C8 Chemical Analysis

Pure Substance

Contains only one type of compound or element.

Melting and Boiling Points of Pure Substances

Only pure substances melt and boil at specific temperatures.

Water Boiling Point

Water boils at 100 degrees Celsius under standard atmospheric conditions.

Impurities

Lower the melting point and increase the boiling point of a substance.

Formulation

A mixture prepared using a specific formula with precise amounts of different components.

Paper Chromatography

Technique to separate dyes where different dyes move up paper at different rates.

Mobile Phase

The substance molecules can move in (solvent) during chromatography.

Stationary Phase

The substance molecules can’t move in (paper) during chromatography.

Rf Value

Ratio of distance traveled by the substance to distance traveled by the solvent.

Test for Chlorine Gas

Blue litmus paper turns red then bleaches white in chlorine presence.

Test for Oxygen Gas

Glowing splint relights in the presence of oxygen.

Test for Hydrogen Gas

Produces a squeaky pop sound when ignited.

Test for Carbon Dioxide Gas

Bubble into limewater; if cloudy, CO2 is present.

Anions

Negatively charged ions.

Test for Carbonates

Add dilute HCl; if CO2 produced, goes cloudy with limewater.

Test for Sulfates

Add barium chloride; white precipitate indicates sulfates are present.

Test for Halide Ions

Add silver nitrate; forms precipitate indicating presence of halide ions.

Cations

Positively charged ions, mainly metal ions except ammonium.

Flame Test for Lithium Ions

Produces a crimson flame.

Flame Test for Sodium Ions

Produces a yellow flame.

Flame Test for Potassium Ions

Produces a lilac flame.

Flame Test for Calcium Ions

Produces an orange-red flame.

Flame Test for Copper Ions

Produces a green flame.

Flame Emission Spectroscopy

Technique that detects light emitted by heated metal ions to identify them.

Unique Line Spectrum

Each metal ion emits a unique combination of wavelengths, producing a distinct pattern.

Benefits of Instrumental Methods

Accurate, sensitive, and fast methods for detecting substances.