Lab 11
pdf
School
Rutgers University *
*We aren’t endorsed by this school
Course
171
Subject
Chemistry
Date
Dec 6, 2023
Type
Pages
15
Uploaded by SuperFlag12639
ENTHALPY
OF
FORMATION
OF
AMMONIUM
SALTS
BACKGROUND
INFORMATION
There
are
a
very
large
number
of
chemical
reactions
that
have
never
been
investigated.
There
may
be
good
reasons
for
not
performing
certain
chemical
reactions.
For
example,
some
reactions
may
pose
great
risks
to
the
environment
or
to
living
organisms.
Other
reactions
may
be
too
costly
in
terms
of
time
or
money.
Studying
the
chemical
reactivity
of
diamonds
would
certainly
be an
expensive
undertaking.
Fortunately,
there
are
methods
that
allow
us
to
study
certain
aspects
of
chemical
reactions
without
ever
having
to
perform
the
reactions.
Hess’s
Law
(also
known
as
the
Law
of
Constant
Heat
Summation)
is
an
example
of
a
method
that
allows
chemists
to
study
the
thermodynamics
of
a
chemical
reaction
without
having
to
perform
the
reaction
itself.
Germain
Henri
Hess
discovered
this
fundamental
law
of
nature
in
1840
while
studying
the
heat
evolved
when
acids
and
bases
are
mixed
with
water.
Hess’s
Law
states
that the
enthalpy
change
(AH)
of
individual
steps
in
a
process
can
be
added
or
subtracted
to
determine
the
overall
enthalpy
change
of
the
process.
Hess’s
Law
is
a
direct
consequence
of
the
First
Law
of
Thermodynamics,
which
requires
that the
enthalpy
change
of
a
reaction
be
the
same
regardless
of
the
reaction
pathway
that
leads
from
reactants
to
products.
Thus,
the
net
amount
of
heat
liberated
or
absorbed
in
a
chemical
process
is
the
same,
regardless
of
whether
the
process
is
performed
in
one
step
or
multiple
steps.
Because
of
the
additive
property
of
AH,
we
can
use
a
standard
set
of
reactions
from
which
we
can
gener-
ate
any
other reaction.
All
we
have
to
do
is
add
the
enthalpies
of
these
standard
reactions
and
we
have
the
enthalpy
of
our
reaction
of
interest.
The
standard
reactions
we
use
are
called
formation
reactions
and
the
enthalpies
are
enthalpies
of
formation
symbolized
by
AHf.
A
formation
reaction
has
one
single
product:
one
mole
of
the
compound.
The
reactants
are
elements
in
their
standard
states.
Thus,
on
paper,
we
can
decompose
any
compound
to
its
elements
(AH
=
—AHy
and
then
take
those
elements
and
rearrange
them
into
the
product
compounds
(AH
=
AH?).
This
leads
to
the
equation
1.
AH°=
Y
AH?-
Y,
AH}
(1)
Product
Reactants
This
process
for the
reaction
3C,H,
—
Cg¢Hg
is
shown
in
figure
1.
In
today’s
experiment,
you
will
use
Hess’s
Law
to
determine
the
enthalpy
change
(AH)
of
a
chemical
reaction
that
cannot
be
easily
measured
by
experimental
methods.
This
reaction
is
represented
by
equa-
tion
(2).
From
General
Chemistry,
2nd
Edition
by
Department
of
Chemistry,
University
of
North
Carolina
at
Wilmington.
Copyright
©
2004
by
University
of
North
Carolina
at
Wilmington.
Reprinted
by
permission
of
Kendall/Hunt
Publishing
Company.
115
116
LAB
11:
ENTHALPY
OF
FORMATION
OF
AMMONIUM
SALTS
6C
+
3H,
3C,H,
Enthalpy
CeHe
FIGURE
1.
Enthalpy
of
conversion
of
-
acetylene
to
benzene.
%Nz(g)
+
2H,(g)
+
%Clz(g)
—
NH,CI(s)
or
Nx(g)
+
2H,(g)
+
%
O,(g)
-
NH4,NOs(s)
AH,
(2)
You
will
determine
the
value
of
AH
for
this
reaction
by
measuring
the
enthalpy
changes
of
two
related
chemical
reactions.
