This document discusses three types of chemical reactions that occur in water: precipitation reactions, acid-base reactions, and oxidation-reduction reactions. Precipitation reactions involve the formation of an insoluble ionic compound from ions in solution. Acid-base reactions involve acids donating protons and bases accepting protons to form water. Oxidation-reduction reactions involve the exchange of electrons between reactants, with one species being reduced and the other being oxidized.

1. Chemical Reaction
Occurring in Water

2. Aqueous Solution
• The word aqueousmeans
pertaining to, related to, similar
to, or dissolved in water.
• Asolution in which the solvent is
water.

3. • Aqueous solutions that conduct electric
current efficiently contain strong
electrolytes, while ones that conduct
poorly are considered to have weak
electrolytes. Those strong electrolytes
are substances that are completely
ionized in water, whereas the weak
electrolytes exhibit only a small degree of
ionization in water.

4. Three important types of
reactions in water:

5. Precipitation Reactions
• In a precipitation reaction, an
anion and a cation contact each
other and an insoluble ionic
compound precipitates out of
solution.

6. Example:
• When aqueous solutions of silver
nitrate, AgNO3, and salt, NaCl, are
mixed, the Ag+ and Cl- combine to
yield a white precipitate of silver
chloride, AgCl:
Ag+(aq) + Cl-(aq) → AgCl(s)

7. Acid-Base Reactions
• Is a chemical reaction that
occurs between an acid and
a base

8. Example:
• When hydrochloric acid, HCl, and sodium
hydroxide, NaOH, are mixed, the H+
reacts with the OH- to form water:
H+(aq) + OH-(aq) → H2O
HCl acts as an acid by donating H+ ions or
protons and NaOH acts as a base,
furnishing OH- ions.

9. Oxidation-Reduction Reactions
– In an oxidation-reduction or redox reaction, there
is an exchange of electrons between two
reactants. The species that loses electrons is said
to be oxidized. The species that gains electrons is
said to be reduced. An example of a redox
reaction occurs between hydrochloric acid and
zinc metal, where the Zn atoms lose electrons and
are oxidized to form Zn2+ ions:
• Zn(s) → Zn2+(aq) + 2e-

10. – The H+ ions of the HCl gain electrons and
are reduced to H atoms, which combine to
form H2 molecules:
2H+(aq) + 2e- → H2(g)
– The overall equation for the reaction
becomes:
Zn(s) + 2H+(aq) → Zn2+(aq) + H2(g)