Lecture Notes: Solutions and Concentration

Understanding Matter and Solutions

• Matter can exist as pure substances (compounds or elements) or mixtures.
• Mixtures:
  • Homogeneous mixtures, also known as solutions.
  • Examples include air (the atmosphere) or saltwater (seawater).

Key Definitions

• Solution Composition: Described by concentration, the relative amount of a component within a solution.

• Solvent:

  • The component in the greatest amount in a solution.
  • Example: Water in seawater.

• Solute:

  • The substance dissolved in the solvent.
  • Example: Salt in seawater.

• Dilute Solution: Little solute present.

• Concentrated Solution: Large amount of solute present.

• Aqueous Solution: Solution where water is the solvent.

Measuring Concentration: Molarity

• Molarity (M): Moles of solute per liter of solution.
• Calculating Molarity:
  • Formula: M = moles of solute / liters of solution.
  • Example Calculation:
    • Given: 355 ml soft drink with 0.133 moles of sucrose.
    • Convert 355 ml to liters: 0.355 L.
    • Molarity = 0.133 moles / 0.355 L = 0.375 M.

Practical Applications

• Molarity calculations help determine:
  • Amount of a solute in a given volume of solution.
  • Volume of solution needed for a certain amount of solute.
• Useful for calculations in various fields, such as chemistry and environmental science.

These notes summarize key concepts from the lecture on solutions and concentration, providing a foundational understanding of how to measure and calculate the concentration of solutions using molarity.