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General properties

General properties. ACIDS Taste sour Turn litmus React with active metals – Fe, Zn React with bases. BASES Taste bitter Turn litmus Feel soapy or slippery (react with fats to make soap) React with acids. blue to red. red to blue.

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General properties

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  1. General properties ACIDS • Taste sour • Turn litmus • React with active metals – Fe, Zn • React with bases BASES • Taste bitter • Turn litmus • Feel soapy or slippery (react with fats to make soap) • React with acids blue to red red to blue

  2. There are a number of definitions for acid and bases, depending on what is convenient to use in a particular situations Arrehenius • Acids – produce H+ • Bases - produce OH- • Acids – donate H+ • Bases – accept H+ • Acids – accept e- pair • Bases – donate e- pair only in water Bronsted-Lowry any solvent Lewis used in organic chemistry, wider range of substances

  3. Examples Arrhenius HCl NaOH Bronsted-Lowry HCl HCN NH3 :NH3 Lewis BF3 Neutralization In general: Acid + Base  Salt + Water All neutralization reactions are double displacement reactions. HCl + NaOH NaCl + HOH HCl + Mg(OH)2 H2SO4 + NaHCO3

  4. The Bronsted-Lowry Concept HCl + NH3 → NH4+ + Cl- Acid base conj. acid conj. base Conjugate pairs HClCl- Acis and conj. base CH3COOHCH3COO- Acis and conjugated base HNO3NO3- Acis and conjugated base NH4+NH3 Base and conj. acid How does a conjugate pair differ? H+transfer

  5. Let’s examine the behavior of an acid, HA, in aqueous solution. HA What happens to the HA molecules in solution?

  6. 100% dissociation of HA HA H+ Strong Acid A- Would the solution be conductive?

  7. Partial dissociation of HA HA H+ Weak Acid A- Would the solution be conductive?

  8. HA  H+ + A- HA H+ Weak Acid A- At any time, only a fraction of the molecules are dissociated.

  9. Strong and Weak Acids/Bases Strong acids/bases – 100% dissociation into ions HClNaOH HNO3KOH H2SO4 Weak acids/bases – partial dissociation, both ions and molecules are present CH3COOHNH3

  10. - H+ + H+ Amphoteric substances: substances that react with acids as a base and with bases as acids Acting like a base Acting like an acid HCO3- H2CO3 CO3-2 accepts H+ donates H+

  11. - H+ + H+ Show how water can be amphoteric. H2O H3O+ OH-

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