AcidsAcids contain hydrogen ions Arrhenius Definition BasesBases contain hydroxide ions (OH - ) Savante Arrhenius, Swedish chemist who by 1890 formulated the first useful theory for acids.
Bronsted-Lowry Definition AcidsAcids are proton (H + ) donors. BasesBases are proton (H + ) acceptors. Conjugate acid-base pairs are formed.
HCl + H 2 O Cl – + H 3 O + conjugate acid conjugate base baseacid Bronsted-Lowry Definition Pairs identifies the particles formed when H+ ions are donated and accepted when an acid or a base is dissolved in water. Base gains H+ conjugate acid formed Particle that remains conjugate base
Strength Strong Acid/Base Strong Acid/Base – 100% ionized in water – many ions produced – strong electrolyte - + HCl HNO 3 H 2 SO 4 HBr HI HClO 4 NaOH KOH Ca(OH) 2 Ba(OH) 2
Strength Weak Acid/Base does not ionize completely few ions produced weak electrolyte - + HF CH 3 COOH H 3 PO 4 H 2 CO 3 HCN NH 3
Determining Types of Reactions
Neutralization Chemical reaction between an acid and a base. Products are a salt (ionic compound) and water. ACID + BASE SALT + WATER HCl + NaOH NaCl + H 2 O Salts can be neutral, acidic, or basic. Neutralization does not mean pH = 7.
Single Replacement A + BC B + AC Whether one metal will replace another metal from a compound is determined by the reactivities of the two metals. To help us determine this, an activity series of metals arranges metals in order of decreasing reactivity. A reactive metal will replace any metal listed below it in the activity series.
Precipitation Reactions Double replacement reaction where a precipitate is formed due to the insolubility of the compound that is formed. Refer to the solubility rules.
Oxidation numbers The apparent charge assigned to an atom of an element – Metal: positive charge – Nonmetal: negative charge Key points to remember: – The sum of the oxidation numbers of the elements in any compound is 0. – The sum of the oxidation numbers of the elements in any ion (polyatomic) is equal to the charge on the ion.
Reduction-oxidation reactions (redox) Any chemical reaction in which changes in oxidation numbers occur Has two parts: – Oxidation: one reactant is losing electrons or increases in oxidation number The reactant losing electrons or increasing in oxidation number is known as the reducing agent – Reduction: other reactant is gaining electrons or decreases in oxidation number The reactant gaining electrons or decreasing in oxidation number is known as the oxidizing agent
Using oxidation numbers If there are changes in atomic oxidation numbers in the reaction, meaning loss and gain of electrons, then the reaction IS redox. If there are no changes in atomic oxidation numbers then the reaction IS NOT redox.