Lecture: Concentration Calculations

Introduction to Concentration

Concentration measures the strength of a solution, indicating how dilute or concentrated it is.
Examples include preferences for strong or weak beverages and the high salt content of the Dead Sea.

Concentration is measured by the amount of solute in a solution.
- Solute: The substance dissolved in a solution (lesser quantity).
- Solution: The mixture of solute and solvent.
Key equation: Solute over solution.

Mass Percent: Amount of solute in grams over the amount of solution in grams, expressed as a percentage.
- Formula: ( \text{Mass percent} = \frac{\text{grams of solute}}{\text{grams of solution}} \times 100 )
- Example: 10% sulfuric acid solution indicates 10 grams of solute per 100 grams of solution.
Volume Percent: Used less frequently in this lecture.
Mass/Volume Percent: Grams of solute per milliliters of solution.
- Example: In a 15% solution, 15 grams of solute per 100 mL of solution.

Molarity (M) is a unit of concentration measuring moles of solute per liter of solution.
Commonly used in labs though less so in everyday applications.
Example: 1 M sodium chloride solution requires 1 mole of NaCl dissolved in 1 liter of solution.
Not deeply covered as it's not widely used in certain professions (e.g., nursing).

Example 1: 8 grams of KCl in 50 grams total solution.
- Formula: ( 8, \text{g} / 50, \text{g} \times 100 = 16% )
Example 2: 35 grams solute in 135 grams solution (after adding water).
- Formula: ( 35, \text{g} / 135, \text{g} \times 100 = 26% )

Concentration calculations are crucial for quantifying how strong or dilute a solution is.
Understanding these concepts is essential, especially in laboratory settings where precise measurements are critical.