AP®︎ Chemistry: Unit 4 Flashcards

A change in form or properties that does not alter a substance's chemical composition.

Possible signs include heat or light, gas formation, precipitate formation, and color change.

Common physical changes where state or arrangement changes, but chemical identity stays the same.

Synthesis: A + B → AB; decomposition: AB → A + B; single replacement: AB + C → AC + B; double replacement: AB + CD → AD + CB; combustion: hydrocarbon + O2 → CO2 + H2O.

A process in which atoms rearrange to form new substances with different compositions.

A symbolic representation of a reaction showing reactants, products, formulas, and relative amounts.

A mixture in which a substance is dissolved in water and written with the phase symbol (aq).

When dissolved in water, soluble ionic compounds separate into their individual aqueous ions.

A reaction written with compounds shown as intact formulas rather than separated aqueous ions.

A reaction written with all strong electrolytes in solution separated into their aqueous ions.

Dissociate soluble aqueous ionic compounds; do not split solids, liquids, gases, or weak electrolytes.

Balance the reaction, dissociate soluble aqueous species, cancel spectator ions, and keep phases shown.

A symbolic representation of a phase change or dissolution without forming new substances.

An aqueous reaction that forms an insoluble solid product that separates from solution.

A reaction in aqueous solution that forms an insoluble solid called a precipitate, which separates from solution.

An equation showing only the species that actually change in a reaction, with spectator ions omitted.

Ions present in solution that appear unchanged on both sides of the ionic equation and do not participate in the overall chemical change.

Coefficients change particle amounts; subscripts change a substance's identity and composition.

Symbols like s, l, g, and aq show each substance's physical state in a reaction.

Atoms are single spheres, molecules are bonded groups, and ions carry charges.

The lowest whole-number ratio of ions in an ionic compound, not a discrete molecule.

Bonded atoms should be connected, while separate ions or unbonded particles should be drawn apart.

A particle-level drawing made from a balanced equation showing the correct particles before and after.

Physical changes keep particle identity the same, while chemical changes rearrange atoms into new substances.

A symbolic reaction written with whole-number coefficients so that each element has the same number of atoms on both sides, and total charge is balanced when applicable.

Matter is neither created nor destroyed in a chemical reaction, so each element has the same number of atoms before and after, making reactant and product amounts quantitatively related.

Bonds within a substance, such as covalent or ionic bonds between atoms or ions.

Attractions between separate particles, including hydrogen bonding, dipole forces, and dispersion forces.

A physical change between states of matter caused by changing intermolecular attractions.

Reactants must break existing bonds and form new ones to rearrange into products.

An ambiguous process where ionic attractions break and ion-dipole interactions form in solution.

Attractions between ions and polar molecules, such as dissolved ions and water molecules.

Many can be undone because the substance's chemical identity remains unchanged.

Chemical changes alter intramolecular bonds, while physical changes mainly alter intermolecular attractions.

Whole-number values in an equation that show relative mole amounts of substances.

A conversion factor from equation coefficients relating moles of one substance to another.

Convert grams to moles, use a mole ratio, then convert back to grams.

Use Avogadro's number and mole ratios to convert between numbers of particles.

Use 22.4 L/mol with mole ratios to relate gas volume and chemical amounts.

Use PV = nRT to find gas moles, then apply mole ratios.

Use molarity to find moles in solution, then apply mole ratios.

Set up conversion factors so unwanted units cancel and the target unit remains.

Using balanced equations and mole ratios to calculate reactant and product amounts.

An experimental method that determines an unknown concentration using a reacting solution of known concentration.

The solution of known concentration added to react completely with the substance being measured.

The solution of unknown concentration whose amount or concentration is determined in the procedure.

A substance that changes color over a certain pH range to signal the endpoint.

A titration in which an acid and base react quantitatively to determine an unknown concentration.

A graph of solution pH versus volume of titrant added during the procedure.

The point of greatest slope change on the curve, corresponding to the equivalence point.

One is stoichiometric completion, while the other is the observable change used to detect it.

At equivalence, use mole ratios and measured volumes to relate titrant and analyte amounts.

A reaction in which one species transfers one or more protons to another.

A redox reaction in which a substance reacts with O2; hydrocarbons completely form CO2 and H2O.

All sodium, potassium, ammonium, and nitrate salts are soluble in water.

An acid donates H+; a base accepts H+ in a proton-transfer reaction.

Strong acids have weak conjugate bases, and strong bases have weak conjugate acids.

Proton transfer favors formation of the weaker acid and weaker base.

A species that can either donate a proton or accept a proton.

In aqueous solution, H2O can accept H+ to form H3O+ or donate H+ to form OH-.

Two species that differ by one proton; the acid has one more H+.

In water, acids donate H+ to H2O and bases accept H+ from H2O.

An equation showing either the oxidation part or the reduction part of a redox reaction.

In peroxides oxygen is -1, in metal hydrides hydrogen is -1, and halogens besides fluorine can vary.

Loss of electrons is oxidation, gain is reduction; oxidizers are reduced and reducers are oxidized.

Balance atoms, then charge with electrons; in basic solution, neutralize H+ using OH-.

Add electrons to balance charge, equalize electron transfer, combine half-reactions, and verify atoms and charge.

A reaction involving electron transfer in which one species is oxidized and another is reduced, causing changes in oxidation numbers.

The assigned or hypothetical charge of an atom in a compound or ion, used to track electron transfer and identify oxidation and reduction in reactions.

Rules for assigning oxidation numbers: free elements are 0; monatomic ions equal their charge; oxygen is usually -2; hydrogen is usually +1; fluorine is -1; and the sum of oxidation numbers equals the overall charge of the species.