Precipitation Reactions
2-4:
Precipitation
Reactions
1.
Start
Virtual
ChemLab
and
select
Precipitation
Reactions
from
the
list
of
assignments.
The
lab
will open
in
the
Inorganic
laboratory.
2.
React
each
of
the
cations
(across
the
top)
with
each
of
the
anions
(down
the
left)
according
to
the
data table
using
the
following
procedures:
Data
Table
AgNO
3
(Ag
+
)
Pb(NO
3
)
2
(Pb
2+
)
Ca(NO
3
)
2
(Ca
2+
)
Na
2
CO
3
(CO
3
2
-
)
A
Turned to a cloudy
peach color
F
Turned a milky white
color
K
Turned a milky
white color
Na
2
S
(S
2
-
)
B
Turned a cloudy black
color
G
Turned a cloudy
black color
L
No Reaction
NaOH
(OH
-
)
C
Turned a cloudy
bubbly brown color
H
No Reaction
M
Turned a milky
white color
Na
2
S0
4
(SO
4
2
-
)
D
No Reaction
I
Turned a milky white
color
N
No Reaction
NaCl
(Cl
-
)
E
Turned a milky white
color
J
Turned a milky white
color
O
No Reaction
a.
Enter
the
stockroom
by
clicking
inside
the
Stockroom
window.
Once
inside
the
stockroom,
drag
a
test
tube
from
the
box
and
place
it
on
the
metal
test
tube
stand.
You
can
then
click
on
the
bottle
of
Ag
+
ion
solution
on
the
shelf
to
add
it
to
the
test
tube.
Click
Done
to
send
the
test
tube
back
to
the
lab.
Click
on
the
Return
to
Lab
arrow.
b.
Place
the
test
tube
containing
the
Ag
+
solution
in
the
metal
test
tube
stand.
Click
on
the
Divide
button
on
the
bottom
(with
the
large
red
arrow)
four
times
to
make
four
additional
test
tubes containing
Ag
+
.
With
one
test
tube
in
the
metal
stand
and
four
others
in
the
blue
rack,
click
on
the Na
2
CO
3
bottle
on
the
reagent
shelf
and
observe
what
happens
in
the
window
at
the
bottom
left. Record
your
observation
in
the
table
above.
If
the
solution
remains
clear,
record
NR
for
no
reaction.
Drag
this
test
tube
to
the
red
disposal
bucket
on
the
right.
c.
Drag
a
second
tube
from
the
blue
rack
to
the
metal
stand.
Add
Na
2
S,
record
your
observations
and
discard
the
tube.
Continue
with
the
third,
fourth
and
fifth
tube,
but
add
NaOH,
Na
2
SO
4
,
and
NaCl
respectively.
Record
your
observations
and
discard
the
tubes.
When
you
are
finished,
click
on
the
red
disposal
bucket
to
clear
the
lab.
d.
Return
to
the
stockroom
and
repeat
steps
a-c
for
five
test
tubes
of
Pb
2+
and
Ca
2+
.
Record
your
observations
in
the
data
table.
If
no
precipitate
forms
write
NR
for
no
reaction.
3.
What
happens
in
grid
space
d?
What
other
reactions
give
similar
results?
Is
it
necessary
to
write
an
equation
when
no
reaction
occurs?
Explain:
When AgNO
3
(Ag
+
) was combined with Na
2
S0
4
(SO
4
2
-
) there was no reaction. This also
occurred when Pb(NO
3
)
2
(Pb
2+
) was combined with NaOH
(OH
-
). Also when Ca(NO
3
)
2
(Ca
2+
) was combined with Na
2
S
(S
2
-
) and with Na
2
S0
4
(SO
4
2
-
) and finally with NaCl
(Cl
-
). So
there’s no need to write an equation.
4.
Write
balanced
equations
for
all
precipitation
reactions
you
observed.
a.
2AgNO
3 +
Na
2
CO
3
=> 2NaNO
3 + AgCO3
b.
2AgNO
3 +
Na
2
S
=> 2
NaNO
3 + Ag2S
c.
AgNO
3 +
NaOH => NaNO
3 + AgOH
d.
N/R
e.
AgNO
3 +
NaCl
=> NaNO
3 + AgCI
f.
Pb(NO
3
)
2 +
Na
2
CO
3
=> 2NaNO
3 +
PbCO3
g.
Pb(NO
3
)
2 +
Na
2
S => 2NaNO
3 +
PbS
h.
N/R
i.
Pb(NO
3
)
2 +
Na
2
S0
4
=> 2NaNO
3 +
PbSO4
j.
Pb(NO
3
)
2 +
2NaCl => 2NaNO
3 +
PbCl2
k.
Ca(NO
3
)
2 +
Na
2
CO
3
=> 2NaNO
3 +
CaCO3
l.
N/R
m.
Ca(NO
3
)
2 +
2NaOH => 2NaNO
3 +
Ca(OH)2
n.
N/R
o.
N/R
5.
Write
balanced
net
ionic
equations
for
all
precipitation
reactions
you
observed.
a.
2Ag
+
+ CO
3
2-
=> AgCO
3
(s)
b.
2Ag
+
+ S
2-
=> Ag
2
S (s)
c.
Ag
+
+ OH
-
=> AgOH (s)
d.
N/R
e.
Ag
+
+ Cl
-
=>
AgCl (s)
f.
Pb
2+
+ CO
3
2-
=>
PbCO
3
(s)
g.
Pb
2+
+ S
2-
=> PbS (s)
h.
N/R
i.
Pb
2+
+ SO
4
2-
=> PbSO
4
(s)
j.
Pb
2+
+ 2Cl
-
=>
PbCl
2
(s)
k.
Ca
2+
+ CO
3
2-
=> CaCO
3
(s)
l.
N/R
m.
Ca
2+
+ 2OH
-
=> Ca(OH)
2
(s)
n.
N/R
o.
N/R