Chemistry Section 10.1: Acid-Base Theory

Questions and Answers

What characterizes an Arrhenius acid?

It produces hydrogen ions in solution. (correct)

It is a molecular compound that does not ionize.

It produces hydroxide ions in solution.

It donates a hydrogen ion to another substance.

How does an Arrhenius base differ from an Arrhenius acid?

An Arrhenius base accepts hydrogen ions; an acid does not.

An Arrhenius base produces hydrogen ions; an acid does not.

An Arrhenius base does not dissociate in water.

An Arrhenius base produces hydroxide ions; an acid does not. (correct)

What is ionization according to Arrhenius theory?

Production of only positive ions from a compound.

Release of ions from an ionic compound.

Production of individual ions from a dissolved molecular compound. (correct)

Formation of hydrogen ions from water.

What process is described as dissociation in the context of Arrhenius bases?

Release of ions from a solid ionic substance. Signup and view all the answers

Which of the following statements is true regarding an Arrhenius acid?

It produces hydrogen ions when dissolved in water. Signup and view all the answers

Which option describes the overall role of an Arrhenius base in a neutralization reaction?

It produces hydroxide ions to neutralize acids. Signup and view all the answers

In the context of Arrhenius theory, what makes acids and bases unique?

Acids produce hydrogen ions and bases produce hydroxide ions. Signup and view all the answers

What defines the ionization process in Arrhenius acids?

Separation of molecular compounds into ions. Signup and view all the answers

Which statement correctly defines an acid and a base?

An acid donates a hydrogen ion, and a base produces hydroxide ions. Signup and view all the answers

In the Brønsted–Lowry acid-base theory, what happens in the reaction HF(aq) + H2O(l) ⇌ H3O+(aq) + F–(aq)?

HF is the acid and H3O+ is the conjugate acid. Signup and view all the answers

Which of the following is an example of an amphiprotic substance?

H2O Signup and view all the answers

What characterizes a monoprotic acid?

It supplies one proton (H+ ion) per molecule. Signup and view all the answers

Which of the following pairs represents a conjugate acid-base pair in the given reaction: HF(aq) + H2O(l) ⇌ H3O+(aq) + F–(aq)?

H2O(l) and H3O+(aq) Signup and view all the answers

What is the role of a base in an acid-base reaction according to the Brønsted–Lowry theory?

To accept a hydrogen ion. Signup and view all the answers

During the dissociation of a diprotic acid, what can be inferred if one mole of the acid can donate two protons?

It is classified as a diprotic acid. Signup and view all the answers

Which of the following identifies a fundamental property of acids in water?

They produce hydrogen ions. Signup and view all the answers

What is the pKa of a solution with a Ka of 6.3 x 10–4?

3.20 Signup and view all the answers

Which statement correctly describes the nature of buffers?

Buffers can resist changes in pH upon adding small amounts of acid or base. Signup and view all the answers

What happens when a base is added to a buffer solution?

It reacts with H3O+ ions producing water. Signup and view all the answers

What is a major component of a buffer system?

A weak acid and its conjugate base. Signup and view all the answers

What occurs when excess H3O+ ions are introduced to a buffer solution?

The equilibrium shifts to the left consuming H3O+ ions. Signup and view all the answers

Which of the following best describes a buffer's ability to respond to added acid or base?

It maintains a relatively stable pH despite small additions. Signup and view all the answers

Which active species in a buffer reacts with added acids?

A conjugate base. Signup and view all the answers

What is the primary function of a buffer solution in a chemical context?

To prevent significant changes in pH. Signup and view all the answers

What characterizes a diprotic acid?

It supplies two protons per molecule. Signup and view all the answers

Which statement is true regarding triprotic acids?

They supply three protons per molecule. Signup and view all the answers

How are polyprotic acids defined?

Acids that supply two or more protons. Signup and view all the answers

What distinguishes a monoprotic acid from diprotic and triprotic acids?

