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pH and Protein Solubility—A Reversible Demonstration Kit

By:The Flinn Staff

Item #: AP6692 

Price: $23.50

In Stock.

In the pH and Protein Solubility Reversible Demonstration Kit for biochemistry, demonstrate the properties of proteins and the effect of pH on protein solubility with this colorful and reversible activity.

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Product Details

Demonstrate the properties of proteins and the effect of pH on protein solubility with this colorful and reversible activity. Proteins contain many acidic and basic groups that have different structures at different pH values. When acids and bases are added to a protein solution, the solubility of the protein changes drastically. This demonstration looks at the acid–base and solubility properties of casein, the main protein in milk. The structure of the protein at different pH values is discussed. Teacher Demonstration Notes included.

Concepts: Proteins, isoelectric point, solubility, pH.
Time Required: 15 minutes


Materials Included in Kit: 
Casein, 7 g
Hydrochloric acid solution, 2 M, 100 mL
Sodium hydroxide solution, 0.1 M, 250 mL
Sodium hydroxide solution, 2 M, 75 mL
Universal indicator solution, 20 mL
Pipet, Beral-type, graduated, 14

Correlation to Next Generation Science Standards (NGSS)

Science & Engineering Practices

Analyzing and interpreting data
Planning and carrying out investigations
Constructing explanations and designing solutions

Disciplinary Core Ideas

MS-PS1.A: Structure and Properties of Matter
MS-PS1.B: Chemical Reactions
HS-PS1.A: Structure and Properties of Matter
HS-PS1.B: Chemical Reactions
HS-PS2.B: Types of Interactions
HS-LS1.A: Structure and Function
HS-LS1.C: Organization for Matter and Energy Flow in Organisms

Crosscutting Concepts

Energy and matter
Structure and function

Performance Expectations

MS-PS2-2: Plan an investigation to provide evidence that the change in an object’s motion depends on the sum of the forces on the object and the mass of the object
MS-PS3-2: Develop a model to describe that when the arrangement of objects interacting at a distance changes, different amounts of potential energy are stored in the system.
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-PS2-4: Use mathematical representations of Newton’s Law of Gravitation and Coulomb’s Law to describe and predict the gravitational and electrostatic forces between objects.
HS-PS3-1: Create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other component(s) and energy flows in and out of the system are known.
HS-PS3-2: Develop and use models to illustrate that energy at the macroscopic scale can be accounted for as a combination of energy associated with the motion of particles (objects) and energy associated with the relative position of particles (objects).