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Acids and Bases

Acids and Bases. Acids. from the Latin word acere  “ sharp ” or “ sour ” taste sour (but you wouldn ’ t taste an acid to see) change litmus paper red corrosive to some metals (reacts to create hydrogen gas – H 2 ) a substance that can donate a hydrogen ion (H + ) to another substance

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Acids and Bases

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  1. Acids and Bases

  2. Acids • from the Latin word acere “sharp” or “sour” • taste sour (but you wouldn’t taste an acid to see) • change litmus paper red • corrosive to some metals (reacts to create hydrogen gas – H2) • a substance that can donate a hydrogen ion (H+) to another substance • create a hydrogen ion (H+) or hydronium ion (H3O+) when dissolved in water H2O Notice how the hydrogen ion is released when the acid is in water HCl  H+ + Cl- Hydrogen ion Chloride ion Hydrochloric Acid Examples: hydrochloric acid, vinegar, lemon juice, rainwater

  3. Bases • taste bitter (but you wouldn’t taste a base to see) • feel slippery or soapy • change litmus paper blue • react with oils and grease • a substance that can accept a hydrogen ion (H+) from another substance • create a hydroxide ion (OH-) when dissolved in water Notice how the hydroxide ion is released when the base is in water; this ion can accept a hydrogen ion (H+) H2O NaOH  Na+ + OH- Sodium Hydroxide Sodium ion Hydroxide ion Examples: sodium hydroxide, Drano, Tums, baking soda

  4. Acid/Base definitions Definition 1: Arrhenius Arrhenius acid is a substance that produces H+ (H3O+) in water Arrhenius base is a substance that produces OH- in water 4.3

  5. Acid/Base Definitions Definition #2: Brønsted– Lowry Acids – proton donor Bases – proton acceptor A “proton” is really just a hydrogen atom that has lost it’s electron.

  6. A Brønsted-Lowry acid is a proton donor. A Brønsted-Lowry base is a proton acceptor. conjugatebase conjugateacid base acid

  7. ACID-BASE THEORIES The Brønsted definition means NH3 is aBASE in water — and water is itself anACID

  8. Conjugate Pairs

  9. Learning Check! Label the acid, base, conjugate acid, and conjugate base in each reaction: HCl + OH-   Cl- + H2O Acid Base Conj.Base Conj.Acid H2O + H2SO4   HSO4- + H3O+ Conj.Base Conj.Acid Base Acid

  10. The pH scale is a way of expressing the strength of acids and bases. Instead of using very small numbers, we just use the NEGATIVE power of 10 on the Molarity of the H+ (or OH-) ion.Under 7 = acid 7 = neutral Over 7 = base

  11. Neutralization Reaction • occurs when acids and bases react with each other to produce water and salt • acids release a hydrogen ion (H+) and bases release a hydroxide ion (OH-)  water (H2O) • the negative ion from the acid joins with the positive ion of a base  salt HCl + NaOH  H2O + NaCl Hydrochloric Acid (acid) Sodium Hydroxide (base) Sodium Chloride (salt) Water Both the salt and water are neutral substances; therefore, that is why this is referred to as a neutralization reaction.

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