1 / 14

UNIT 5

UNIT 5. Aqueous Reactions and Solution Stoichiometry Acid-Base Neutralization. Writing Equations for Reactions Involving Ions. There are three ways to write equations for reactions involving ions. Molecular equation: HCl (aq) + AgNO 3 (aq)  AgCl (s) + HNO 3 (aq)

sumana
Download Presentation

UNIT 5

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. UNIT 5 Aqueous Reactions and Solution Stoichiometry Acid-Base Neutralization

  2. Writing Equations for Reactions Involving Ions • There are three ways to write equations for reactions involving ions. • Molecular equation: • HCl (aq) + AgNO3 (aq)  AgCl (s) + HNO3 (aq) • Here no ions are shown but all reactants and products are identified and their physical states given. • Complete or Total Ionic Equation: • H+ (aq) + Cl- (aq) + Ag+ (aq) + NO3- (aq)  AgCl (s) + H+ (aq) + NO3- (aq) • Here ALL ions are shown as they exist in solution. Spectator ions do not participate in the reaction but are shown. • Net ionic equation: • Cl- (aq) + Ag+ (aq)  AgCl (s) • Here only ions which participate in the reaction are shown. Spectator ions are NOT shown.

  3. Writing Equations for Reactions Involving Ions • Write the three equations for the reaction between solutions of barium nitrate and sodium phosphate. • Molecular equation: • 2Na3PO4 (aq) + 3Ba(NO3)2 (aq)  Ba3(PO4)2 (s) + 6NaNO3 (aq) • Complete or Total Ionic Equation: • 6Na+ (aq) + 2PO43- (aq) + 3Ba2+ (aq) + 6NO3- (aq)  Ba3(PO4)2 (s) + 6Na+ (aq) + 6NO3- (aq) • Net ionic equation: • 2PO43- (aq) + 3Ba2+ (aq)  Ba3(PO4)2 (s) • The net ionic equation says that ANY soluble compound with phosphate and ANY soluble compound with barium ion will react to form the barium phosphate precipitate.

  4. Acid-Base Neutralization • Metathesis reactions are reactions of the form: AX + BY  AY + BX • If either of the POSSIBLE new compounds AY or BX is: • insoluble in water (a precipitate) • a weak electrolyte • a gas • then the metathesis reaction will occur. • Acid-base neutralization is a metathesis reaction. The product of the neutralization is either a weak electrolyte (usually water) or a gas.

  5. Acid-Base Neutralization • Acid-base neutralization is a metathesis reaction between an acid and a base. • HX + BOH BX + HOH ( = H2O ) • Definitions of acids and bases • Acids • produce H+ in water (Arrhenius) • are proton donors (proton = H+) (Brønsted-Lowry) • Bases • produce OH- in water (Arrhenius) • are proton acceptors (Brønsted-Lowry)

  6. Acid-Base Neutralization • Acid-base neutralization is a metathesis reaction between an acid and a base. • HX + BOH  BX + H2O • acid + base  water • (a weak electrolyte) • Acids are proton donors (proton = H+). • Bases are proton acceptors and are metal hydroxides, ammonia, the amines and alcohols: • HCl+ NH3 NH4+ + Cl-  NH4Cl(s) • acid + ammonia  salt

  7. Acid-Base Neutralization • In a neutralization, the acid and the base are reactants. Identify the acid and the base in the following reactions (hint: look for the H+): • CH3OH + HBr CH3OH2+ + Br - • CH3NH2 + H2O  CH3NH3+ + OH- • Here, the acids had the H at the left of the formula (HBr, HOH). • (It is helpful to know the Lewis structures of ammonia and of water.)

  8. Acid-Base Neutralization • Identify the acid and the base in the following reactions: • CH3CO2H + KOH  CH3CO2- K++ H2O • CH3COOH+ CH3Li  CH3CO2-Li++ CH4 • Organic acids (CO2H or COOH) have the acid H at the right of the formula. • Here are two more: • CH3OH+ NaH CH3O- Na++ H2 • C4H9Li + H2O  C4H10 + LiOH (Li+ and OH-)

  9. Acid-Base Neutralization • KNOW THE STRONG ACIDS: HCl, HBr, HI, HClO3, HClO4, HNO3, H2SO4 by name AND formula. • These ionize completely in water. HCl(aq)  H+(aq) + Cl-(aq) • KNOW THE STRONG BASES: LiOH, NaOH, KOH, RbOH, CsOH (these are Group 1A metal hydroxides), Ca(OH)2, Sr(OH)2, and Ba(OH)2, by name AND formula. • These ionize completely in water. Ba(OH)2(aq)  Ba2+(aq) + 2OH-(aq) • 2HCl(aq) + Ba(OH)2(aq)  2H2O(l) + BaCl2(aq) • NET IONIC REACTION BETWEEN A STRONG ACID AND A STRONG BASE: H+(aq) + OH-(aq)  H2O(l)

  10. Acid-Base Neutralization - Examples Acetic acid is neutralized by a solution of potassium hydroxide: M.E.: HC2H3O2 (aq) + KOH (aq) KC2H3O2 (aq) + H2O (l) Complete ionic equation: HC2H3O2(aq) + K+(aq) + OH-(aq) K+ (aq) + C2H3O2- (aq) + H2O (l) Net ionic equation: HC2H3O2(aq) + OH-(aq) C2H3O2-(aq) + H2O(l)

  11. Acid-Base Neutralization - Examples Solid magnesium hydroxideis neutralized by hydroiodic acid: M.E.: Mg(OH)2 (s) + 2HI (aq) MgI2 (aq) + 2H2O (l) Complete ionic equation: Mg(OH)2 (s) + 2H+ (aq) + 2I- (aq) Mg2+ (aq) + 2I- (aq) + 2H2O (l) Net ionic equation: Mg(OH)2 (s) + 2H+ (aq)  Mg2+ (aq) + 2H2O (l)

  12. Acid-Base Neutralization with Gas Formation Hydrochloric acidreacts with a solution of sodium sulfide. One of the products is a gas. Molecular Equation: 2HCl (aq) + Na2S (aq) 2NaCl (aq) + H2S (g) acid base salt gas The sulfide ion acts as a proton acceptor and is therefore the base. Complete ionic equation: 2H+(aq) + 2Cl-(aq) + 2Na+(aq) + S2-(aq) 2Cl-(aq) + 2Na+(aq) + H2S (g) Net ionic equation: 2H+(aq) + S2-(aq) H2S (g)

  13. Acid-Base Neutralization Recognize the “gases in disguise:” H2SO3, H2CO3 and NH4OH. These compounds are unstable in water and decompose to form a gas and water. H2SO3 (aq) H2O (l) + SO2 (g) H2CO3 (aq) H2O (l) + CO2 (g) NH4OH (aq) H2O (l) + NH3 (g)

  14. Acid-Base Neutralization Hydrochloric acidis neutralized by a solution of sodium sulfite. 2HCl (aq) + Na2SO3 (aq) 2NaCl (aq) + H2SO3 (aq) Molecular equation: 2HCl (aq) + Na2SO3 (aq) 2NaCl (aq) + H2O (l) + SO2 (g) The sulfite ion acts as a proton acceptor and is therefore the base. Complete ionic equation: 2H+(aq) + 2Cl-(aq) + 2Na+(aq) + SO32-(aq) 2Cl-(aq) + 2Na+(aq) + H2O(l) + SO2 (g) Net ionic equation: 2H+(aq) + SO32-(aq) H2O (l) + SO2 (g)

More Related