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Chapter 10 Chemical Reactivity. Four Common Reaction Types : 1) Combination 2) Decomposition 3) Single-replacement 4) Double-replacement But first! Let’s look at polyatomic ions. Compounds Containing Polyatomic Ions.
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Four Common Reaction Types: 1) Combination 2) Decomposition 3) Single-replacement 4) Double-replacement But first! Let’s look at polyatomic ions
Compounds Containing Polyatomic Ions • Polyatomic ions: single ions containing > one atom covalently bonded • Often look for parentheses Ca(OH)2 • Name & charge of polyatomic ion does notD • Note: no ( ) for single polyatomic group
Patterns for Polyatomic Ions • Elements in same column form similar • polyatomic ions - same # O’s &same charge:
Patterns for Polyatomic Ions • If polyatomic ion starts with an H • add “hydrogen” prefix before name • and add +1 to charge CO32−= carbonate HCO3− = hydrogen carbonate
Patterns for Polyatomic Oxyanions • -ate ion e.g. Chlor______= ClO3− • -ate ion +1 ex O same charge, _____prefix • e.g. ______________= ClO4− • -ate ion –1 O same charge, _____suffix • e.g. Chlor______= ClO2− • -ate ion –2 O same charge, • e.g. _______________= ClO− • ______prefix, • ______ suffix
Naming ionic compounds containing a polyatomic ion e.g. Na2SO4 • 1. Identify the ions Na = Na+ because in Group 1A SO4 = SO42− a polyatomic ion • 2. Name the cation Na+ = sodium, metal with invariant charge • Name the anion SO42− = • 4. Write cation name followed by name of anion
Fe(NO3)3 • Identify ions • NO3= NO3− a polyatomic ion Fe = Fe3+ to balance charge of 3 NO3− ions • 2. Name cation Fe3+ = iron(III), metal with variable charge • Name anion NO3− = • 4. Write cation name followed by anion name
Practice — What are the formulas for compounds made from the following ions? aluminum ion with a sulfate ion chromium(II) with hydrogen carbonate
Four Common Reaction Types: 1) Combination Elem + elem one prod Elem + Cmpnd one prod Cmpnd + Cmpnd one prod
Four Common Reaction Types: 1) Combination Elem + elem one prod metalelement + elementalO2 ionic metal oxide e.g. 4Al(s) + 3O2(g) 2Al2O3(s) lattice E (solid)
Four Common Reaction Types: 1) Combination Elem + elem one prod Non-metalelement+ elem.O2 covalent oxide e.g. Combustion rxtn: S(s) + O2(g) SO2(g) volatile product gas
Four Common Reaction Types: 1) Combination Compound + Compound one product e.g. metal oxide + CO2 or SO3 What practical environmental applications for these 2 rxtns can you think of?
Hydrates • ionic compounds containing a specific # of waters surrounding each formula unit • Water of hydration “driven off” by heating Cobalt (II) chloride _______________ CoCl2 Cobalt (II) chloride _______________ CoCl2. 6H2O
Hydrates • In formula, attached H2O’s follow a ∙ • CoCl2∙6H2O
Hydrates • attached waters indicated by prefix+hydrate after name of ionic compound • CoCl2∙6H2O = • CaSO4∙½H2O =
Anhydrous salts are ____________________ = absorb ________even from atmosphere Used as __________________
Practice What is the formula of magnesium sulfate heptahydrate? What is the name of NiCl2•6H2O?
