Virtual Experiment 12

Solution Stoichiometry

The following discussion and videos will show you real titrations and calculations of an acid base titration. The Virtual Experiment 12 laboratory assignment will be completed this semester.

The assignments that must be completed are:

Complete the pre laboratory problems before coming to the class meeting.
Complete the laboratory report using the following simulations, data and resources.
- Part A:
  1. Using the Virtual Laboratory simulation at http://chemcollective.org/vlab/101 and the following procedure, practice the titration of NaOH using a KHP solution and phenolphthalein. Report the molarity of the NaOH solution.
  2. Using the provided information in the class data, choose three trials for the standardization of the NaOH solution (part A). Complete all calculations and questions in the report.
- Part B
  1. Using the Virtual Laboratory simulation at http://chemcollective.org/activities/autograded/131 , practice the titration of Vinegar using a standardized NaOH solution and phenolphthalein. Report you volume, mass of solution, molarity of the vinegar solution and the % by mass.
  2. Using the provided information in the class data, choose three trials for the titration of the vinegar solution (Part B). Complete all calculations and questions in the report.

Discussion

Volumetric glassware which includes pipets, flasks and burets. The buret is a long tube that is calibrated with small markings which can be used to determine volumes with both precision and accuracy. This is the basis of volume stoichiometry. Most volumetric glassware is precise, being able to measure volumes to less than a 1% error or to + 0.01 mL. With the ability to measure volume delivered into a mixture and mass of a substance with great precision, we are able to use stoichiometry to determine the concentrations of solutions by knowing the mole ratio of the reactants or to determine the number of moles by using the concentration of the solution. The mass of the solid being titrated allows us to calculate the moles of the reactant.

moles of solute (KHP) = mass of solute / molar mass

A detailed discussion is available on the Experiment 12 website.

Experiment12

Virtual Experiment12

Pre laboratory assignment

The pre laboratory problems are questions about the laboratory assignment, background, definitions or procedure and calculations.

pre lab Virtual Experiment12

Procedure

The laboratory report of the assignment contains questions, data collection, calculation and reporting of results.

Part A: Standardization of sodium hydroxide solution

Traditionally we would prepare the NaOH solution from either a more concentrated solution or from NaOH pellets.

V-Experiment12Report

Part I of Part A of the laboratory assignment will be completed using a simulation.

Using the Virtual Laboratory simulation at http://chemcollective.org/vlab/101 and the following procedure, practice the titration of NaOH using a KHP solution and phenolphthalein. Report the molarity of the NaOH solution.

Lab 12 introduction - indicators.mp4

This video introduces Experiment 12 with the preparation of the NaOH solution and how the titration will be performed with an indicator.

Lab 12 Part A simulation.mp4

This video shows the simulation of the titration of a KHP solution with a NaOH solution and the calculations needed to determine the molarity of the NaOH solution.

Part 2 of Part A of the laboratory assignment will be completed using class data.

Using the class data, choose three trials to complete the calculation of the standardization of the prepared NaOH with the primary standard KHP.

Experiments 12 ClassData

KHP titration.mp4

This video shows the titration of a mass of KHP with a 0.2 M solution of NaOH using phenolphthalein indicator. Calculations of how to determine the molarity of the NaOH solution are explained.

vinegar titration.mp4

This video shows the titration of a white vinegar solution with the standardized NaOH solution from Part A. Calculation of how to determine the molarity and % mass of the vinegar solution are explained. The simulation is briefly mentioned.

Part B: Analysis of Vinegar

Part I of Part B of the laboratory assignment will be completed using a simulation and class data.

Using the Virtual Laboratory simulation at http://chemcollective.org/activities/autograded/131 , practice the titration of Vinegar using a standardized NaOH solution and phenolphthalein. Report you volume, mass of solution, molarity of the vinegar solution and the % by mass.

Part 2 of Part B of the laboratory assignment will be completed using a simulation and class data.

Using the class data, choose three trials to complete the calculation of the determination of the molarity and % mass of vinegar

Calculating the concentration of acetic acid in vinegar solution: https://youtu.be/5-nAF9QadeI and https://youtu.be/LQv6hLY2dyg

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