Analytical Chemistry I Quiz

Study Notes

Analytical Chemistry is the branch of chemistry concerning the separation, identification, and determination of components in a sample.
It's divided into qualitative analysis (identifying components) and quantitative analysis (measuring components' concentration).
Quantitative analysis methods include volumetric analysis (using titrations), gravimetric analysis (converting a sample to an insoluble form), and instrumental analysis (using instruments).

Titration is a process to measure the volume of a standard solution (titrant) needed to react with the analyte (sample of unknown concentration) to reach the endpoint
Requirements of a titration reaction include
- Single/Complete reaction - avoiding side reactions
- Rapid reaction - instantaneous
- Stoichiometric reaction (balanced chemical equation)
- Easy-to-detect endpoint (using a visual indicator or instrumental methods)

Ionic combination reactions
- Neutralization: H⁺ + OH⁻ → H₂O
- Precipitation: Ag⁺ + Cl⁻ → AgCl↓
- Complexation: Ag⁺ + 2CN⁻ → [Ag(CN)₂]⁻
Electron transfer reactions (Redox reactions):
- Ce⁴⁺ + Fe²⁺ → Ce³⁺ + Fe³⁺

The reaction between sample and standard needs to be both simple and expressible via a chemical equation
The reaction must be single – avoiding side reactions
A suitable standard solution (titrant) must be available for the sample
An easy-to-detect endpoint is necessary
The reaction must be fast or use a catalyst.

Primary Standards:
- Easily obtained in extremely high purity, well-characterized, known compositions
- Stable, non-volatile, non-hygroscopic, and readily soluble in solvents
- Examples include Potassium acid phthalate, benzoic acid, anhydrous sodium carbonate, and constant boiling point hydrochloric acid
Secondary Standards:
- Do not fully meet the requirements of primary standards.
- They are standardized by comparing them to primary standards.
- Examples include oxalic acid and borax.

Direct method (Involves 1 step for preparation: used for primary standards)
Indirect method (Involves 2 steps for preparation and standardization: used for secondary standards)

Electrolytic Dissociation Theory describes the dissociation of electrolytes into ions in water
Degree of Dissociation = number of dissociated solute molecules/Total number of solute molecules before dissociation
Electrolytes classified as strong (close to 1 degree dissociation) and weak (dissociation ≠ 1).

Arrhenius Theory: Acids dissociate to give H⁺; bases dissociate to give OH⁻—limited in scope.
Brønsted-Lowry Theory: An acid is a proton donor, and a base is a proton acceptor.
Lewis Theory: An acid is an electron pair acceptor, and a base is an electron pair donor.