These
reactions
are
represented
by
equations
(3)
and
(4)
below.
NH;(aq)
+
HCl(aq)
-
NH,Cl(aq)
or
NHs(aq)
+
HNO;(aq)
-
NH;NOs(aq)
AH,
(3)
NH,Cl(aq)
—
222
5
NH,CI(s)
or
NH4;NO;(aq)
—:°
y
NH,NO;
(s)
AH;
(4)
Equation
(2)
can
be
obtained
by
adding
equation
(3)
to
equation
(4)
along
with
the
enthalpies
of
forma-
tion
of the
aqueous
and
ammonia
(shown
in
equations
(5)
and
(6),
below).
|
1
3
Hy(g)
+
-
Cla(g) —
205
HCl(aq)
Ha(g)
+
>
N28)
+
5
0:(8)
—
%0
s
HNOs(ag)
AH;
(5)
1
3
7
Na(g)
+
5
Ha(g)
—=2
5
NHs(aq)
AH,
(6)
We
simply
add
the
enthalpies
for
(3),
(5)
and
(6)
together
with
the
reverse
of
(4)
AH})
=
AH3
+
AH4
+
AHS
<+
AH6
(7)
The
enthalpies
for
(5)
and
(6)
are
readily
available
from
the
literature.
Equation
(1)
can
be
obtained
by
adding
equation
(2)
to
the
reverse
of
equation
(3).
If
we
reverse
equa-
tion
(3),
we
must
also
change
the
sign
of
the
enthalpy
change
for
the
reaction.
According
to
Hess’s
Law,
if
we
add
the
equations
for
two
reactions
together,
we
can
also
add
their
enthalpy
changes
together.
Thus,
the
enthalpy
change
for
reaction
(1)
is
simply
the
sum
of
the
enthalpy
change
for
reaction
(2)
and
the
reverse
of
reaction
(3).
AH,
=
AH,
+
(-AH;)
(8)
LAB
11:
ENTHALPY
OF
FORMATION
OF
AMMONIUM
SALTS
117
To
determine
the
enthalpy
changes
(AH,
and
AH3)
of
reactions
(2)
and
(3),
you
must
measure
the
heat
(q)
released
by
each
reaction.
You
will
do
this
using
the
same
techniques
and
concepts
you
used
in
the
experiment
on
calorimetry.
(You
might
want
to
review
the
Introduction
to
Calorimetry.)
Recall
that
the
heat
exchanged
in
a
process
can
be
calculated
from
the
following
equation
g=cxmxAT
9)
where
m
is
the
mass
of
the
substance
in
grams,
the
specific
heat,
¢,
of
the
substance
is
expressed
in
units
of
J/ge°C,
and
AT
is
the
temperature
change
the
substance
undergoes
(Tfipa
—
Tiniial)-
Some
heat
will
be
lost
through
the
walls
and
lid
of
the
calorimeter.
A
correction
term
C,
=
15
J/K
will
be
used
to
estimate
this
loss.
Our
corrected
relationship
between
heat
and
temperature
becomes:
g
=
(¢
x
m
+
15)AT.
The
specific
heat
capacities
can
be
found
in
Table
2.
Gwater
=
(418
J/g.oc)(mwater)(ATwater)
(10)
The
heat
gained
by
the
water
is
equal
in
magnitude
by
opposite
in
sign
to
the
heat
lost
by
the
reaction.
Therefore,
we
can
calculate
ge,cion
from
the
following
relationship.
Yreaction
=
—Ywater
(1 1)
Finally,
the
enthalpy
change
of
each
reaction,
AH,.,.ion,
can
be
determined
by
dividing
the
heat
lost
by
the
reaction
(Greaciion)
by
the
number
of
moles
of
product
formed
(either
NH,Cl(aq)
or
NH;NOs(aq)).
For
reaction
(2),
this
calculation
takes
the
following
form.
AH,
=
4
(12)
moles
NH,Cl
or
NH,NO;
PROCEDURE
Caurion:
Wear
departmentally
approved
eye
protection.
