Unformatted text preview: d b ase salt w ate r Salts are ionic substances wit h the cation donated fro m the base and the anion donated from the acid. In the laboratory, neutralization reactions are observed by an increase in temperature (exothermic react ion). 3. Unstable product: Some chemical reactions produce gas because one of the products formed in the reaction is unstable. Two such products are listed below: Carbonic acid Sulfurous acid H2CO3 (aq) ® CO2 (g) + H2O (l) H2SO3 (aq) ® SO2 (g) + H2O (l) When eit her of these products appears in a chemical react ion, they should be replaced wit h their deco mposit ion products. 2 HCl (aq) + Na2CO3 (aq) ® 2 NaCl (aq) + H2CO3 (aq) (unstable) 2 HCl (aq) + Na2CO3 (aq) ® 2 NaCl (aq) + CO2 (g) + H2O (l) 7 Chemistry 51 Chapter 6 DOUBLE REPLACEMENT REACTIONS Examples: Complete and balance each neutralizat ion reaction below: 1. HNO3 (aq) + Ba(OH)2 (aq) ® 2. H2SO4 (aq) + NaOH (aq) ® 3. HC2H3O2 (aq) + KOH (aq) → Complete and balance the unstable product reaction shown below: 4. HNO3 (aq) + K2SO3 (aq) ® 8 Chemistry 51 Chapter 6 OXIDATIONREDUCTION REACTIONS
· React ions known as oxidation and reduction (redox) have many important applicat ions in our everyday lives. Rusting of a nail or the reaction within your car batteries are two examples of redox reactions.
· In an oxidat ionreduction react ion, electrons are transferred fro m one substance to another. If one substance loses electrons, another substance must gain electrons. · Oxidation is defined as loss of electrons, and reduction is defined as gain of electrons. One way to remember these definit io ns is to use the following mnemo nic: OIL RIG Oxidat ion Is Loss of electrons Reduction Is Gain of electrons · Combinat ion, decomposit ion, single replacement and co mbust ion reactions are all examples of redox reactions. 9 Chemistry 51 Chapter 6 OXIDATIONREDUCTION REACTIONS
· In general, atoms of metals lose electrons to form cations, and are therefore oxidized, while atoms of nonmetals gain electrons to form anio ns, and are therefore reduced.
· For example, in the formation o f calcium sulfide from calcium and sulfur Ca + S → CaS 2
Ca → Ca + + 2 e oxidized (loses electrons) –
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