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Measuring Acid Strength—Ka Values of Weak Acids—Student Laboratory Kit

By: The Flinn Staff

Item #: AP6364

Price: $32.55

In Stock.

The Measuring Acid Strength Chemistry Laboratory Kit presents students with the theory of acidity, equilibrium and constants. The experiment presents a methodology for finding that the pH of the solution is equal to the pKa of the acid.

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Product Details

Do your students understand why some acids have lower pH values than others, even though their concentrations are the same? Acids vary greatly in their strength—their ability to produce hydrogen ions when dissolved in water. This lab will help you explain this concept and teach students about equilibrium constants for weak acids. Students neutralize exactly half of a solution of a weak acid. This gives them a solution containing an equal molar amount of the weak acid and its conjugate base. The pH of the solution is equal to the pKa value of the acid. Kit includes four different weak acid salts—use them as unknowns or let students match their results against the literature. Accurate results ensure that you will be successful with either approach! Includes reproducible student handouts, detailed background information, Teacher Notes with sample data and answers to questions and all necessary chemicals.

Complete for 30 students working in pairs. pH meters, sensors or probes are required and available separately. This is an excellent experiment for using your technology probeware.


Materials Included in Kit: 
Phenolphthalein solution, 0.5%, 30 mL
Potassium bisulfate, 4 g
Potassium bitartrate, 4 g
Potassium hydrogen phthalate, 4 g
Potassium phosphate, monobasic, 4 g
Sodium hydroxide solution, 0.1 M, 500 mL
Pipet, Beral-type, thin stem, 30

Correlation to Next Generation Science Standards (NGSS)

Science & Engineering Practices

Planning and carrying out investigations
Analyzing and interpreting data
Using mathematics and computational thinking

Disciplinary Core Ideas

MS-PS1.B: Chemical Reactions
HS-PS1.B: Chemical Reactions

Crosscutting Concepts

Scale, proportion, and quantity
Energy and matter

Performance Expectations

HS-PS2-1: Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration.
HS-PS2-2: Use mathematical representations to support the claim that the total momentum of a system of objects is conserved when there is no net force on the system.
HS-PS1-6: Refine the design of a chemical system by specifying a change in conditions that would produce increased amounts of products at equilibrium.
HS-PS1-7: Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.