Formation of Ions from Acids & Bases

Questions and Answers

What defines an acid according to the Arrhenius theory?

An acid is defined as a substance that dissociates in aqueous solution to give H+ ions.

How do strong acids differ from weak acids in terms of dissociation?

Strong acids dissociate almost completely, while weak acids dissociate partially.

According to the Lowry-Bronsted theory, what roles do acids and bases play?

Acids are proton donors, while bases are proton acceptors.

Describe the formation of hydronium ions from an acid in solution.

A proton from the acid adds to a water molecule, forming H3O+ (hydronium ion). Signup and view all the answers

What role do lone pairs of electrons play in the formation of H3O+?

The lone pair of electrons on the oxygen atom of water forms a coordinate covalent bond with the H+ ion. Signup and view all the answers

Explain why the oxygen atom in water has a slight negative charge.

Oxygen has a higher electronegativity than hydrogen, causing a charge separation. Signup and view all the answers

How is the hydroxyl ion (OH-) formed from ammonia in aqueous solution?

The H+ ion from water adds to the lone pair of electrons on the nitrogen atom of ammonia, producing OH-. Signup and view all the answers

What is the significance of the coordinate covalent bond in these ion formations?

The coordinate covalent bond is crucial for the interaction between H+ ions and the electron pairs in water or ammonia. Signup and view all the answers

Describe the charge distribution of a water molecule.

The hydrogen atoms carry a slight positive charge, while the oxygen atom carries a slight negative charge. Signup and view all the answers

What happens to the H+ ion during the formation of ammonium ion from ammonia?

The H+ ion adds to the lone pair of electrons on the nitrogen atom, forming NH4+ (ammonium ion). Signup and view all the answers

Study Notes

Arrhenius Theory

Acids dissociate in aqueous solutions to release H+ ions.
Strong acids dissociate almost entirely, while weak acids only partially dissociate.

Lowry-Bronsted Theory

Defines acids as proton donors and bases as proton acceptors, recognizing protons as H+ ions.

Hydronium Ions (H3O+)

Formed when acids dissolve in aqueous solutions.
The water molecule is polar, with a slight positive charge on hydrogen and a slight negative charge on oxygen.
Oxygen in water possesses two lone pairs of electrons that are not shared.

Formation of Hydronium Ion

HCl (an acid) reacts with water:
- HCl + H2O → H3O+ + Cl-
A proton (H+) released from the acid binds to oxygen's lone pair, forming a coordinate covalent bond.

Hydroxyl Ions (OH−)

Formed from alkalis, like ammonia (NH3), in aqueous solution.

Ammonia Molecule

Ammonia can react with water to form hydroxyl ions:
- NH3 + H2O → NH4OH → OH− + NH4+
A proton from water adds to the nitrogen atom's lone pair, forming a coordinate covalent bond.

Ammonium Ion (NH4+)

Formed during the reaction when NH3 accepts a proton.
Ammonia is a polar covalent molecule due to significant electronegativity differences between nitrogen and hydrogen atoms.

Description

This quiz covers the formation of hydronium and hydroxyl ions from acids and alkalis, focusing on the Arrhenius and Lowry-Brønsted theories. Understand the dissociation of strong and weak acids, as well as the role of water molecules in these processes.