Buffers, Acids/Bases, and Organic vs Inorganic Chemistry — Vocabulary Flashcards

Vocabulary flashcards covering buffers, acids/bases, salts, polyatomic ions, and organic vs inorganic chemistry concepts discussed in the lecture.

pH

A measure of how acidic or basic a solution is, defined as pH = -log10[H+]; below 7 is acidic, above 7 is basic, and 7 is neutral at 25°C.

Hydronium ion

H3O+; the conjugate form of a proton in water, its concentration indicates acidity.

Hydroxide ion

OH-; the base component in water; higher [OH-] corresponds to a more basic solution.

Kw (ion-product of water)

Kw = [H+][OH-], the product of hydrogen and hydroxide ion concentrations (about 1.0×10^-14 at 25°C).

Acid

A substance that increases the hydronium (H3O+) concentration in solution; acids donate protons.

Base

A substance that increases hydroxide concentration or neutralizes hydronium; bases accept protons or donate OH- in reactions.

Neutral solution

A solution where [H+] = [OH-], pH ~7 at 25°C.

Buffer

A solution that resists changes in pH upon addition of small amounts of acid or base, typically containing a weak acid and its conjugate base or a weak base and its conjugate acid.

Buffer pair

A weak acid and its conjugate base or a weak base and its conjugate acid that work together to maintain pH.

Conjugate acid/base

Species that differ by one proton (H+); the conjugate base of an acid has one less H+, the conjugate acid has one more H+.

Weak acid

An acid that only partially dissociates in water; typically has a pKa between about 1 and 7; smaller pKa means stronger acid.

Strong acid

An acid that fully dissociates in water; examples include the seven strong acids (e.g., HCl, HNO3, H2SO4, HClO3, HClO4, HBr, HI).

pKa

The negative logarithm of the acid dissociation constant; lower pKa means stronger acid and greater tendency to donate protons.

Salt

An ionic compound formed from a metal cation and a nonmetal anion, often produced in acid-base reactions and used in buffers.

Polyatomic ion

An ion composed of two or more atoms (e.g., SO4^2-, HCO3^-, NO3^-); carries a net charge.

Organic compound

A compound that contains carbon and hydrogen (often with other elements); usually covalent bonding, lower melting/boiling points, and often less soluble in water.

Inorganic compound

A compound typically containing elements other than carbon and hydrogen; often ionic bonding with higher melting/boiling points and good water solubility.

Hydrocarbon

A compound consisting only of carbon and hydrogen; typically nonpolar and hydrophobic; includes alkanes, alkenes, etc.

Alkane

Saturated hydrocarbon with only single C–C and C–H bonds; general formula CnH2n+2; can rotate freely around single bonds.

Structural formula

A representation showing the actual bonds between atoms (single, double, triple) with lines.

Condensed structural formula

A shorthand representation of a molecule showing connectivity (e.g., CH3-CH2-CH3) without drawing all bonds.

Skeletal (line-angle) formula

A minimalist drawing where vertices/endpoints represent carbon atoms and bonds are implied; commonly used for hydrocarbons.

Terminal carbon

A carbon atom at the end of a carbon chain.

HONC rule (valence rule)

Hydrogen = 1 bond, Oxygen = 2 bonds, Nitrogen = 3 bonds, Carbon = 4 bonds; guides counting bonds in organic molecules.

Solubility

The ability of a substance to dissolve in a solvent; soluble means it mixes evenly, insoluble means layers or precipitates form.

Seven strong acids (examples)

Acids that fully dissociate in water; examples include HCl, HNO3, H2SO4, HClO3, HClO4, HBr, HI.

Alcohols and conjugate bases

Alcohols (R–OH) can act as very weak acids; their conjugate bases are alkoxides/alkoxides (RO-); example: ethanol (CH3CH2OH) and ethoxide (CH3CH2O-).