Neutralization Reactions and Titrations
Neutralization:
A neutralization reaction between an acid and a base in aqueous solution produces an ionic compound (generically referred to as a salt) and water. It can be described as a double exchange reaction in which the two compounds exchange cations. The pH of the product approaches 7. This is because the H⁺ and OH⁻ ions are being converted into water molecules. As their concentrations decrease, the pH will move closer to 7.
Titrations:
A titration is a procedure in which a neutralization reaction is monitored with an indicator (such as phenolphthalein) allowing you to calculate the unknown concentration of an acid or base
If the solution is acidic, a standard base solution is added until it is neutralized and vice versa.
The end point is indicated by a color change and is when the number of H⁺ ions is equivalent to the number of OH⁻ ions. Calculations are based off of the following formula
(Volume of acid)(Molarity of H⁺) = (volume of base)(Molarity of OH⁻)
Mol Ratios
Balanced Equations show ratios usually in terms of moles.
2Al₂O₃ ---> 4Al + 3O₂
(For every 2 moles of Al₂O₃ that is used, 4 moles of Al and 3 moles of O₂ are produced)
Mole-Mole Problems:
The quantity of one or more reactants is given in moles. The quantity of products in moles is requested. The mole ratio is used to calculate.
Excess and Limiting Reactants:
If reactants are not combined in their mol ratio, one will run out and the other will be excess. The one that runs out is called the limiting reactant. The limiting reactant (or limiting reagent) in a chemical reaction is the substance that is totally consumed when the chemical reaction is complete. The amount of product formed is limited by this reagent as the reaction can not continue.
To determine the limiting reactant:
Percent Yield
% yield = actual yield/theoretical yield x 100%