base that only partially ionizes or reacts in water to form an equilibrium mixture is classified as __________ .

weak

Molarity ($M$) is calculated as moles of solute divided by __________ .

liters of solution

A quantitative procedure used to determine an unknown concentration by gradually adding a solution of known concentration is called __________ .

acid–base titration

In a titration, the solution of known concentration delivered from a burette is called the __________ .

titrant

In a titration, the solution being analyzed whose concentration may be unknown is called the __________ .

analyte

A substance that changes color over a characteristic $pH$ range during a titration is called an __________ .

indicator

The point in a titration where stoichiometrically equivalent amounts of acid and base have reacted is the __________ .

equivalence point

The observed signal, such as an indicator color change, used to stop a titration is known as the __________ .

endpoint

A solution whose concentration is accurately known is referred to as a __________ .

standard solution

For a titration involving a $1:1$ stoichiometric reaction, the relationship between molarities and volumes is __________ .

$$M_1V_1 = M_2V_2$$

A solution that resists large $pH$ changes when small amounts of acid or base are added is called a __________ .

buffer solution

A buffer solution commonly consists of a weak acid and its __________ (or a weak base and its conjugate acid).

conjugate base

In a buffer system, added $H^+$ is consumed by the __________, while added $OH^-$ reacts with the weak acid.

conjugate base

In human blood, the primary buffer system that helps maintain $pH$ within a narrow range is the __________ system.

carbonic acid–bicarbonate ($H_2CO_3/HCO_3^-$)

In maintaining blood $pH$, the lungs regulate $CO_2$, while the kidneys help regulate __________ and acid excretion.

bicarbonate

Inside cells, phosphate and __________ buffers help stabilize $pH$ for cellular processes and enzyme activity.

protein-based

Aquatic ecosystems with low __________ are particularly vulnerable to acidification from acid rain.

alkalinity/buffering capacity

The amount of added strong acid or strong base required to change a buffer's $pH$ by a specified amount is known as the __________ .

buffer capacity

Buffer capacity is usually greatest when the weak acid and its conjugate base are present in __________ amounts.

comparable

For a weak acid/conjugate-base buffer, the effective buffer range is commonly approximated as __________ .

$$pK_a \\pm 1$$

While buffer range describes the $pH$ interval where a buffer is effective, buffer __________ describes how much acid or base it can absorb before $pH$ changes substantially.

capacity

Chemical equilibrium is a dynamic state in a reversible reaction where forward and reverse reaction __________ are equal.

rates

At chemical equilibrium in a closed system, the concentrations of reactants and products remain constant, but they are not necessarily __________ .

equal

Equilibrium is described as dynamic because both forward and reverse reactions continue at equal rates, meaning reactions have not __________ .

stopped

A chemical equilibrium where all reacting species exist in the same phase is called a __________ equilibrium.

homogeneous

A chemical equilibrium where reacting species exist in different phases is called a __________ equilibrium.

heterogeneous

The relative amounts of reactants and products present at equilibrium define the __________ .

equilibrium position

In writing standard equilibrium constant expressions ($K_c$), pure solids and pure liquids are omitted because their activities are effectively __________ .

constant

The equilibrium constant written specifically using the partial pressures of gaseous species is designated as __________ .

$$K_p$$

The equation relating $K_p$ and $K_c$ for gaseous equilibria is __________ .

$$K_p = K_c(RT)^{\\Delta n_{\\text{gas}}}$$

In the expression $K_p = K_c(RT)^{\\Delta n_{\\text{gas}}}$, the term $\Delta n_{\\text{gas}}$ represents total gaseous product coefficients minus __________ .

total gaseous reactant coefficients

When the equilibrium constant $K \\gg 1$, the equilibrium mixture favors the __________ .

products

When the equilibrium constant $K \\ll 1$, the equilibrium mixture favors the __________ .

reactants

For a given chemical reaction as written, the only variable that alters the numerical value of $K$ is __________ .

temperature

The expression that has the same form as $K$ but uses current, non-equilibrium concentrations or partial pressures is called the __________ .

reaction quotient ($Q$)

If a reaction mixture has $Q < K$, the system will shift in the __________ direction to reach equilibrium.

forward (toward products)

If a reaction mixture has $Q > K$, the system will shift in the __________ direction to reach equilibrium.

reverse (toward reactants)

According to Le Châtelier's principle, when a system at equilibrium is disturbed, it shifts to __________ the disturbance.

partially counteract

Increasing pressure by decreasing volume in a gaseous equilibrium causes the system to shift toward the side with __________ .

fewer moles of gas

Adding an inert gas to a gaseous equilibrium at constant volume causes __________ in the equilibrium position.

no shift

Adding a catalyst to a reaction at equilibrium increases the rates of both forward and reverse reactions, but does not alter the equilibrium composition or the value of __________ .

$$K$$