15 Questions
What did the Arrhenius theory propose about acids?
Acids can only exist in aqueous solutions.
According to the Bronsted-Lowry theory, what defines an acid?
A substance that can donate a proton.
Which scientist proposed the Bronsted-Lowry theory of acids and bases?
Johannes Bronsted and Thomas Lowry
What does the Bronsted-Lowry theory say about bases?
Bases are substances that accept protons.
In the reaction: HCl + H2O → H3O+ + Cl-, what role does HCl play?
Bronsted-Lowry acid
What is the chemical formula for ammonia?
NH3
Which theory allowed for substances to act both as acids and bases depending on the circumstance?
Bronsted-Lowry theory
What does the Bronsted-Lowry theory define an acid as?
Proton donor
In the Lewis theory, what is a Lewis acid?
A substance that accepts an electron pair to form a covalent bond
What happens when ammonia (NH3) dissolves in water based on the text?
Water donates a proton to ammonia
Which ion is considered a Lewis acid in the given text?
Silver ion (Ag+)
What is formed when silver ion (Ag+) accepts electron pairs from ammonia according to the Lewis theory?
(Ag(NH3 )2 )+
In the Bronsted-Lowry theory, what is a base defined as?
Proton acceptor
What can be considered as a Lewis base?
Substance that donates an electron pair
What differentiates Lewis acids from Arrhenius acids?
Lewis acids must be dissolved in water
Study Notes
Arrhenius Acid and Base
- Proposed by Svante Arrhenius in 1887
- An acid is a substance that can give away a hydrogen atom in the form of an ion (H+) when dissolved in water, producing an aqueous acid
- Limitations: only applicable to aqueous solutions, does not account for acids in gaseous form, and substances that can act as both acids and bases
Bronsted-Lowry Acid and Base
- Proposed by Johannes Bronsted and Thomas Lowry in 1923
- An acid is a substance that can donate a proton (hydrogen atom that has lost its electron to become a positively charged ion of H+)
- A base is a substance that accepts protons
- Examples:
- Hydrogen chloride (HCl) dissolving in water, donating a proton to form H3O+ and Cl-
- Ammonia (NH3) accepting a proton from water to form NH4+ and OH-
Conjugate Acids and Bases
- Conjugate acid: an acid that forms when a base gains a proton
- Conjugate base: a base that forms when an acid loses a proton
- Every Bronsted-Lowry acid has a conjugate base, and every Bronsted-Lowry base has a conjugate acid
Lewis Acid and Base
- Proposed by G.N. Lewis in 1923
- An acid is a substance that accepts an electron pair to form a covalent bond
- A base is a substance that donates an electron pair to form a covalent bond
- Examples:
- Silver ion (Ag+) accepting electron pairs from ammonia to form a covalent bond
- Anion donating a pair of electrons to form a covalent bond
Key Points
- All Arrhenius acids and bases are also Bronsted-Lowry acids and bases, but not the opposite
- Bronsted-Lowry acid-base theory is more comprehensive and applicable to a wider range of substances
- Lewis acid-base theory is broader and encompasses substances that don't contain hydrogen at all
Learn about Johannes Bronsted and Thomas Lowry who developed the Bronsted-Lowry theory of acids and bases as an alternative to the Arrhenius theory. Explore how their theory expands the definition of acids and bases beyond aqueous solutions.
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