Reactivity 3.1—Proton transfer reactions SL Flashcards
What defines a Brønsted–Lowry acid?
A Brønsted–Lowry acid is defined as a substance that donates a proton (H+) in a reaction. It is known as a proton donor.
What defines a Brønsted–Lowry base?
A Brønsted–Lowry base is defined as a substance that accepts a proton (H+) in a reaction. It is known as a proton acceptor.
How is a hydrogen ion (H+) represented in aqueous solutions?
In aqueous solutions, a hydrogen ion (H+) is often represented as a hydronium ion (H3O+).
In the reaction between hydrogen chloride gas and water, which is the Brønsted–Lowry acid, and which is the base?
In the reaction between hydrogen chloride gas and water, hydrogen chloride (HCl) is the Brønsted–Lowry acid because it donates a proton, and water (H2O) is the Brønsted–Lowry base because it accepts a proton.
What must all Brønsted–Lowry acids contain?
All Brønsted–Lowry acids must contain hydrogen, as they need to be able to donate a hydrogen ion to another species.
What is the conjugate acid of NH3?
NH4+ (The ammonium ion is the conjugate acid of ammonia, as it has gained a proton.)
How does water act as an amphiprotic species with NH3?
Water donates a proton to NH3, acting as an acid. NH3 + H2O ⇌ NH4+ + OH−.
Conjugate acid
Has one more proton than the base.
Conjugate base
Has one less proton than the acid.
Is water (H2O) capable of acting as both an acid and a base? Give an example reaction where it acts as a base.
Yes, water is amphiprotic. As a base, it can accept a proton from HCl: HCl + H2O ⇌ Cl− + H3O+.
Ionic product of water.
The ionic product of water is the product of the [H^+] and [OH^−] in water at a particular temperature.
Kw=[H+][OH−]
Name two common acid-base indicators
Litmus paper and Universal indicator
What’s the main difference between Litmus paper and Universal indicator?
Litmus paper cannot determine the pH value unlike the universal indicator
What distinguishes strong acids/bases from weak acids/bases in aqueous solutions?
Strong acids/bases completely dissociate/ionise in solution, while weak acids/bases only partially dissociate/ionise.
Name three common strong acids
Hydrochloric acid, sulfuric acid, and nitric acid
What are examples of weak acids
Ethanoic acid and carbonic acid
What characterizes weak bases
Weak bases partially dissociate in water
How do the pH and electrical conductivity differ between strong and weak acids?
Strong acids have a lower pH and higher electrical conductivity compared to weak acids at the same concentration.
How do the strengths of conjugate acids and bases compare between strong and weak acids?
Strong acids have relatively weak conjugate bases, while weak acids have relatively strong conjugate bases.
What are neutralisation reactions?
Reactions where an acid reacts with a base, moving the pH towards neutral.
Reaction of acids with metal hydroxides produces?
Salt and water.
How can you test for carbon dioxide in reactions involving acids and carbonates?
By bubbling the gas through limewater; if CO₂ is present, the limewater turns milky due to calcium carbonate formation.
How do acids react with ammonia and amines?
They undergo neutralisation reactions to produce a salt.
What is titration used for?
To determine the unknown concentration of an acid or base by using a solution of known concentration.
What signifies the equivalence point in a titration?
It is the point where the acid and base have been reacted in stoichiometrically equivalent amounts, typically indicated by a color change of an indicator.
Describe the pH change in a neutralisation reaction between a strong acid and a strong base.
The pH decreases from a high value to a lower value as the concentration of H⁺ ions increases.
What is the significance of the equivalence point on a pH curve?
It indicates the volume at which the acid and base have reacted completely, resulting in a solution containing only salt and water.
What is the typical pH at the equivalence point for a titration between a strong acid and a strong base?
The pH at the equivalence point is typically around 7.
