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Classic Experiments for General Chemistry
23
Classic Experiments for General Chemistry,
continued
Determination of Ka of Weak Acids—Laboratory Kit By: The Flinn Staff
Students measure the Ka value for the ionization of two unknown weak acids. Solutions containing equal molar amounts of the weak acids and their conjugate bases are prepared by “half-neutralization” of the acid. Their pH values are measured and used to calculate the pKa value for each unknown weak acid. These values are compared to a provided list of weak acid Ka values to determine the identity of each acid. This labo- ratory challenges the students’ understanding of the relationship among Ka, pH and H3O+ concentration while providing the recommended familiarity with the use of pH meters.
Complete for 24 students working in pairs.
The Determination of Keq for FeSCN2+—
Laboratory Kit
By: The Flinn Staff
In this two-part lab, students determine the equilibrium constant for the reaction of iron(III) ions with thiocyanate ions (SCN-). In Part 1, a series of reference solutions containing the product ion, iron(III) thiocyanate (FeSCN2+), is prepared. Students then make up test solutions containing a fixed amount of iron(III) ions and different amounts of the SCN- ion. These solutions are analyzed in Part 2 using a colorimeter. The first set of solutions is used to generate a calibration curve of absorbance versus the concentration of FeSCN2+ ions. The second set of solutions is then analyzed and the FeSCN2+ ion concentration of each solution is deter- mined. The students use the data to calculate the equilibrium constant for the reaction of iron(III) ions with thiocyanate ions (SCN-). Students gain valuable experience in the techniques of quantitative transfer, along with the process of colorimetric determination.
Complete for 24 students working in pairs.
Kinetics of a Reaction—Laboratory Kit
By: The Flinn Staff
Students study the kinetics of a clock reaction involving the oxidation of iodide ion by bromate ion in the presence of an acid. First, students study the effect of concentration on the rate of reaction to determine the order of reaction for each reactant and the rate constant. Second, the activation energy is determined by varying the temperature, measuring the rate, and calculating the rate constant at different temperatures. Finally, the effect of a catalyst on reaction rate is studied.
Students gain valuable experience with kinetics calculations and microscale techniques. They also understand why the changes in concen- tration, temperature, and the use of a catalyst are made in each part of the experiment, and how these changes lead to the calculated quantities.
Complete for 24 students working in pairs. Two reusable 12-well reaction strips are recommended for each student group and are avail- able separately.
Determination of Ka of Weak Acids—Laboratory Kit AP7951
Classic Experiments for General Chemistry—22-Kit Bundle
Save by ordering the complete Guided-Inquiry Experiments for General Chemistry—22-Kit Bundle! Comprehensive, cost-saving bundle includes all 22 of the kits on pages 21–26.
Catalog No.
Description
Price/Each
AP7966
Classic Experiments for General Chemistry—22-Kit Bundle
$1318.00
Catalog No.
Description
Price/Each
AP7951
Determination of Ka of Weak Acids—Laboratory Kit
$42.40
Catalog No.
Description
Price/Each
AP7952
The Determination of Keq for FeSCN2+—Laboratory Kit
$32.80
CLASSIC EXPERIMENTS FOR GENERAL CHEMISTRY continued on next page.
The Determination of Keq for FeSCN2+—Laboratory Kit AP7952
Catalog No.
Description
Price/Each
AP7953
Kinetics of a Reaction—Laboratory Kit
$61.45
Kinetics of a Reaction—Laboratory Kit AP7953