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What is Solution Stoichiometry?

Solution stoichiometry deals with reactions in solutions.

Types of Solution Reactions

   – Precipitation

   – Acid-base

   – Oxidation-reduction

   – Titrations

1.   Precipitation

            Precipitation reactions occur when a solid is formed from the mixing of two or more solutions.  To determine whether a reaction will form a precipitate (a solid), you need to first see what each reactant breaks up into.  Afterwards, find out what products are formed and then look at the solubility rules to determine whether the compound is soluble or not.  If it is insoluble then a precipitate reaction has occurred.

2.   Acid-base

            Acid-base reactions are reactions involving either an acid or base. There are 3 definitions for an acid and a base. 

            Bronsted-Lowry definition: Acids are proton donors and Bases                             are proton acceptors.

            Lewis definition: Acids are electron acceptors and Bases are electron             donors. 

            Arrhenius definition: Acids produce H+ and Bases produce OH-.

3.   Oxidation-Reduction

            Oxidation-reduction reactions are reactions in which electrons are transferred between the reactants and products.  Oxidation occurs when a reactant loses an electron and reduction occurs when a reactant gains an electron.  A simple way to remember this is LEO the lion goes GER. (Lose Electrons = Oxidation, Gain Electrons = Reduction).  

            Reducing agents = electron donors

            Oxidizing agents = electron acceptors

4.   Titrations

A titration is when you add a strong acid and a strong base at a precise amount so that the pH of the solution will become 7, or the equivalence point. You can determine the equivalence point by using an indicator, which changes the color of the solution when the solution reaches a certain pH. Phenolphthalein is a base indicator that indicates when a solution is over the pH of 9, it will turn pink. The endpoint of the solution is when the whole solution turns to the color. In order for a titration to be successful, the following must happen:

  1. The reaction between the known and unknown solutions must be determined.
  2. The equivalence point must be accurately determined.
  3. The volume of the known solution needed to reach the equivalence point must be known.

When the process is done correctly, it is known as an acid-base reaction.

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