Chapter 12 acid and bases

An Arrhenius acid

Dissociates in water to produce H ions

Monobasic acid

HCL Each molecule dissociates to produce one h ions

Diabasic aid

H2so4 each molecule dissociates to produce 2 h ions

Tribasic acid

H3PO4 each molecule dissociates to produce 3 h ions

The dissociation of an acid HA

HA + H20 ←→ A- + H3O+

An Arrhenius base is

A substance that dissociates in water to produce OH- ions

Alkali

A base dissolved in water

Monobasic base

NaOH each molecule dissociates to produce one OH- ions

Dibasic base

Ca(OH)2 each molecule dissociates to produce two OH- ions

Tribasic base

Al(OH3) each molecule dissociates to produce three OH- ions

A Bronsted-Lowry acid

Is a proton donor (loses a proton)

Brønsted-Lowry base

Is a proton acceptor (takes in a proton)

Amphoteric substance

Can act as either an acid or a base eg water

Differences between Arrhenius and Brønsted-Lowry

Arrhenius theory is limited to aqueous solutions

Substances such as NH3 would not be classified as a base under Arrhenius but would under Brønsted-Lowry

Arrhenius theory cannot explain how a substance can be amphoteric

Strong acids

Hydrochloric acid (HCL)

Sulfric acid (H2SO4)

Nitric acid (HNO3)

Weak acid

Ethanoic acid (CH3COOH)

Strong base

Sodium hydroxide (NaOH)

Potassium hydroxide (KOH)

Calcium hydroxide (Ca(OH)2) (limewater)

Weak base

Sodium carbonate (Na2CO3)

Ammonium hydroxide (NH4OH)

A conjugate acid

Is the substance formed when a base accepts a proton.

You are being shown a base, make it accept a proton to get the conjugate and

A conjugate base

Is the substance formed when an acid donates a proton

You are being shown an acid, remove a proton from it to get the conjugate base

The stronger the acid

The weaker the conjugate base

The weaker the acid

The stronger the conjugate base

A conjugate acid-base pair

Is an acid and base that differ by one proton

A salt

Is formed when the H ion of acid is replaced by a metal ion or ammonium ion

Neutralisation

Is the reaction between an acid and a base to form a salt and water

Example of neutralisation

Indigestion tablets are alkalis which are taken to neutralise excess stomach

Lime (CaO) is an alkali spread on soil to neutralise the acidity of the soil allowing plants to grow

Vinegar is an acid which will neutralise the alkali sting of Warks

Household examples of acids

Ethanoic acid in vinegar

Citric acid in lemons and grapes

Household examples of bases

Sodium hydroxide in caustic soda in oven cleaners

Magnesium hydroxide in milk of magnesia of indigestion and constipation