It supplies one proton per molecule. Signup and view all the answers

Which of the following correctly describes the differences between monoprotic, diprotic, and triprotic acids?

Monoprotic acids supply one proton; diprotic acids supply two; triprotic acids supply three. Signup and view all the answers

Why can't diprotic and triprotic acids be considered monoprotic?

They supply multiple protons upon dissolution. Signup and view all the answers

Which of the following represents an incorrect definition related to acid types?

A triprotic acid only supplies one proton. Signup and view all the answers

What is the significance of protons (H+ ions) in the context of acids?

The number of protons released determines the type of acid. Signup and view all the answers

What defines an Arrhenius acid?

A substance that produces hydrogen ions in water Signup and view all the answers

What defines a Brønsted–Lowry base?

A substance that accepts a hydrogen ion Signup and view all the answers

Which statement describes both Arrhenius and Brønsted–Lowry definitions of acids?

Both produce hydrogen ions Signup and view all the answers

Which of the following is NOT a characteristic of an Arrhenius base?

Accepts hydrogen ions Signup and view all the answers

What is required for a substance to act as a Bronsted–Lowry acid?

It must donate a hydrogen ion Signup and view all the answers

What describes the fundamental difference between Arrhenius and Brønsted–Lowry definitions of bases?

Arrhenius bases produce hydroxide ions, while Brønsted–Lowry bases accept protons. Signup and view all the answers

Which option correctly describes the role of a hydrogen ion in acid-base reactions?

It can be donated or accepted in different acid-base theories. Signup and view all the answers

How do the definitions of acid and base differ under Arrhenius and Brønsted–Lowry theories?

Arrhenius bases produce hydroxide ions, while Brønsted–Lowry bases accept hydrogen ions. Signup and view all the answers

Study Notes

Arrhenius Acid–Base Theory

An Arrhenius acid releases H+ ions in solution (e.g., HNO3 → H+ + NO3–).
An Arrhenius base releases OH– ions in solution (e.g., NaOH → Na+ + OH–).
Ionization refers to forming ions from a molecular compound in solution.
Dissociation refers to the release of ions from an ionic compound in solution.

Brønsted–Lowry Theory

Brønsted–Lowry acid: a substance that donates a proton (H+).
Brønsted–Lowry base: a substance that accepts a proton (H+).
Conjugate acid-base pairs arise when an acid donates a proton and the base accepts it (e.g., HF and F–).
Amphiprotic substances can act as both an acid and a base (e.g., H2O).

Mono-, Di-, and Triprotic Acids

Monoprotic acid: supplies one proton (H+) per molecule (e.g., HCl).
Diprotic acid: supplies two protons (e.g., H2SO4).
Triprotic acid: supplies three protons (e.g., H3PO4).
Polyprotic acids include both diprotic and triprotic acids.

Acid Strength and pKa

pKa expresses acid strength, defined as pKa = –log Ka.
A lower pKa value indicates a stronger acid.
For Ka = 6.3 x 10–4, pKa is approximately 3.20, indicating the solution is acidic.

Buffers

Buffers resist pH changes upon the addition of small amounts of acid or base.
A typical buffer system consists of a weak acid and its conjugate base.
Buffers operate by reacting with added acids or bases:
- When OH– is added, it reacts with H3O+, shifting equilibrium to produce more H3O+.
- When H3O+ is added, the system neutralizes excess H3O+, maintaining pH stability.

Electrolytes and Titrations

Electrolytes are substances that dissociate into ions in solution, conducting electricity.
Acid-base titrations involve the gradual addition of an acid or base to determine the concentration of a solution.
Understanding equivalents and milliequivalents is crucial for measurements in titrations.

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Description

This quiz covers the fundamentals of Arrhenius acid-base theory, defining what constitutes an Arrhenius acid and base. Test your understanding of how acids and bases behave in water and their roles in chemical reactions. Perfect for students studying general chemistry concepts.