chem lecture 4 ai notes

Neutralization Reaction

A chemical reaction between an acid and a base that produces a salt and often water.

Net Ionic Equation

The simplified chemical equation that shows only the species that actually change during a reaction.

Spectator Ions

Ions that appear unchanged on both sides of a chemical equation and do not participate in the reaction.

Steps for Net Ionic Equations

1. Write the balanced molecular equation. 2. Expand strong electrolytes into ions. 3. Cancel spectator ions.

Strong Electrolytes

Substances that dissociate completely into ions in solution, such as strong acids, strong bases, and soluble salts.

Weak Electrolytes

Substances that do not fully dissociate in water, such as weak acids and weak bases.

H+ vs H3O+

In aqueous solutions, H+ is shorthand for H3O+, the hydronium ion.

Strong Acid + Strong Base Reaction

HCl + NaOH → NaCl + H2O

Total Ionic Equation for Strong Acid + Strong Base

H+ + Cl− + Na+ + OH− → Na+ + Cl− + H2O

Net Ionic Equation for Strong Acid + Strong Base

H+ + OH− → H2O

Result of Strong Acid + Strong Base Reaction

The solution contains only a neutral salt and water; pH ≈ 7.

Strong Acid + Weak Base Reaction

Occurs when a strong acid donates a proton to a weak base, forming its conjugate acid.

Example: HCl + NH3 → NH4Cl

The hydrogen ion protonates the weak base ammonia to form ammonium.

Net Ionic Equation for Strong Acid + Weak Base

H+ + B → BH+

Result of Strong Acid + Weak Base Solution

The conjugate acid BH+ dominates, so the solution is acidic.

Strong Acid + Weak Base (Anion Form) Example

HI + NaHCOO → HCOOH + NaI

Net Ionic Equation for Strong Acid + Weak Base (Anion Form)

H+ + A− → HA

Result of Strong Acid + Weak Base (Anion Form)

The strong acid converts the weak base anion into its conjugate acid; the solution is acidic.

Weak Acid + Strong Base Reaction

A reaction where a weak acid donates a proton to hydroxide, forming its conjugate base and water.

Example: HOCl + NaOH → NaOCl + H2O

Net Ionic Equation for Weak Acid + Strong Base

HA + OH− → A− + H2O

Result of Weak Acid + Strong Base Solution

The solution is basic due to the conjugate base A−.

Weak Acid + Weak Base Reaction

Both are weak; neither fully dissociates; equilibrium position depends on relative Ka and Kb.

Result of Weak Acid + Weak Base Reaction

The pH depends on which conjugate pair is stronger; the mixture may be acidic, basic, or near neutral.

Titration

A controlled neutralization reaction used to determine an unknown concentration.

Titrant

The solution of known concentration delivered from a burette during a titration.

Analyte (Titrand)

The solution of unknown concentration in the flask being titrated.

Equivalence Point

The chemical point where stoichiometric amounts of acid and base have reacted completely.

Endpoint

The observable signal (such as a color change) indicating the titration should stop.

Relationship