Chemical Chemical ReactionsReactions

Types of Chemical Types of Chemical ReactionsReactionsAcid-Base Reactions

• Neutralization ReactionsNeutralization ReactionsIn a reaction involving HCN(aq), a weak acid, and KOH(aq), a strong base, the product is KCN, a strong electrolyte

Acid + Base yields water + salt

HA + BOH yields H2O + BA

HCN(aq) + KOH(aq) H2O(l) + KCN(aq)

Types of Chemical Types of Chemical ReactionsReactionsAcid-Base Reactions

• Acid-Carbonate ReactionsAcid-Carbonate ReactionsCarbonates react with acids to form CO2, carbon dioxide gas.

BCO3 + HA yields BA + H2O + CO2

2232 COOHNaCl2HCl2CONa

Acid/Base IndicatorsAcid/Base Indicators

• Most acids and bases as well as the Most acids and bases as well as the resulting salt solution are colorless.resulting salt solution are colorless.– In order to determine when the reaction is In order to determine when the reaction is

complete, we must use chemical complete, we must use chemical indicators.indicators.•Chemical IndicatorsChemical Indicators in the case of acid/base in the case of acid/base

reactions are weak acids that have the reactions are weak acids that have the property of changing colors when going from property of changing colors when going from basic to acidic solutions or vice-versa.basic to acidic solutions or vice-versa.

•The most used acid/base indicator is The most used acid/base indicator is phenolphthalein. phenolphthalein.

Types of Chemical Types of Chemical ReactionsReactions• Combination ReactionsCombination Reactions

Synthesis Reactions (combination)

A combination reaction is a reaction in which two substances, usually two elements, combine to form a third substance..

A + A + B B yields Ayields ABB

)(2)()(2 2 sNaClgClsNa

Types of Chemical Types of Chemical ReactionsReactions• Combination ReactionsCombination Reactions

Oxidation-Reduction Reactions

Other combination reactions involve compounds as reactants.

)s(CaSO)g(SO)s(CaO 32

CrystallizationCrystallization

• Ions combine to form an ionic Ions combine to form an ionic compoundcompound

• AA++(aq)(aq)

+ B+ B--(aq) (aq) AB AB(s)(s)

• MgMg2+2+(aq)(aq) + O + O2-2-

(aq)(aq) MgO MgO(s)(s)

• 2 NH2 NH44++

(aq)(aq) + S + S2-2- (NH (NH44))22SS(s)(s)

DissociationDissociation

• An ionic compound is placed in water An ionic compound is placed in water and dissociates into its ionsand dissociates into its ions

• MgFMgF2(s)2(s) Mg Mg2+2+(aq)(aq) + 2 F + 2 F--

(aq)(aq)

• NaNa22COCO3(s)3(s) 2 Na 2 Na++(aq)(aq) + CO + CO33

2-2-(aq)(aq)

DissociationDissociation

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Water Solvation of IonsWater Solvation of Ions

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Neutralization ReactionNeutralization Reaction

Neutralization reaction between Acetic Acid (Vinegar) and Baking Soda (Sodium

Bicarbonate).