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Electrolytes & Nonelectrolytes

Electrolytes & Nonelectrolytes. Electrolytes. An electrolyte is a substance that becomes ions when dissolved in water. (Conducts electricity) A nonelectrolyte may dissolve in water, but it does not dissociate into ions when it does so. Water. Water is a good solvent for ionic compounds

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Electrolytes & Nonelectrolytes

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  1. Electrolytes & Nonelectrolytes

  2. Electrolytes • An electrolyte is a substance that becomes ions when dissolved in water. (Conducts electricity) • A nonelectrolyte may dissolve in water, but it does not dissociate into ions when it does so.

  3. Water Water is a good solvent for ionic compounds because it’s polar. O – H І H - + + Negative ions are attracted to the positive hydrogen Positive ions are attracted to the negative oxygen

  4. Electrolytes Soluble ionic compounds tend to be electrolytes. NaCl(s)  Na+ (aq) + Cl- (aq)

  5. Nonelectrolytes Molecular compounds tend to be nonelectrolytes, except for acids and bases.

  6. Acids • An acid is usually a compound of hydrogen attached to something that looks like an anion • Substances that increase the concentration of H+ when dissolved in water (Arrhenius). • Proton donors (Brønsted–Lowry).

  7. Acids Acids are molecular, therefore they do not dissociate into ions However, there is a reaction that occurs between an acid and water HCl + H2O  H3O+ + Cl- H3O+ is a water molecule with an extra proton (H+) OR HCl  H+ + Cl- The acid is said to be ionized (not dissociated) Acids are considered electrolytes

  8. Sulfuric Acid Many acids are monoprotic (they have 1 hydrogen), but some have more than one. Sulfuric acid is diprotic and it ionizes in two steps. H2SO4 +H2O  H3O+ + HSO4- HSO4- + H2O ⇋ H3O+ + SO4-2

  9. Bases: • Usually a compound with a metal attached to the hydroxide ion. • Substances that increase the concentration of OH− when dissolved in water (Arrhenius). • Proton acceptors (Brønsted–Lowry). NH3 + H2O ⇋ NH4+ + OH-

  10. Summary • Soluble Ionic Compounds (Salts) dissociate into ions • NaCl (s)  Na+(aq) + Cl-(aq) • Bases made of a metal attached to the hydroxide ion dissociate into ions (unless insoluble/precipitate) • Ca(OH)2(aq)  Ca+2(aq) + 2OH-(aq) • Acids are ionized into H+ ions (H3O+) and anions • HCl (aq) + H2O(l)  H3O+(aq) + Cl-(aq) • The base ammonia (NH3) is ionized into NH4+ and OH- • NH3(aq) + H2O(l)  NH4+(aq) + OH-(aq)

  11. Strong Electrolytes • A strong electrolyte dissociates/ionizes completely when dissolved in water. HCl  H+ + Cl- The aqueous solution contains H+ and Cl- ions

  12. Strong Electrolytes Are… • Soluble Ionic compounds • Strong acids • Strong bases

  13. Acids There are only seven strong acids: • Hydrochloric (HCl) • Hydrobromic (HBr) • Hydroiodic (HI) • Nitric (HNO3) • Sulfuric (H2SO4) • Chloric (HClO3) • Perchloric (HClO4) (All other acids are weak)

  14. Bases The strong bases are the soluble salts of the hydroxide ion • Alkali metals • Calcium • Strontium • Barium NH3 is a common weak base

  15. Weak Electrolytes A weak electrolyte only ionizes/dissociates partially when dissolved in water HC2H3O2H+ + C2H3O2- The aqueous solution contains HC2H3O2, H+,andC2H3O2-

  16. Sulfuric Acid Again! Sulfuric acid is diprotic and it ionizes in two steps. H2SO4 +H2O  H3O+ + HSO4- HSO4- + H2O H3O+ + SO4-2 A solution of H2SO4 contains H3O+, HSO4-, and SO4-2

  17. Gases • Some acids are gases H2S 2HCl(aq) + Na2S(aq)  H2S(g) + 2NaCl(aq) H2CO3(aq) is very unstable and decomposes to make H2O (l) and CO2(g)

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