CHM
1025C Module Five Sample Answers Name:__ Answers ____
Part
H1 Double Replacement Reaction:
Neutralization/Gas Forming
Reactions 10 points
Given
the following Solubility Rules for Ionic Compounds:
Complete and balance the following precipitation
reactions using the above solubility table
(write no reaction if both
products are soluble or a covalent compounds is not formed)
1. First write the ions of the products:
Mg(OH)2 (s)
+ H2SO4 (aq) ------> Mg2+ SO42- +
H1+ OH 1-
Second write the balanced formulas of the products and then
balance the chemical equation:
Mg(OH)2 (s) +
H2SO4 (aq) ------> MgSO4
(aq) + 2 H2O
(l)
2. H3PO4
(aq) +
KOH (aq)
------> K1+ PO43- + H1+ OH1-
H3PO4 (aq)
+ 2
KOH (aq)
------> K3PO4 (aq) + 3 H2O (l)
3. NH4NO3
(aq) +
Ba(OH)2 (aq) ----> Ba2+ NO31- + NH41+ OH1-
2 NH4NO3 (aq) + Ba(OH)2
(aq) ----> Ba(NO3)2
(aq) + 2 NH4OH (d)
(d) means immediate
decomposes into ammonia and water
2 NH4NO3 (aq)
+ Ba(OH)2 (aq) ----> Ba(NO3)2 (aq) + 2 NH3
↑ + 2 H2O (l)
4. HBr (aq) +
Pb(CO3)2 (aq) -----> Pb2+ Br1- +
H1+ CO3
2-
2
HBr (aq) +
Pb(CO3)2 (aq) -----> PbBr2 ↓ + H2CO3
(d)
(d) means immediate
decomposes into Carbon Dioxide and water
2 HBr (aq) + Pb(CO3)2 (aq) -----> PbBr2 ↓ + CO2
↑ + H2O(l)
5. LiOH (aq) + H3PO4 (aq) ---> Li1+ PO43- + H1+ OH1-
3 LiOH
(aq) + H3PO4 (aq) ---> Li3PO4
(aq) + 3 H2O
(l)
When either H2CO3 or NH4OH
is formed as a product it immediately
decomposes thus demonstrating a gas
forming reaction. Most books
do not show the either H2CO3
or NH4OH as products, just the
decomposed products of the gases and
water as in the final answer.