Reactions of Inorganic Substances

1
Reactions of Inorganic Substances

• Inorganic substances are all substances that do
  not contain a C-H bond

2
Inorganic Substances

• Most common inorganic substances are ionic solids
  at room temperature
• For reactions to occur, particles of reactants
  must be free to move and collide - solids tend
  not to react
• To give ions freedom of motion, inorganic
  substances need to be dissolved in a suitable
  solvent

3
Solubilities of Substances
"Like dissolves Like"
4
Inorganic Substances Bronsted Definitions

• Acid is a substance that produces hydrogen ions
  (H) in solution
• HCl gt H Cl-
• Base is a substance that produces hydroxide ions
  (OH-) in solution
• NaOH gt Na OH-
• Salt produces ions other than H and OH- in
  solution NaCl gt Na Cl-

5
Properties of Acids

• Acids dissolve many metals
• Acids have a sour taste
• Acids turn litmus paper red
• Acids react with bases to form water and a salt
  (called a neutralization reaction)

6
Properties of Bases

• Bases feel slippery
• Bases taste bitter
• Bases turn litmus paper blue
• Bases react with acids to form water and a salt
  (neutralization reaction)

7
Formation of Acids and Bases

• Acid anhydride - non-metal oxide that reacts with
  water to produce an acid
• Example CO2 H2O gt H2CO3
• Base anhydride - metal oxide that reacts with
  water to produce a base
• Example CaO H2O gt Ca(OH)2

8
Concentrations of Solutions

• Molarity (M) - the number of moles of the solute
  per liter of solution
• M moles of solute/liters of solution
• Find molarity of a solution containing 2 moles of
  HCl in 4 liters of solution
• M moles of solute/liters of solution
• M 2 moles/4 L 0.50 moles/L HCl

9
NH4Cl
http//www.iun.edu/cpanhd/C101webnotes/aqueoussol
ns/molarity.html
http//misterguch.brinkster.net/molaritytutorial.h
tml
10
Strengths of Acids and Bases

• Strong acid - acid which dissociates 100 into H
  and anions
• Weak acid - acid which dissociates ltlt 100
  into H and anions
• Strong base - base which dissociates 100 into
  OH- and cations
• Weak base - base which dissociates ltlt 100
  into OH- and cations

11
Buell/Girard, "Chemistry",Prentice Hall, NJ,
1994, 222
12
Buell/Girard, "Chemistry",Prentice Hall, NJ,
1994, 219
13
Acidity of Aqueous Solutions

• Acidity refers to H which differs from the
  acid if the acid is weak
• Acidity of solution is defined relative to H
  of water, 1.0 x 10-7 M
• Acidic H gt 1.0 x 10-7 M
• Neutral H 1.0 x 10-7 M (Water)
• Basic H lt 1.0 x 10-7 M

14
Acidity of Pure Water
http//gcsechemistry.com/aa8.htm
15
Acidity Expressed as pH

• pH is a logarithmic scale for expressing acidity
  of a solution
• pH - log10 H
• Acidic pH lt 7
• Neutral pH 7
• Basic pH gt 7

16
H
H 10 - pH
Tro, page 327
17
O.
Buell/Girard, "Chemistry", Prentice Hall, NJ,
1994, 225
18
Buell/Girard, "Chemistry",Prentice Hall, NJ,
1994, 225
19
Acid/Base Reactions

• Reaction of acid with a base produces water and a
  salt (ionic substance which contains the cation
  of base and anion of acid) - called
  neutralization
• NaOH(aq) HCl(aq) gt NaCl(aq) H2O (l) where
  (aq) denotes a solute in solution, (l) is a
  liquid. Others (g) is used for a gas and (s) is
  used for a solid

20
Bronsted-Lowry Definitions of Acids and Bases

• Acid is a proton (H) donor
• Base is a proton (H) acceptor
• The reaction of acid with a base is the transfer
  of the proton (H) from the acid to the base
• NH3(aq) HCl(aq) gt NH4Cl(aq)
• NH3 is Lewis base and HCl is Lewis acid

21
Bases in over-the-counter antacids
Buell/Girard, "Chemistry",Prentice Hall, NJ,
1994, 219
22
Precipitation Reaction
Reaction involving the formation of an insoluble
substance which separates from the solution
Silberberg, Chemistry, Mosby, MO, 1996, 146
23
Reduction/Oxidation Reactions (Redox)

• Oxidation is the loss or partial loss of
  electrons by an atom
• Reduction is the gain or partial gain of
  electrons by an atom
• Total gain/loss of e during redox Zn(s)
  Cu2 (aq) gt Zn2 (aq) Cu(s)
• Zn loses 2e (oxidation) and Cu2 gains 2e
  (reduction)

24
Redox Reactions Involving Partial Gain/Loss of
Electrons

• The formation of a covalent bond with a more
  electronegative element results in a partial loss
  of e by an atom (oxidation)
• The formation of a covalent bond with a less
  electronegative element results in a partial gain
  of e by an atom (reduction)

25
http//wine1.sb.fsu.edu/chm1045/notes/Bonding/Pola
rity/Bond05.htm
26
Example of Partial Gain/Loss of Electrons During
Redox

• N2(g) 3 H2(g) gt 2 NH3(g)
• N has formed a bond with less electronegative H -
  partial gain of e (reduction N has been reduced)
• H has formed a bond with the more electronegative
  N - partial loss of e (oxidation H has been
  oxidized)

27
Oxidizing and Reducing Agents

• Oxidizing agent is the reactant that provides the
  atom that is reduced
• Reducing agent is the reactant that provides the
  atom that is oxidized
• In the previous reaction, H2 is the reducing
  agent (provides H which is oxidized) and N2 is
  the oxidizing agent (provides N which is reduced)

28
Reactions on Primitive Earth

• Early redox reactions produced NH3, CH4, H2O,
  and CO2
• Early anhydride reactions produced H2CO3,
  Ca(OH)2, H3PO4 , HNO3
• Early precipitation reactions produced insoluble
  carbonates (CO32-), phosphates (PO43-), and
  sulfides (S2-)

See eNote10 for equations
29
Continued...

• Arrhenius neutralization reaction Ca(OH)2(aq)
  H2CO3(aq) gt CaCO3(s) 2 H2O(l)
• Bronsted proton transfer reaction that produces a
  substance that would later become a plant
  nutrient NH3(aq) HNO3(aq) gt
  NH4NO3(aq)