Transcript Predicting Products of Reactions

Drill #4B
2/10/15
Predict the products and balance
the equation for the following
double-replacement reaction:
Na2CrO4 (aq) + Ba(OH)2 (aq) →
Drill #3
2/10/15
• Translate and predict products for the
following reactants:
• calcium hydroxide + phosphoric acid
• FeCl3 + NH4OH
Answer
1 Na2CrO4 (aq) + 1 Ba(OH)2 (aq) →
2 NaOH (aq) + 1 BaCrO4 (s)
BaCrO4 is the precipitate (solid) – how do
we know this? Solubility Rules
Agenda
• Pass fwd 9-2 Practice Problems.
Drill # 4A
2/9/15
Write the balanced chemical equations for
the following:
 aluminum bromide + chlorine yield
aluminum chloride + bromine
 Potassium chlorate when heated yields
potassium chloride + oxygen gas
 Hydrogen + nitrogen monoxide yield water
+ nitrogen
Agenda
• Predicting Products
• Precipitation Reactions and Solubility
Rules
Lab on Wed
Predicting
Products of
Reactions
Synthesis Reactions:
A + B  AB
• Element + Element  Compound
– There are other forms, but for your test, it
will always be an ionic compound
• To predict the products of a synthesis
reaction, just cross the charges of the
elements
• Example:
– Li + Br2  ?
– Li + Br2  LiBr
– 2Li + Br2  2LiBr (balanced)
Synthesis Practice
• Mg + N2  ?
• Mg + N2  Mg3N2
• 3Mg + N2  Mg3N2
• Mn + Cl2  ? (Use Mn2+)
• Mn + Cl2  MnCl2 (already balanced)
• K + O2  ?
• K + O2  K2O
• 4K + O2  2K2O
Decomposition Reactions
AB  A + B
• Compound  Element + Element
– There are other forms, but for your test, we
will always end with two elements.
• To predict the product, just separate the
compound into elements.
DON’T FORGET THE
• Example:
DIATOMIC ELEMENTS!
– CaO  ?
– CaO  Ca + O2
– 2 CaO  2 Ca + O2
H2, N2, O2, F2, Cl2, Br2, I2
Decomposition Practice
• PbI2  ?
• PbI2  Pb + I2
(already balanced)
• Li2S  ?
• Li2S  Li + S
• Li2S  2 Li + S
• NH3  ?
• NH3  N2 + H2
• 2 NH3  N2 + 3 H2
• AlF3  ?
• AlF3  Al + F2
• 2AlF3  2Al + 3F2
Single Replacement Reactions
• Element + Compound 
New Element + New Compound
• 2 forms:
– A + BC  AC + B (A is a metal)
• OR
– X + YZ  YX + Z (X is a nonmetal)
Single Replacement Rxns.
Cont.
• You must use an Activity Series to
determine if there is a reaction.
– If the free metal is above the bonded metal on
the Metal Activity Series (on the back of your
Periodic Table), the free metal will take the
place of the bonded metal. (If it is below, then
NR – no reaction)
– If the free nonmetal is above the bonded
nonmetal on the Periodic Table, the free
nonmetal will take the place of the bonded
nonmetal. (If it is below, then NR.)
Single Replacement Practice
• Fe + CuSO4  ? (use Fe2+)
• Fe + CuSO4  FeSO4 + Cu (already balanced)
– Why? Fe is above Cu on the Activity Series
• Ca + HgO  ?
• Ca + HgO  CaO + Hg (already balanced)
– Why? Ca is above Hg on the Activity Series
Single Replacement Practice
• Ni + Mn2O3  ? (Use Ni2+)
• Ni + Mn2O3  NR (no need to balance!)
– Why? Ni is below Mn on the Activity Series
• Al + FeCl2  ?
• Al + FeCl2  Fe + AlCl3
– Why? Al is above Fe on the Activity Series
• 2 Al + 3 FeCl2  3 Fe + 2 AlCl3
Single Replacement Practice
• MnCl3 + F2  ?
• MnCl3 + F2  MnF3 + Cl2
– Why? F is above Cl on the Periodic Table
• 2 MnCl3 + 3 F2  2 MnF3 + 3 Cl2
• S + Na2O  ?
• S + Na2O  NR (no need to balance!)
– Why? S is below O on the Periodic Table
Double Replacement Reactions
AB + CD  AD + CB
• Compound + Compound 
New Compound + New Compound
• To predict, swap ion pairs and re-cross
charges.
• Example:
– Fe(OH)2 + H2SO4  ?
– Fe(OH)2 + H2SO4  FeSO4 + HOH (H2O)
– Fe(OH)2 + H2SO4  FeSO4 + 2 H2O
Double Replacement Practice
• KI + PbCl2  ?
• KI + PbCl2  KCl + PbI2
• 2 KI + PbCl2  2 KCl + PbI2
Combustion Reactions
CxHx + O2  CO2 + H2O
• Any reaction between a compound of
carbon and hydrogen (CxHx) and oxygen
will produce the same two products –
carbon dioxide and water!
• Example:
– CH4 + O2  ?
– CH4 + O2  CO2 + H2O
– CH4 + 2 O2  CO2 + 2 H2O
Combustion Practice
• C6H6 + O2  ?
• C6H6 + O2  CO2 + H2O
• 2 C6H6 + 15 O2  12 CO2 + 6 H2O
• C2H5OH + O2  ?
• C2H5OH + O2  CO2 + H2O
• C2H5OH + 3 O2  2 CO2 + 3 H2O
Precipitation Reactions
• No ionic compound is entirely insoluble in
water, however compounds of low
solubility can be considered insoluble for
most practical purposes.
• There are some general guidelines to help
predict whether a compound made of a
certain combination of ions is soluble.
Solubility Rules Table
 Use this table to determine if precipitation
will occur.
 Precipitation occurs when the attraction
between the ions is greater than the
attraction between the ions and
surrounding water molecules.
 Precipitate = solid
Assignment
Complete the “Double Replacement
Reactions and the Solubility Rules”
worksheet
Directions: use the solubility rules handout
to determine the correct phase for each
product
• Review WS