LESSON 1: ACIDS AND BASES

citric acid

acid contain in citrus fruits

base

is baking soda base or acid?

True – Svante Arrhenius, a Swedish chemist, proposed the theory.

T or F

The Arrhenius theory was proposed by Svante Arrhenius, a Swedish chemist.

T or F

According to the Arrhenius theory, strong electrolytes exist partly as ions and partly as molecules in aqueous solutions.

T or F

Acids, according to Arrhenius, dissociate in water to form hydrogen ions (H+).

T or F
Bases, according to Arrhenius, dissociate in water to form hydroxide ions (OH–).

T or F
The Arrhenius theory applies to all acids and bases, even those that do not produce H+ or OH– ions.

T or F

The Arrhenius theory can only be applied to aqueous solutions.

T OR F

The Arrhenius theory successfully explains the behavior of ammonia (NH3) as a base.

T OR F

The Arrhenius theory only describes the relationship between H+ and OH– ions in water.

T OR F
One limitation of the Arrhenius theory is that it does not explain acids and bases in non-aqueous solutions.

T OR F

Arrhenius acids and bases must always be in a liquid state to dissociate into ions.

b) Svante Arrhenius

Who proposed the Arrhenius theory of acids and bases?
a) Robert Boyle
b) Svante Arrhenius
c) Antoine Lavoisier
d) Dmitri Mendeleev

b) H+

According to the Arrhenius theory, acids release which ion in water?
a) OH–
b) H+
c) Na+
d) Cl–

b) OH–

Arrhenius bases release which ion in water?
a) H+
b) OH–
c) NO3–
d) CO3^2–

c) It does not explain acids and bases in non-aqueous solutions.

What is a key limitation of the Arrhenius theory?
a) It applies only to non-aqueous solutions.
b) It includes bases that do not produce hydroxide ions.
c) It does not explain acids and bases in non-aqueous solutions.
d) It defines acids as substances that donate protons.

c) NH3 – Ammonia does not release OH– ions directly.

Which of the following is not an example of an Arrhenius base?
a) NaOH
b) KOH
c) NH3
d) Ca(OH)2

b) They exist only as ions in aqueous solutions.

What does the Arrhenius theory say about strong electrolytes?
a) They exist only in molecular form in aqueous solutions.
b) They exist only as ions in aqueous solutions.
c) They exist partly as ions and partly as molecules in aqueous solutions.
d) They do not dissociate at all in water.

a) Acids increase the concentration of H+ ions in water.

Which of the following statements is true according to the Arrhenius theory?
a) Acids increase the concentration of H+ ions in water.
b) Bases decrease the concentration of OH– ions in water.
c) Acids must contain OH– to be classified as Arrhenius acids.
d) Bases cannot be soluble in water.

a) It does not release hydroxide ions (OH–) in water.

Why does ammonia (NH3) not fit the Arrhenius definition of a base?
a) It does not release hydroxide ions (OH–) in water.
b) It does not dissolve in water.
c) It does not increase the concentration of H+ ions.
d) It is an acid, not a base.

b) HCl – Hydrochloric acid dissociates in water to release H+.

According to Arrhenius, which of the following is an acid?
a) NaOH
b) HCl
c) NH3
d) KOH

c) Ammonia (NH3) is an Arrhenius base. – This is false because NH3 does not directly produce OH– ions.

Which of the following statements about Arrhenius acids and bases is false?
a) Arrhenius bases dissociate in water to produce OH– ions.
b) The theory applies only to aqueous solutions.
c) Ammonia (NH3) is an Arrhenius base.
d) The Arrhenius theory does not explain acid-base behavior in non-aqueous solutions.

True – Johannes Bronsted and Thomas Lowry proposed the existence of the hydronium ion (H₃O⁺).

T OR F
Johannes Bronsted and Thomas Lowry proposed the existence of the hydronium ion (H₃O⁺).

False – The Bronsted-Lowry theory is more general than the Arrhenius theory.

T OR F

• The Bronsted-Lowry theory is less general than the Arrhenius theory.

True – Acids donate protons in the Bronsted-Lowry theory.

T OR F

According to the Bronsted-Lowry theory, acids donate protons.

False – Bases accept protons, not donate them

T OR F

According to the Bronsted-Lowry theory, bases donate protons.

True – Water donates a hydrogen ion to ammonia, making ammonia a base.

T OR F

• Water donates a hydrogen ion to ammonia, making ammonia a base.

True – NH₃ accepts a proton to form an ammonium ion (NH₄⁺).

T OR F

NH₃ accepts a proton to form an ammonium ion (NH₄⁺).

True – The pair of species in the reactants and products that differ by one proton are called conjugates.

T OR F

The pair of species in the reactants and products that differ by one proton are called conjugates.

False – Every acid has a conjugate base formed by removing a proton.

T OR F

Every acid has a conjugate base formed by adding a proton.

• False – Every base has a conjugate acid formed by adding a proton.

T OR F

Every base has a conjugate acid formed by removing a proton.

