Featured in PASCO’s College Chemistry Instructor Guide

College Chemistry Instructor Guide

(PS-3803A)

College Instructor edition with 36 experiments covering introductory and general chemistry topics.

Ka Values of Acids

Lab Summary

Use a pH sensor and drop counter to determine the acidity constants of two isomeric multi-protic acids and relate the acidity constants to their structural differences.

Theory

Students determine the acidity constants of two isomeric multi-protic acids, use these values to identify the acids, and provide an explanation for the difference in values based on molecular force considerations.

Method

Students will gain experience conducting the following procedures:

  • Determining the pKa of the multiple equivalence points of two isomeric multi-protic acids (fumaric acid and maleic acid) through titration.
  • Using a pH sensor and drop counter to perform titration measurements and determine equivalence points and solution concentrations.

Sensors / Equipment Used:

PASPORT Chemistry Sensor

(PS-2170)

Allows students to measure Temperature, pH/ISE/ORP, Absolute Pressure & Voltage in one sensor. For use with PASPORT Interfaces.

PASPORT High Accuracy Drop Counter

(PS-2117)

Is a professional drop counter that allows students to capture detailed titration data. For use with PASPORT Interfaces.

Materials Used:

Micro stir bar
Ring stand 
Clamp, right-angle 
Clamp, buret 
Beaker, 250-mL - 2
Beaker, 25-mL - 2
Buret , 50-mL 
Graduated cylinder, 100-mL 
Magnetic stirrer 
Unidentified fumaric acid solution - 50 mL
Unidentified maleic acid solution - 50 mL
0.500 M Sodium hydroxide (NaOH) - 150 mL
Funnel 
Buffers, pH 4 and pH 10 - 10 mL
Wash bottle with deionized water 
Cotton swab or tissue 

The Associated Bundle:

Advanced Chemistry Standard Sensor Bundle

(PS-2928A)

Contains the probeware for completing experiments in the College Chemistry lab manual.

Interface Required

This experiment may require software and an interface for data collection.