If
you
are
found
without
the
eye
protection,
penalty
will
be
imposed
without
warning.
Gloves
and
proper
attire
must
be
worn
during
this
experiment.
This
experiment
will
be
performed
in
pairs.
The
write-up,
calculations,
graphing,
etc.,
must
be
done
totally
independently.
A
series
of
two
experiments
will
be
performed.
Assume
the
calorimeter
constant,
Cec,
to
be
157
K.
Part
A.
Determination
of
the
enthalpy
of
reaction
of
aqueous
ammonia
with
a
strong
acid
(HCI
or
HNO;)
assigned
by
the
instructor.
Part
B.
Determination
of
the
enthalpy
of
solution
of
the
ammonium
salt
of
the
acid
used
in
Part
A
(NH4C1
or
NH4NO3).
In
addition
to
reagents,
the
equipment
needed
is:
two
6-0z
pressed
Polystyrene
cups
(and
one
cup
lid),
a
150-mL
beaker,
two
100-mL
graduated
cylinders,
and
one
thermometer.
Keep
the
cups
together,
as
though
they
were
glued
together.
You
need
2
cups
for
the
additional
insulation.
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
118
LAB
11:
ENTHALPY
OF
FORMATION
OF
AMMONIUM
SALTS
Solution
temperature
as
a
function
of
time
will
be
recorded
on
the
data
sheet.
In
addition
to
recording
the
data,
a
temperature-time
plot
on
graph
paper
should
be
prepared;
this
can
be
done
while
the
data
are
being
collected.
The
temperature
should
be
plotted
on
the
y-axis
and
the
time
in
minutes
on
the
x-axis.
The
T
observed
will
be
between
7
and
14°
for
Part
A
and
between
—1
and
—6°
for
Part
B.
The
scale
units
on
the
y-axis
should
be
selected
so
that
all
points
can
be
plotted
on
scale;
the
scale
units
on
the
x-axis
should
cover
the
range
0—20
minutes.
The
procedure
is
essentially
the
same
for
both
parts:
1.
Rinse
one
Polystyrene
cup
and
beaker
with
distilled
water
and
wipe
dry
with
a
clean
piece
of
absorbent
paper.
Nest
it
in
the
other
cup
(see
figure
2).
Clean
a
beaker
with
distilled
water
and
wipe
dry
with
absorbent
paper.
Place
the
thermometer
through
the
lid
of
the
cup
with
the
rubber
ring
over
the
hole
set
so
that the
thermometer
will
not
touch
the
bottom
of
the
cup
when
the
lid
is
placed
on
the
cup.
Do
not
clamp
the
thermometer
to
the
ring
stand.
They
are
fragile
and
will
likely
break
if
clamped.
2.
Using
graduated
cylinders,
measure
solution
1
(see
Table
1)
into
the
cup and
(except
in
Part
B)
mea-
sure
solution
2
into
the
beaker.
Record
the
concentrations
of
the
solutions
used
on
the
Data
Sheet.
Note:
Calculate
the
concentration
of
the
ammonium
salt—NH,C]
or
NH,NO;—formed
in
the
reaction
of
Part
A.
Determine
the
mass
of
salt
in
100
mL
of
solution;
weigh
out
that
amount
of
salt
and
use
in
place
of
solution
2
in
Part
B.
3.
Check
the
temperature
of
solution
1.
Assume
the
temperature
of the
two
solutions
before
mixing
is
essentially
the
same.
Record
the
temperature
of
solution
1
at
1-minute
intervals
for
5
minutes.
4.
After
5
minutes
of
temperature
readings,
pour
solution
2
into
the
calorimeter
cup.
Immediately
swirl
the
cup
gently
to
mix
the
solution
well.
Record
the
time
of
mixing.
(Never
use
a
thermometer
as
a
stirring
rod!)
Continue
to
record
the
temperature
at
1-minute
intervals
for
10
minutes.
Do
one
determination
of
the
temperature
change
for
each
part
of
the
experiment.
Lid——>»
"
\
/4—
Inner
Cup
Thermometer
<«—
Outer
Cup
FIGURE
2.
Nested
polystyrene
cup.
