Engineering Fundamentals: Water & Wastewater Concentration & Density Review

Vocabulary flashcards covering core concepts in environmental engineering measurements, concentration units, molarity, density, and atomic weights based on Dr. Sarah Bauer's lecture notes.

Concentration

The 'amount' of a substance per 'amount' of containing material (such as air, water, or soil), serving as a key determinant of chemical fate, transport, and treatment in environmental systems.

Molecular Weight ($\text{MW}$)

The sum of the atomic weights of all atoms in a chemical formula ($\text{Molecular weight} = \sum \text{Atomic weights}$), used to convert between mass in grams and amount in moles ($\text{Mass in grams} = \text{Molecular weight} \times \text{Number of moles}$).

Element Tile Layout

A standard periodic table box entry displaying the element name (e.g., Hydrogen), atomic weight ($1.0080$), chemical symbol ($\text{H}$), and atomic number ($1$).

Incompressible Liquid

A fluid property assumed for liquid water in all environmental engineering applications, meaning its volume and density do not significantly change under applied pressure.

Parts Per Million ($\text{ppm}_m$)

A mass chemical per total mass unit defined as $1\,\text{mg}$ of solute per $1\,\text{kg}$ total mass ($1\,\text{mg/kg}$), or $1\,\text{g}$ of chemical per $10^6\,\text{g}$ total mass.

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

A concentration unit representing $1\,\text{g}$ of chemical per billion ($10^9$) grams total, equal to $1\,\mu\text{g/kg}$ in solid matrices or $1\,\mu\text{g/L}$ in aqueous solution.

Parts Per Trillion ($\text{ppt}$)

A mass-based concentration unit representing $1\,\text{g}$ of chemical per trillion ($10^{12}$) grams of total mixture.

Aqueous $1\,\text{ppm}$ Equivalence

In dilute aqueous solutions, $1\,\text{ppm}$ is equal to $1\,\text{mg/L}$ because the density of water is approximately $1000\,\text{g/L}$.

Molarity ($M$)

A concentration unit defined as the number of moles of a chemical compound dissolved per liter of solution ($\text{moles/L}$).

Trichloroethylene (TCE)

An environmental chemical contaminant with a molecular weight of $131.5\,\text{g/mol}$.

Density

A physical property of matter defined as mass per unit volume ($\text{Density} = \frac{\text{Mass}}{\text{Volume}}$), determining buoyancy in heterogeneous mixtures.

Molar Concentration of Pure Water

The molarity of pure water calculated by dividing its density ($997\,\text{g/L}$) by its molecular weight ($18.0\,\text{g/mol}$), giving $55.4\,\text{mol/L}$.

Atomic Weight of Chlorine ($\text{Cl}$)

The standard atomic weight for chlorine used in environmental calculations, equal to $35.45\,\text{g/mol}$.

Atomic Weight of Carbon ($\text{C}$)

The standard atomic weight for carbon, equal to $12\,\text{g/mol}$ (with $14$ representing its radioactive isotope form).