View
240
Download
0
Tags:
Embed Size (px)
Citation preview
Chemical Reactions
Chapter 13
Acids
• Have a sour taste. Vinegar owes its taste to acetic acid.Have a sour taste. Vinegar owes its taste to acetic acid.Citrus fruits contain citric acid.Citrus fruits contain citric acid.
• React with certain metals to produce hydrogen gas.React with certain metals to produce hydrogen gas.
• React with carbonates and bicarbonates to produce carbon React with carbonates and bicarbonates to produce carbon dioxide gas.dioxide gas.
• Cause color changes in plant dyes.Cause color changes in plant dyes.
2HCl (2HCl (aqaq) + Mg () + Mg (ss) MgCl) MgCl22 ( (aqaq) + H) + H22 ( (gg))
2HCl (2HCl (aqaq) + CaCO) + CaCO33 ( (ss) CaCl) CaCl22 ( (aqaq) + CO) + CO22 ( (gg) + H) + H22O (O (ll))
• Aqueous acid solutions Aqueous acid solutions (aq)(aq) conduct electricity. conduct electricity.
• Have a bitter taste.Have a bitter taste.
• Feel slippery. Many soaps contain bases.Feel slippery. Many soaps contain bases.
BasesBases
• Cause color changes in plant dyes.Cause color changes in plant dyes.
• Aqueous base solutions Aqueous base solutions (aq)(aq) conduct electricity. conduct electricity.
ammoniaammoniahydroxide ionhydroxide ion
(“milk of magnesia”)
acid - a hydrogen ion donorbase - a hydrogen ion acceptor
acid base
A hydrogen ion, H+, is the same as a proton!
Hydronium ion, hydrated proton, H3O+
Electron-rich region
Electron-poor region
Figure 13.3
HH
HHHH
OO
acidbase
acid - a hydrogen ion donorbase - a hydrogen ion acceptor
acid base
Neutralization Reaction
acid + base salt + water
HCl (aq) + NaOH (aq) NaCl (aq) + H2O
SaltsSalts
HCl (aq) + KOH (aq) KCl (aq) + H2O
Solutions: Acidic, Basic or NeutralNeutral
HCl (aq) + H2O (l) → Clˉ (aq) + H3O+ (aq)
acid base
acidbase
NH3 (aq) + H2O (l) ⇌ NH4+ (aq) + OHˉ (aq)
Water is amphoteric – can behave as an acid or base
How do we express the concentration
of an acid or a base?
pH scale – based on concentration of the
hydronium ion (H3O+)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
acidic basicneutral
Based on powers of 10:
e.g., a soln with pH = 3 is 10 times moreacidic than a solution with pH = 4
Common substances that are acidic
pH Values of Some Common Solutions
Red Cabbage Juice Used to Determine pH
Oxidation-Reduction (Redox) Reactions(electron transfer reactions)
2Na (s) + Cl2 (g) 2NaCl (s)
2Na 2Na+ + 2e-
Cl2 + 2e- 2Clˉ
Oxidation half-reaction (lose e-)
Reduction half-reaction (gain e-)
2Na + Cl2 + 2e- 2Na+ + 2Cl- + 2e-
2Na + Cl2 2NaCl
2Na (s) + Cl2 (g) 2NaCl (s)
Na is the reducing agent
Cl2 is the oxidizing agent
Reducing agentsReducing agents(be oxidized)(be oxidized)
Oxidizing agentsOxidizing agents(be reduced)(be reduced)