Chemistry Lecture: Molecular Mass, Concentration, and Dilutions

Vocabulary terms covering molecular mass, nomenclature, solution components, units of concentration, and dilutions based on Chapter 1-9 lecture notes.

Molecular Mass

The total mass of a molecule calculated by summing the atomic mass of each constituent element multiplied by the number of atoms of that element in the molecule; mathematically represented as $\sum (a_i \times \text{atomic mass}_i)$.

Molar Mass

A term that is completely equivalent to and means the exact same thing as molecular mass, expressed in units of grams per mole ($g\,mol^{-1}$).

$$FeCl_3$$

An ionic compound containing iron in a $+3$ oxidation state and three chloride ions, named iron(III) chloride.

$$Cr(H_2PO_4)_3$$

An ionic compound named chromium(III) dihydrogen phosphate, composed of chromium with a $+3$ charge and three dihydrogen phosphate polyatomic ions.

Solute

The component of a solution that is present in a lesser amount.

Solvent

The component of a solution that is present in a greater amount.

Molarity

The standard scientific unit of concentration, abbreviated as $M$, defined as the number of moles of solute per volume of solution in liters ($\text{moles}/\text{liter}$).

Mass to Mass Percent ($\%m/m$)

A concentration calculation defined as the grams of solute divided by the grams of solution, multiplied by $100$.

Mass to Volume Percent ($\%m/v$)

A concentration calculation defined as the grams of solute divided by the milliliters of solvent, multiplied by $100$.

Volume to Volume Percent ($\%v/v$)

A concentration calculation defined as the milliliters of solute divided by the milliliters of solution, multiplied by $100$.

Parts Per Million ($\text{PPM}$)

A unit of concentration frequently used for trace contaminants, defined as milligrams of solute divided by liters of solvent.

Parts Per Billion ($\text{PPB}$)

A unit of concentration used for very dilute substances, defined as nanograms of solute divided by liters of solvent.

Dilution

The process of adding solvent to a solution to decrease its concentration, governed by the formula $M_1 V_1 = M_2 V_2$.