Notes from a workshop held at the Dutch Neck School, West Windsor, NJ, May 18, 1998, by Steve Hoagland

VOCABULARY

  • Acids and bases: Click HERE
      
  • Carbohydrate - Important organic compounds found in plants.  They are polymers composed of simple sugar units (see Polymer and Saccharide, below).  Cellulose, starch, pectin, and common sugars are carbohydrates.
     
  • Crystallization - Slow deposition of crystalline solid from a saturated solution
     
  • Decant - Carefully pour off upper liquid layer without disturbing sediment or lower liquid  layer.
     
  • Filtrate - Material (usually a solid) that has passed through a filter.
     
  • Glucose - One of the many sugar unit building blocks of carbohydrates.  Glucose is the monomer (see Polymer, below) that reacts with itself to form cornstarch, cellulose, and glycogen.
     
  • Hydrate - A crystalline form that contains water.  When hydrates are heated, some or all of the water is released from the crystal into the air.
     
  • pH - A scale of acidity and basicity.  A neutral solution has pH = 7.  Lower pH means more acid, higher pH means more basic.
     
  • Polymer - A large molecule formed in a process wherein small organic compounds (monomers - from Greek meaning one part) react with each other.  Dimers are formed from two small unit molecules, trimers from three, and so forth.
     
  • Precipitate - Amorphous solid or very small crystals brought out of solution abruptly by some action or process.  To cause a precipitate to come out of solution.
     
  • Saccharide - The simplest structural units in a carbohydrate.  These units are also called sugars.
     
  • Saturated solution - A solution that has reached its limit of the amount of solute that can be dissolved at a specified temperature.
     
  • Solution - A homogenous mixture, generally produced by mixing either a solid, liquid, or gas into a liquid.  (See Solvent and Solute below).   The process in which a solution is formed is sometimes referred to as dissolution.
     
  • Solvent - The substance (usually a liquid) into which another substance is mixed to form a solution.  For example, when sugar is dissolved in water, water is the solvent.
     
  • Solute - The substance which is dissolved into the solvent to form a solution.
     
  • Supernatant - transparent liquid layer covering a sediment, precipitate, or mass of crystals.
    •

    Acids and Bases - a brief introduction

    As you probably know, water is composed of molecules with the formula H2O.  This means that one water molecule is made of two hydrogen atoms and one oxygen atom. These atoms are connected like this:  H-O-H
    It happens that water molecules come apart a little bit, to form two ions Ions are molecules or atoms with electrical charges on them.
    The two ions from water are H+ and O-H- The + and - signs mean that these ions have a positive and negative charge, respectively.
    Each water molecule gives one H+ and one O-H-.  So pure water is neutral, that is it has equal concentrations of H+ and one O-H-.  

     
    Now when we dissolve things in water:
    Some things increase the concentration of H+
    Some things increase the concentration of O-H.
    It happens that H+ and O-H- are very reactive.   So when we have a solution in which the concentrations of O-H- and O-H- are not equal, this solution has interesting properties.

    A solution in which H+ is much greater than O-H- is called an acidic solution, and the substance we dissolved that caused this to happen is called an acid.

    If O-H- is much greater than H+ the solution is called basic and the substance we dissolved that caused this to happen is called a base.

    Both strongly acid and strongly basic solutions can dissolve many otherwise insoluble substances, so they can eat away at things.

    		 That is, they can cause certain chemical changes to occur.

    CONTENTS

    Introduction
    Time Management Tips
    Vocabulary
    Comments on the Lessons    		     Chemical Identities and Names of the Unknowns
    Interpreting the Results of the Tests
    Supplementary Extensions
    Tested Experiments
    Bibliography

    Last edited September 20, 2000