Acids and bases Flashcards
Define acids (Arrhenius’ theory)
An acid produces H⁺ ions in water.
Example of an acid HCl ⇾
H⁺ + Cl-
What did Arrhenius’ theory allow?
The existence of independent H⁺ ions.
Arrhenius’ theory allowed the existence of independent H⁺ ions. Has this theory been proven true or false?
False
What does the H⁺ ion react with and what is formed?
- React with water
- Forms H₃O⁺
What is H₃O⁺ known as?
Oxonium ion / hydronium ion
Were non-polar organic solvents included in Arrhenius’ theory?
No
Define base (Arrhenius’ theory)
A base produces OH- ions in water.
What is an alkali?
A base that is soluble in water.
Example of a base NaOH ⇾
Na⁺ + OH-
Example of a base Mg(OH)₂ ⇾
Mg₂⁺ + 2OH-
Is NaOH an alkali?
Yes
Is Mg(OH)₂ an alkali?
No
State a problem with Arrhenius’ theory.
Arrhenius’ theory of bases excluded common bases such as NH₃.
Give the general equation for acids dissociating in solution (where HA is an acid).
HA + H₂O ⇾ A- + H₃O⁺
Define monobasic acids.
A monobasic acid produces one H⁺ ion in solution. e.g. HCl and HNO₃.
Define dibasic acids
A dibasic acid produces two H⁺ ions in solution e.g. H₂SO₄.
Define tribasic acids
A tribasic acid produces three H⁺ ions in solution e.g. H₃PO₄.
Who put forward a newer definition?
Bronsted-Lowry
Define acid (Bronsted-Lowry theory)
An acid is a proton (H⁺) donor.
Define base (Bronsted-Lowry theory)
A base is a proton (H⁺) acceptor.
What is the acid and base in : HCl + H₂O ⇾ Cl- + H₃O⁺
Base - H₂O
Acid - HCl
What is the acid and base in : NH₃ + H₂O ⇾ NH₄⁺ + OH-
Base - NH₃
Acid - H₂O
What is water as it can act as both an acid and a base?
Amphoteric
Define amphoteric
A substance that can act as both an acid and a base.
What is the acid and what is the base : H₂O + H₂O ⇾ H₃O⁺ + OH-
1st H₂O - Acid
2nd H₂O - Base
An acid only acts as an acid in the ……………
Presence of a base.
Define conjugate pairs
Two substances that differ by one proton.
Define conjugate acid
A base plus a H⁺ ion.
Define conjugate base
An acid minus a H⁺ ion.
Give three examples of conjugate pairs with HCl, HNO₃ and NH₃.
HCl / Cl-
HNO₃ / NO₃-
NH₃ / NH₄⁺
Why is HCl / Cl- a conjugate pair?
As they differ by only one proton.
Pick out the acid, base, conjugate acid and conjugate base form the following equation : H₂SO₄ + H₂O ⇾ H₃O⁺ + HSO₄-
Acid - H₂SO₄
Base - H₂O
Conjugate acid - H₃O⁺
Conjugate base - HSO₄-
Loser (just to understand)
Acid
Gainer (just to understand)
Base
If the question is looking for the conjugate acid, what must the substances in the questions be?
Bases
If the question is looking for the conjugate acid then the substances in the question must be bases so ……
Accept a proton onto each to get the answer
If the question is looking for the conjugate base, what must the substances in the questions be?
Acids
If the question is looking for the conjugate acid then the substances in the question must be acids so ……
Donate a proton from each to get the answer.
What happens to acids when they are placed in solutions?
They split up into their ions, hydrogens ions and anions.
What does the anion produced in a solution depend on?
The acid involved
When acids are placed in solutions they split up into their ions, hydrogen ions and anions. What is this known as?
Dissociation
What does the number of dissociation depend on?
Whether the acids are monobasic, dibasic or tribasic.
How many equations do monobasic acids have for their dissociation?
One