Ch 4: Chemical Reactions and Aqueous Solutions

what do coefficients tell you?

in what proportions the reaction occurs

combination reaction

A + B → AB

decomposition reaction

AB → A + B

single replacement

A + BC → AC + B

double replacement

AB + CD → AC + BD

electrolyte

substances that, when dissolved in water, conduct electricity (water soluble)

strong electrolytes 

conduct a current very efficiently; completely dissociate in water 

examples of strong electrolytes

ionic compounds, strong acids, and strong bases 

weak electrolytes 

conduct a small current in aqueous solutions; partial dissociation 

examples of weak electrolytes

weak acids and weak bases

nonelectrolytes

do not permit current to flow; dissolved as molecules 

examples of nonelectrolytes

molecular compounds

precipitation reactions 

reactions in which at least one insoluble salt forms 

how are insoluble ionic compounds formed?

when two solutions of 2 ionic compounds are mixed and undergo a double-replacement

overall/total chemical equations

shows the complete formulas of the reactions and products

how are reactions involving electrolyte solutions best described?

as ionic equations

spectator ions

don’t participate in the reaction (whatever is not precipitate)

net ionic equation 

removal of spectator ions to leave just charged ions 

what are common strong acids?

• hydrochloric acid (HCl) 

• hydrobromic acid (HBr) 

• hydroiodic acid (HI)

• nitric acid (HNO₃) 

• perchloric acid (HClO₄) 

• chloric acid (HClO₃)

• sulfuric acid (H₂SO₄) 

which strong acids are monoprotic

• hydrochloric acid (HCl) 

• hydrobromic acid (HBr) 

• hydroiodic acid (HI)

• nitric acid (HNO₃) 

which strong acids are polyprotic?

• perchloric acid (HClO₄) 

• chloric acid (HClO₃)

• sulfuric acid (H₂SO₄) 

strong bases

• lithium hydroxide (LiOH)

• sodium hydroxide (NaOH)

• potassium hydroxide (KOH)

• calcium hydroxide (Ca(OH)₂)

• strontium hydroxide (Sr(OH)₂)

• barium hydroxide (Ba(OH)₂)

do weak acids and weak bases produce a reaction?

no

oxidation-reduction (redox) reactions

involve the transfer of electrons

oxidation states (oxidation numbers)

used to keep track of the electron transfer in redox reactions

oxidation 

• higher oxidation number (oxidize) 

• loss of electrons 

• reducing agent 

reduction 

• lower oxidation state (reduce) 

• gain of electrons 

• oxidizing agent 

oxidation state of an atom

0

oxidation state of a monatomic ion

the same as its charge

oxidation state of fluorine

-1

oxidation state of oxygen in compounds

-2

oxidation state of peroxides (O₂)

-1

oxidation state of hydrogen in covalent compounds

+1