True – Water can act as both a Bronsted-Lowry acid and a Bronsted-Lowry base (amphoteric nature)

T OR F

Water can act as both a Bronsted-Lowry acid and a Bronsted-Lowry base.

False – The autoionization of water means water can act as both an acid and a base.

T OR F

The autoionization of water means that water only acts as an acid.

False – In the presence of an acid, water acts as a proton acceptor (base).

T OR F

In the presence of an acid, water acts as a proton donor.

True – In the presence of a base, water acts as a proton donor (acid).

T OR F

In the presence of a base, water acts as a proton donor

True – The ion product constant (Kw) remains unchanged because very little water ionizes.

T OR F

The ion product constant (Kw) of water remains unchanged because very little water ionizes.

False – The Bronsted-Lowry theory has limitations, such as not fully addressing the autoionization of water.

T OR F

The Bronsted-Lowry theory completely replaces the Arrhenius theory without limitations.

Johannes Bronsted and Thomas Lowry

Who are the two scientists who proposed the Bronsted-Lowry theory?

Hydronium ion (H₃O⁺)

What ion's existence did the Bronsted-Lowry theory suggest?

It provides a more general definition of acids and bases than Arrhenius’ theory.

What does the Bronsted-Lowry theory address that the Arrhenius theory could not?

Conjugate acid-base pair

What is the term for a pair of species that differ by only one proton?

A proton donor

According to the Bronsted-Lowry theory, what is an acid?

A proton acceptor

According to the Bronsted-Lowry theory, what is a base?

Ammonium ion (NH₄⁺)

What ion is formed when NH₃ accepts a proton?

Amphoteric

What term describes water’s ability to act as both an acid and a base?

Proton acceptor (base)

In the presence of an acid, what role does water play?

Proton donor (acid)

In the presence of a base, what role does water play?

Ion Product Constant (Kw)

what is the equilibrium constant for the ionization of water called?

The concentration of water (H₂O)

What remains almost unchanged due to the very small ionization of water?

A conjugate base

What does every acid have that is formed by removing a proton?

A conjugate acid

What does every base have that is formed by adding a proton?

Bronsted-Lowry theory

What theory expands on Arrhenius’ acid-base definition by considering proton exchange?

True – Gilbert Lewis proposed the Lewis Theory of acids and bases

T OR F

Gilbert Lewis proposed the Lewis Theory of acids and bases.

False – The Lewis theory applies to both aqueous and non-aqueous solutions.

T OR F

The Lewis theory only applies to aqueous solutions

False – The Lewis theory focuses on the transfer of electrons, not protons.

T OR F

The Lewis theory focuses on the transfer of protons rather than electrons.

True – Lewis acids are electron-pair acceptors.

T OR F

Lewis acids are electron-pair acceptors.

False – Lewis bases donate electron pairs, not protons.

T OR F

Lewis bases donate protons to form bonds.

True – Metal cations (Mn⁺) and boron are common Lewis acids.

T OR F

Metal cations (Mn⁺) and boron are common examples of Lewis acids.

True – Lewis bases donate electron pairs.

T OR F

Lewis bases are electron-pair donors.

True – Species with O, N, or halogens frequently have lone pairs, making them Lewis bases.

T OR F

Species with oxygen (O), nitrogen (N), or halogens frequently act as Lewis bases due to their lone pairs.

False – The Lewis theory can be extended to Arrhenius and Bronsted-Lowry theories, showing they are related.

T OR F

The Lewis theory is unrelated to the Arrhenius and Bronsted-Lowry theories.

True – The Lewis theory is more general and applies beyond hydrogen ions.

T OR F

The Lewis theory is more general and can be applied beyond hydrogen ions.

d) Gilbert Lewis – He developed the Lewis theory.

Who proposed the Lewis Theory?
a) Svante Arrhenius
b) Johannes Bronsted
c) Thomas Lowry
d) Gilbert Lewis

b) It focuses on electron pair transfer. – The theory is based on the movement of electrons, not protons.

What is a key feature of the Lewis theory?
a) It focuses on hydrogen ion transfer.
b) It focuses on electron pair transfer.
c) It only applies to aqueous solutions.
d) It states that acids and bases are always ionic compounds.

b) An electron-pair acceptor. – Lewis acids accept electron pairs.

What is a Lewis acid?
a) A proton donor
b) An electron-pair acceptor
c) A species that releases hydroxide ions
d) A negatively charged ion

c) A species that donates electron pairs. – Lewis bases donate electron pairs.

Which of the following is a Lewis base?
a) A species that donates protons
b) A species that accepts electron pairs
c) A species that donates electron pairs
d) A species that releases hydrogen gas

b) It includes non-aqueous solutions. – Unlike Arrhenius and Bronsted-Lowry theories, Lewis theory applies beyond water-based reactions.

Why is the Lewis theory considered more general than other acid-base theories?
a) It only applies to strong acids and bases.
b) It includes non-aqueous solutions.
c) It only applies to reactions involving water.
d) It ignores electron-pair interactions.