Most fish need at least 4 ppm dissolved O₂ in water for survival. (a) What is this concentration in mol/L?

Key Concepts

Dissolved Oxygen Concentration

Dissolved oxygen (DO) refers to the amount of oxygen that is present in water, which is crucial for aquatic life. The concentration of DO is typically measured in parts per million (ppm) or milligrams per liter (mg/L). For fish, a minimum concentration of 4 ppm is necessary for survival, indicating the importance of oxygen availability in aquatic ecosystems.

Molarity (mol/L)

Molarity is a way to express concentration, defined as the number of moles of solute per liter of solution (mol/L). It is a fundamental concept in chemistry that allows for the quantification of substances in a solution. To convert ppm to molarity, one must consider the molar mass of the solute and the density of the solution, as ppm is a mass-based measurement.

Conversion between ppm and molarity

To convert a concentration from ppm to molarity, the formula used is: molarity (mol/L) = (ppm / molar mass of solute) × (1/1000). This conversion is essential for understanding how mass-based concentrations relate to the number of moles in a given volume, which is critical for chemical calculations and understanding biological needs in aquatic environments.