Solutions and Concentrations

Solutions

• A solution is a homogenous mixture containing two or more substances.

• It consists of a solute dissolved into a solvent.

• Water is a universal solvent, meaning many substances can dissolve in it.

• Non-polar molecules like fat do not dissolve in water.

• Solubility measures how a solute can dissolve into a solvent.

• A saturated solution means the maximum amount of solute has been dissolved into a certain volume of solvent.

• Anything with a polar charge dissolves in water.

• Substances that have oxygen are usually going to be polar.

• Non-polar molecules often have lots of carbon and hydrogen (hydro-carbon molecules);

• Fatty-acids are examples of molecules with carbon and hydrogen.

High Specific Heat

• Water has a high specific heat, meaning it takes a lot of energy to increase its temperature.

Concentrations

• Concentration is the amount of solute that has been dissolved in a solvent.

• Different units are used depending on the application:

  • Molarity (M): Moles per liter

    • M = \frac{Moles}{L}

    • One mole of a substance equals its molecular mass in grams.

  • Molality: Moles per kilogram

    • m = \frac{Moles}{Kg \ of \ Solvent}

  • Mole Fraction:

    • X = \frac{Moles \ of \ solute}{Total \ Moles \ Present}

  • Mass Percentage: (Mass of solute (g) / Mass of solution (g)) * 100

    • \frac{Mass \ of \ Solute(g)}{Mass \ of \ Solution(g)} * 100

  • Parts Per Thousand (ppt):

    • \frac{g \ solute}{kg \ Solution}

  • Parts Per Million (PPM):

    • \frac{mg \ Solute}{kg \ Solution}

  • Parts Per Billion (PPB):

    • \frac{\mu g \ Solute}{kg \ Solution}