Presentation on theme: "Acids Taste sour Reach with certain metals (Zn, Fe, etc.) to produce hydrogen gas cause certain organic dyes to change color react with limestone."— Presentation transcript:
Acids Taste sour Reach with certain metals (Zn, Fe, etc.) to produce hydrogen gas cause certain organic dyes to change color react with limestone (CaCO3) to produce carbon dioxide React with bases to form salts and water
Bases Taste bitter feel slippery or soapy react with oils and grease cause certain organic dyes to change color react with acids to form salts and water
Similarities Taste sour Reacts with each other to form salts and waters Causes certain organic dyes to change colors
Definitions of acids A substance that produces Protons, H+
Definitions of bases A substance that produces Hydroxide ions, OH-
Reactions of acids and bases with water Acids and bases form ions in solution: HCl(aq) ® H + (aq) + Cl - (aq) H 3 O + - hydronium ion H + and H 3 O + are equivalent in aq. solution When we look at the reactions of acids - can be generalized using hydrogen ion Reaction with zinc yields hydrogen gas Reaction with limestone - produce CO2(g) Acids react with bases to produce a salt Similarly for bases, produce hydroxide ions
Neutralization and salts Neutralization - one type of double replacement reaction Acid + Base ® Salt + water Net ionic equation shows what drives the neutralization reaction example: Molecular: HCl(aq) + NaOH(aq) ® NaCl(aq) + H2O(l) Total Ionic: H+(aq) + Cl-(aq) + Na+(aq) + OH-(aq) ® Na+(aq) + Cl-(aq) + H2O(l) Net Ionic: H+(aq) + OH-(aq) ® H2O(l) SALT - a salt is formed from the anion of the acid and the cation of the base - usually present as spectator ions. - not always NaCl
Types of acids Monoprotic - a solution that produces one mole of H+ ions per mole of acid HCl, HNO3 Diprotic - a solution that produces two moles of H+ ions per mole of acid H2SO4 Triprotic - a solution that produces three moles of H+ ions per mole of acid H3PO4 Polyprotic - two ore more H+ per mole of acid V. Polyprotic acids: can be Partially neutralized acid salt - an ionic compound containing the anion with one or more hydrogens that can be neutralized with a base
Strengths of Acids and Bases STRONG ACIDS Acids that are essentially 100% ionized in aqueous solutions ex: HCl, HNO3, HClO4 produce the maximum concentration of H+ [acid] = [H+] WEAK ACIDS Acids that are partially ionized ( usually less than 5%) in equilibrium. HF + H2O(l) H3O+(aq) + F-(aq) The forward and the reverse reaction are occurring simultaneously most found as HF. STRONG BASES those compounds that completely ionize in water to produce OH- ions NaOH(s) ® Na+(aq) + OH-(aq) Concentration of base = concentration of hydroxide ions WEAK BASES NH3(aq) + H2O(l) NH4+(aq) + OH-(aq) equilibrium lies far to the left (mostly reactants present)
Equilibrium of Water H2O(l) + H2O(l) H3O+(aq) + OH-(aq) Autoionization - produces positive and negative ions from the dissociation of the molecules of a liquid. Experimentally, found concentration of ions = 1.0 x 10-7 M at 25 C [H3O+][OH-] = Kw At 25 C (1.0 x 10-7)(1.0 x 10-7) = 1.0 x 10-14 Kw = ION PRODUCT - gives us the concentrations of hydronium and hydroxide ions in pure water and acidic and basic solutions Neutral[H3O+] = [OH-] = 1.0 x 10-7 M Acidic[H3O+] > 1.0 x 10-7, [OH-] <1.0 x 10-7 Basic[H3O+] 1.0 x 10-7
Brønsted-Lowry Acids and Bases acid - a proton (H+) donor base - a proton (H+) acceptor NH3(aq) + H2O(aq) NH4+(aq) + OH- (aq) NH3 and NH4+ are conjugate acid-base pairs H2O and OH- are conjugate acid-base pairs Amphiprotic - a compound or ion that can either donate or accept H+ ions. H2O, HSO4-, HPO42-, HSO3- etc.
Acidic and Basic Salt solutions Hydrolysis - the reaction of an anion with water to produce OH- or the reaction of a cation to produce H3O+ Neutral solutions of salts: Cation does not undergo hydrolysis Anion does not undergo hydrolysis Basic solutions of salts: Cation same as above Anion undergoes some hydrolysis Acidic solutions of salts: Cation undergoes some hydrolysis Anion does not Complex solutions: Cation and anion undergoes hydrolysis Then you need to know the relative strength of each.
. Predicating acid base reactions in water Acid-Base reactions always yield conj. acid-base Strong Acid : weak conj. base Strong Base : weak conj. acid Weak Acid : strong conj. base Weak Base : strong conj. acid The strength of the reactant compared to the strength in the product determines which direction the equilibrium lies. Three predictions can be made: The reactant may Not react at all, leaving essentially all reactants (negligible) The reactants may Slightly react, leaving mostly reactants (limited) The reactants may react (essentially) completely, leaving little or no reactants (favorable)
Buffer solutions Buffer solution - resists changes in pH caused by the addition of limited amounts of a strong acid or a strong base. A buffer solution must contain: A weak acid + its conjugate base or A weak base + its conjugate acid
Citation PAge "Chapter 12 - Acids and Bases." Modesto Junior College. N.p.. Web. 16 Nov 2012..
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