CHM 30 Chapter 4: Reactions in Aqueous Solutions

Vocabulary flashcards covering key terms from CHM 30 Chapter 4 notes.

Solution

A homogeneous mixture of two or more substances.

Solvent

The substance with the greatest number of moles in a solution; the dissolving medium.

Solute

The substance(s) dissolved in the solvent; the rest of the components.

Aqueous solution

A solution in which water is the solvent.

Dissociate

To break down into component ions in an aqueous solution.

Hydration shell

Water molecules arranged around dissolved ions.

Molarity (M)

Moles of solute per liter of solution; unit of mol/L.

Concentration

Amount of solute in a given amount of solvent or solution.

Brackets notation

[X] or [X+] denotes the concentration of species (e.g., [Ag+] = 0.1 M).

Stock solution

A concentrated solution used to prepare solutions of lower concentration.

Dilution

Process of lowering concentration by adding solvent; moles before = moles after.

M1V1 = M2V2

Dilution equation used to relate initial and final concentrations and volumes.

Moles conserved in dilution

During dilution, the number of moles remains the same even though volume changes.

Beer's Law

A = ε b c; relationship between absorbance, molar absorptivity, path length, and concentration.

Absorbance

Measure of how much light a sample absorbs.

Molar absorptivity (ε)

Constant that describes how strongly a substance absorbs light at a given wavelength.

Path length (b)

The distance light travels through the sample (cuvette width).

Electrolyte

Substance that increases conductivity when dissolved in water.

Strong electrolyte

Completely ionizes in solution (e.g., NaCl, HCl, HNO3; strong bases).

Weak electrolyte

Partially ionizes in solution (e.g., weak acids and bases; NH3).

Nonelectrolyte

Substance that does not increase conductivity when dissolved (e.g., sugars, alcohols).

Bronsted-Lowry acid

A substance that donates a proton (H+).

Bronsted-Lowry base

A substance that accepts a proton (H+).

Hydronium ion (H3O+)

The protonated water ion formed when acids donate H+ in water.

Monoprotic

An acid with one acidic hydrogen per molecule.

Diprotic

An acid with two acidic hydrogens per molecule.

Triprotic

An acid with three acidic hydrogens per molecule.

Amphiprotic

A species that can act as both an acid and a base.

Neutralization

An acid-base reaction that forms water and a salt.

Salt

Ionic compound formed from the reaction of an acid and a base.

Spectator ion

Ion that does not participate in the reaction; appears unchanged in net ionic equations.

Molecular equation

Equation showing all species in their complete formulas, no ions.

Complete ionic equation

All strong electrolytes are written as their ions; other species are shown in full.

Net ionic equation

Equation that omits spectator ions to show only species that change.

Titration

Analytical method to determine a solute's concentration by reacting it with a standard solution.

Standard solution (titrant)

A solution of known concentration used to titrate a sample.

Equivalence point

The point at which the titrant has completely reacted with the analyte (stoichiometric amount).

End point

Visual signal (often a color change) indicating the endpoint of titration.

Indicator

Substance that changes color with pH to signal the end point.

Precipitation reaction

A reaction where an insoluble solid forms when two solutions are mixed.

Solubility rules

Guidelines predicting whether compounds are soluble or insoluble in water.

Insoluble

A substance that does not dissolve in water under the given conditions.

Redox

Oxidation-reduction reactions; transfer of electrons between species.

Oxidation number

A formal charge assigned to elements to track electron transfer.

Oxidation

Increase in oxidation number; loss of electrons.

Reduction

Decrease in oxidation number; gain of electrons.

Oxidizing agent

Substance that is reduced and causes oxidation of another species.

Reducing agent

Substance that is oxidized and causes reduction of another species.

Half-reaction

One of the two component reactions (oxidation or reduction) in a redox process.

Acidic balancing steps

In acidic solution, balance O with H2O, balance H with H+, balance charge with electrons.

Basic balancing steps

In basic solution, balance O with H2O, balance H with OH-, balance charge with electrons.