exp 1 study guide

Polarity

A property of a molecule that results from the distribution of electrons, leading to a positive and a negative end.

Criteria for selecting recrystallization solvent

Should dissolve the compound well at high temperature and poorly at low temperature.

Recrystallization

A purification technique that removes impurities from a solid compound by dissolving it in a hot solvent and allowing it to slowly crystallize as it cools.

Solubility and Temperature relationship

Generally, solubility increases with an increase in temperature for many solids.

Solubility and Intermolecular Forces (IMFs) relationship

Stronger intermolecular forces lead to lower solubility; substances with similar IMFs are more likely to dissolve in one another.

Melting point temperature and purity relationship

Purity of a substance is indicated by a sharp melting point; impurities lower and broaden the melting point range.

Percent recovery formula

Percent recovery = (mass of pure compound recovered / mass of impure compound used) x 100%.

Purpose of vacuum filtration

To quickly separate solids from liquids and remove impurities from a solution.

Filtration: What is in the filtrate

The liquid that passes through the filter and contains dissolved substances.

Filtration: What is in the precipitate

The solid that remains on the filter and contains undissolved substances.

Order of reagents in recrystallization

Each reagent is used in a specific order to optimize solubility and improve purification.