Minh-Huy Tran AP Chemistry Period 2 & 3 10/15/2018 Piedmont Hills High School AP Chemistry 2018-2019 Laboratory Experiment 3 – Acid-Base Titration October 12th, 2018 Purpose: 1. Find the actual concentration of the prepared NaOH solution by standardizing the NaOH solution by titrating with KHP (Potassium Acid Phthalate). 2. Find the actual concentration of the prepared HCl solution by standardizing the HCl solution by titrating with the standardized NaOH solution. 3. Determine the concentration of the unknown HCl solution by titrating with the standardized NaOH solution. Introduction: 1. Processes and Principles This laboratory experiment focuses on the process of titration. Titration is the slow addition of one solution of a known concentration (titrant) to a known volume of another solution of unknown concentration (titrand) until the reaction reaches neutralization, which is often indicated by a light color change. Specifically, in this laboratory experiment, either an acid or base will be the titrant or titrand, and an indicator will determine if neutralization occurred through a light color change. The process of titration for this laboratory experiment is listed below. Steps for Titration: 1. Fill the burette with known concentration of an acid or base 2. Take a burette reading from the top of the meniscus, and record it. 3. Place a Erlenmeyer flask on the base of the ring stand containing a known volume and an unknown concentration of acid or base 4. Add a few drops of the appropriate indicator to the flask 5. Slowly add your titrate from the burette to the flask while stirring 6. Keep adding the titrate until a light color change happens and stabilizes for about 30 seconds. 7. Take a final reading of the burette, record it.
The laboratory experiment also focuses on the principle of Molarity. Molarity is the concentration of a solution expressed as the number of moles of solute per liter of a solution. The moles of a solute can be calculated from the amount of grams of a substance that is used and volume can be calculated through metric conversions. The formula for Molarity is M=mol/l. The formula, M 1 V 1 = M 2 V 2 , is also needed in this laboratory experiment. The formula is used to determine the concentration of the unknown solution (titrand) much more efficiently. However, this formula is used if the number of moles of the reactants are 1:1. If not, stoichiometry is required to figure out the concentration of the unknown solution (titrand). 2. Definition of Terms a. Acid-base reaction→ reaction where acid donates a proton to the base; a neutralization reaction b. Neutralization→ when the pH of the system is a neutral pH of 7 c. Solution concentration→ amount of solute dissolved in a solution d. Molarity→ measurement of solution concentration; M = molesof solute Lof solution e. Solute→ substance(s) that are in the solution which is not the solvent.
- Summer '14