Solutions • Homogeneous mixtures = solutions • Part of solution that D’s state = the solute • Part that keeps its state = the solvent • if both parts in same state, major part is the solvent 22
What Happens When a Solute Dissolves? When solute & solvent mix, there are attractive forces btwnsolute & solvent molecules If attractions btwnsolute and solvent are strong enough, the solute will dissolve 23
Table Salt Dissolving in Water Each ion is attracted to surrounding water molecules & pulled off & away from crystal. ion is surrounded by water molecules, = ________________ Solvated ion lower in E than ions in crystal lattice
Table Salt Dissolving in Water Result: soltn with free moving charged particles - can conduct electricity 25
Dissociation and Ionization • Dissociation: ionic compounds dissolve in water, anions & cations are separated: Na2S(s) 2 Na+(aq) + S2-(aq) H2O(l) • Compounds w/ polyatomic iondissociating, polyatomic group stays together as one ion: Na2SO4(s) H2O(l) 26
Non-electrolyte solutions: whole molecules dissolved in water Generally, molecular compounds do _____________when they dissolve • exception is 27
Salt vs. Sugar Dissolved in Water ionic compounds dissociate into ions when they dissolve molecular compounds do not dissociate when they dissolve
Acids and Bases • Acids: molecular compounds that ionize when dissolved in water • molecules ripped apart when attracted by water • acids ionize 29
Acids and Bases in Solution • Acids ionize in water H+ ions H from acid molecule _____________ion, (we use H+& H3O+interchangeably) 30
Dissociation and Ionization • When strong acids dissolve in water, the molecule ionizes into H+ (actually H3O+) & anions H2SO4(aq) 31
Acids and Bases • Bases: ionic compounds that dissociate when dissolved in water OH-anion +a metal cation KOH(s) + H2O (l) 32
Common Reaction Types: 1) Combination Group I & II Metal oxides + H2O a base(aq) Na2O(s) + H2O(l) Na+(aq) + OH-(aq) water is both a reactant and solvent Other metal oxides are more inert
Common Reaction Types: 1) Combination H with non-metal + H2O an acid (aq) Water pops H+ off & leaves a solvated anion
Only name as an acid • if molecule is dissolved in water -(aq) subscript • hydrochloric acid vs. hydrogen chloride gas
Common Reaction Types: Note: not every compound with H atoms will donate them as an acid.
Acids • Sour taste • Dissolve many metals • - e.g. Zn, Fe, Mg; • - but not Au, Ag, Pt • Formula generally starts with H • e.g. 37
Reaction of Acids with Metals H2 gas 38
Acids • Organic (carboxylic) acids: • -COOH functional group Organic? That’s totally “cooh” with me! 39
Acids • Binary acids H+cationand non-metal anion • Oxyacids have H+cation & ________________ 40
Naming Binary Acids Write a hydro prefix Follow with non-metal name Changeending on non-metal name to –ic Write acid at end of name 41
Example: HCl(aq) • Identify non-metal anion Cl = Cl−, chloride because Group 7A • 2. anion D to –icsuffix • Cl− = chloride • 3. Add hydro- prefix to anion • 4. Add word acid to end: 43
Naming Oxyacids • If polyatomic ion name ends in –ate, then change ending to ____suffix • If polyatomic ion name ends in –ite, then change ending to ______suffix • Write word acid at end of all names 44
Example: Naming oxyacids HNO3(aq) • 1. ID anion NO3= NO3−= nitrate • –ate suffix, D to –ic. • –ite suffix, D to -ous • NO3−= nitrate • Write anion name followed by “acid” 46
Example: Naming oxyacids HNO2(aq) • 1. ID anion NO3= NO3−= nitrite • –ate suffix, D to –ic. • –ite suffix, D to -ous • NO3−= nitrite • Write anion name followed by “acid” 47
Example: Naming oxyacids H2SO4(aq) • 1. ID anion SO4 = SO42− = sulfate • –ate suffix, D to –ic. • –ite suffix, D to -ous • SO42− = sulfate • Write anion name followed by “acid” 48
Example: Naming oxyacids H2SO3(aq) • ID the anion SO3 = SO32− = sulfite • –ate suffix, D to –ic. • –ite suffix, D to -ous • SO32− = sulfite • Write anion name followed by “acid” 49
Name the Following H2S HClO3 H3PO3 50