Ch.17 - Acids and Bases

Problem 37

Chapter 17, Problem 37

Both H₂O and H₂PO₄^– are amphoteric. Write an equation to show how each substance can act as an acid and another equation to show how each can act as a base.

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Identify the concept of amphoteric substances: Amphoteric substances can act as either an acid or a base depending on the reaction they are involved in.

For H2O acting as an acid: Write the equation where H2O donates a proton (H+) to a base, for example, NH3, forming OH- and NH4+.

For H2O acting as a base: Write the equation where H2O accepts a proton from an acid, such as HCl, forming H3O+ and Cl-.

For H2PO4- acting as an acid: Write the equation where H2PO4- donates a proton to a base, such as OH-, forming HPO4^2- and H2O.

For H2PO4- acting as a base: Write the equation where H2PO4- accepts a proton from an acid, such as H3O+, forming H3PO4 and H2O.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Amphoteric Substances

Amphoteric substances are compounds that can act as both acids and bases depending on the reaction context. This dual behavior allows them to either donate protons (H+) in acidic reactions or accept protons in basic reactions. Understanding this property is crucial for predicting the behavior of substances like H2O and H2PO4- in various chemical environments.

Acid-Base Reactions

Acid-base reactions involve the transfer of protons between reactants. An acid is defined as a proton donor, while a base is a proton acceptor. The Brønsted-Lowry theory is commonly used to describe these reactions, where the acid-base interaction can be represented through chemical equations that illustrate the transfer of H+ ions.

Chemical Equations

Chemical equations are symbolic representations of chemical reactions, showing the reactants and products involved. For amphoteric substances, writing equations that depict their behavior as acids and bases requires an understanding of how to balance the equations and represent the proton transfer accurately. This skill is essential for illustrating the dual nature of compounds like H2O and H2PO4-.

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Textbook Question

Write the formula for the conjugate base of each acid. b. HBr

Textbook Question

Write the formula for the conjugate base of each acid. c. HI

Textbook Question

Write the formula for the conjugate base of each acid. d. HCHO2

Textbook Question

Classify each acid as strong or weak. If the acid is weak, write an expression for the acid ionization constant (K_a). a. HNO₃

Textbook Question

Classify each acid as strong or weak. If the acid is weak, write an expression for the acid ionization constant (K_a). b. HCl

Textbook Question

Classify each acid as strong or weak. If the acid is weak, write an expression for the acid ionization constant (K_a). c. HBr

Both H2O and H2PO4– are amphoteric. Write an equation to show how each substance can act as an acid and another equation to show how each can act as a base.

Verified video answer for a similar problem:

Key Concepts

Amphoteric Substances

Acid-Base Reactions

Chemical Equations

Both H₂O and H₂PO₄^– are amphoteric. Write an equation to show how each substance can act as an acid and another equation to show how each can act as a base.