Honors Chemistry
Chapter 11 Note Packet
(student’s edition)
Chapter 11 problems: 36, 40, 52, 54, 57, 67, 71, 72
Chapter 11 figures: All of the figures are important and Table 1
11.1 Describing Chemical Reactions
reactants ®
chemical equations describe
example – creation of hydrogen chloride:
H2 + Cl2 à
Say:
other example - creation of sodium chloride:
Na + Cl2 à
Say:
Showing Phases in Chemical Reactions:
gas = liquid = solid = aqueous
Ex1: NaCl(s) =
Ex2: NaCl(aq) =
Ex3: H2O(l) = (not aqueous - redundant)
other symbols: à (one arrow) = reactions
« (2 arrows) = reaction
D H = Change in
cat = (a substance that speeds up a reaction without being
in the reaction)
ppt = (solid - only found on side)
Balancing Chemical Equations: truly a trial and error process if there ever was one
Helpful hints:
1. 1 atom at a time
2. Balance atoms that appear only 1X per side first
3. Balance as whole units
4. Balance diatomic elements last
5. Save H + O for last
if this doesn’t succeed, try everything (particularly with combustion)
Showing Energy Changes in Equations:
endothermic -
A + B + heat àC DH is
exothermic -
A + B àC + heat DH is
Interpreting Chemical Equation - what do chemical equations really mean anyway?
H2O à H2 + O2 (not balanced)
H2O à H2 + O2 (equal)
atoms à atoms + atoms (equal)
g à g + g (equal)
moles à moles + mole (not equal - doesn’t have to)
11.2 Types of Chemical Reactions
5 types - synthesis, decomposition, combustion, single replacement, double replacement
remember - first you’ve got to find the right products, then you gotta balance
1. Synthesis ( direct combination ) - needs to happen
general formula (element + element): A + B à AB
Ex1: Ba + S à
Ex2 Mg + Cl2 à
Ex3: Al + 3Cl2 à
Ex4: Na + O2 à
2. Decomposition (analysis) - needs to happen (usually )
general formula (molecule + element): AB à A + B
Ex5: FeCl3 à +
Ex6: HgO à +
Ex7: MgSO4. 7 H2O à +
(hydrate)
3. Combustion - the reaction of hydrocarbons and oxygen to yield and
.
general formula (“CHO”): CxHy + O2 à CO2 + H2O
Ex8: combustion of CH4
Ex9: combustion of C3H8
Ex10: combustion of C4H10
Ex11: combustion of C2H5OH
4. Single Replacement - take place in solutions and need energy
a) Type 1: ions switch
general formula (molecule + element):
AB + M à MB + A
Ex12: HI + Mg à +
Ex13: AlCl3 + Ca à +
Ex14: Ca + HOH à +
b) Type 2: ions switch
general formula (molecule + element):
AB + X à AX + B
Ex15: NaCl + F2 à +
Ex16: BaS + O2 à +
5. Double Replacement - again - aqueous solution - little energy - usually forms one
soluble ionic product (aka - aqueous) and either a ppt,
water, or a gas that bubbles out of water
general formula (molecule + molecule):
AB + CD à CB + AD
Ex17:
FeCl3 + NaOH à +
Ex18:
H2SO4 + NaOH à +
Ex19:
NH4Cl + NaOH àNH3(g) + H2O(l) + NaCl(aq)
Hey, some reactions happen and some don’t.
For synthesis, combustion, and decomposition, we will assume they all given
sufficient activation energy (Ea).
For single replacement, use the !
Ex20: Ca + H2O à
Ca + H(OH) à +
Ex21: Al + H2O à
Al + H(OH) à
Ex22: Al + HI à +
Ex23: Cu + HI à
Rules for the single replacement activity series:
1. Any single element above an element in a compound will it.
2. The top 5 elements react with .
3. Metals above H react with (molecules that start with H – not water).
4. The nonmetal reactivity series is ...
For double replacement reactions, use a solubility table and the following rules:
1. If one of the products formed is water, the reaction .
2. If a gas is formed, the reaction .
3. If an insoluble product forms ( ), the reaction (actually a reaction may happen when two soluble products form, but it doesn’t go to completion and is not directly observable).
Ex24: Na2CrO4 + KCl à
Ex25: FeCl3 + KOH à +
Note: precipitate symbols include
11.3 Reactions in Aqueous Solution
Ions in solutions for aqueous solutions.
Ionic compounds are .
When you put them in water, they :
Ex1: NaBr(s) + H2O(l) à
Ex2: MgCl2(s) + H2O(l) à
Also happens with some molecular substances - particularly :
Ex3: HCl(g) + H2O(l) à
Ex4: H2CrO4(s) + H2O(l) à
Writing Ionic Equations
so far we’ve looked at molecular equations
now it’s time for ionic equations - show what happens to the ions in a reaction
Ex1:
(“molecular” equation) Fe(s) + HF(aq) à
(total ionic)
(net ionic)
spectator ion =
Spectator ions are ions that undergo in a chemical reaction.
Ex2:
(“molecular” equation) H2SO4(aq) + NaOH(aq) à
(total ionic)
(net ionic)
spectator ions =
Conservation of Charge - charges must in a chemical reaction.
NIB Solubility Trends
Cations - very soluble -
very insoluble-
Anions - very soluble -
for monotomics
very insoluble
sulfides
general trend:
As size decreases, solubility .