LAB
11:
ENTHALPY
OF
FORMATION
OF
AMMONIUM
SALTS
119
TABLE
1
REAGENTS
TO
BE
USED
Part
A
B
Solution
1
50.0
mL
acid
(2.00M
HCI
or
2.00M
HNO;)
100.0
mL
distilled
water
Solution
2
50.0
mL
2.05M
NH;
See
Note,
p.
114
CALCULATIONS
Study
carefully
the
calculations
for
NH
Br
at
the
end
of
this
section.
1.
Find
the
temperature
change
AT
from
the
temperature-time
plots
by
extrapolating
the
plotted
data
to
the
time
of
mixing,
reading
the
initial
and
final
temperatures,
and
taking
the
temperature
change
for
each
determination.
See
figure
3
for
an
example.
Use
good
graphing
technique.
Data should
take
up
about
2/3rd
of
the
paper.
The
extrapolation
should
not
run
off
the
top
or
the
bottom
of
the
page.
Graph
should
have
a
title
and
axes
should
be
labeled.
Origin
does
not
need
to
be
(0,
0).
2.
Use
the
calorimeter
constant,
C,
of
15
J/K
for
the
calculation.
3.
Use
the
data
from
Part
A
and
the
calorimeter
constant
to
calculate
the
enthalpy
of
neutralization
of
NH;
and
the
assigned
acid.
4.
Use
the
data
from
Part
B
to
compute
the
enthalpy
of
solution
of
the
ammonium
salt.
5.
Use
the
results
for
the
enthalpy
of
neutralization
and
the
enthalpy
of
dissolution,
along
with
the
liter-
ature
values
of
AHy
for
NH;(aq)
and
the
assigned
acid
(given
in
Table
3)
to
compute
the
enthalpy
of
formation
of
the
ammonium
salt.
AT
=104K
25
T
(°C)
-
FIGURE
3.
Plot
of
temperature-time
0
5
10
15
data
showing
determination
of
AT.
Time
(min)
120
LAB
11:
ENTHALPY
OF
FORMATION
OF
AMMONIUM
SALTS
Typical
Calculations
for
NH,Br
Part
A
AT=119K,
d=1018g/mL
C=3911J/gK,
MM.
=97.8
g/mol
Mass
of
solution
=
100
mL
x
1.018
g/mL
=
101.8
g
Cs (heat
capacity
of the
solution)
=
101.8
g
x
3.91
J/g
K
=398
J/K
AH,;
=
—(Cs
+
C))AT
=—-(398
J/K
+
15.0
J/K)11.9
K
=-4915J
=-4915kJ
Students
mixed
50
mL
of
2.00M
acid
with
50.00
mL
of
2.05M
base,
1.e.,
0.100
mol
of the
reactants
were
used.
Therefore,
the
measured
AH,
is
for
0.100
mol
of
product
formed.
molar
AH,
=
—-4.915
kJ/
0.100
mol
=
—49.2
kJ/mol
Part
B
TABLE
2
MOLECULAR
WEIGHTS,
HEAT
CAPACITIES,
AND
DENSITIES
OF
SOLUTIONS
Molecular
wt.
Concentration
Sp.
heat
capacity”
density”
Solute
g
mol™
mol
L™
Jg'
K
gmL™
NH,Cl
53.49
1.00
3.93
1.013
NH,NO;
80.04
1.00
3.90
1.029
H,O
18.02
—
4.18
0.997
At
25°C
TABLE
3
ENTHALPIES
OF
FORMATION
AT
25
°C®
Reaction
AH?
kJ
mole™
INL(2)
+
2Hy(2)
+
—=2
5
NH;(ag,
2.0M)
—80.7
JHa(g)
+
3Cly(g)
—=2
5
HCl(aq,
2.0M)
~164.7
JHy(2)
+
3Nx(2)
+
50,(g)
—22
5
HNO;
(aq,
2.0M)
~206.0
Ha(g)
+305(g)
=
H0()
-285.8
*
“Selected
Values
of
Chemical
Thermodynamic
Properties,”
Circular
500,
National
Bureau
of
Standards,
Washington,
D.C.,
1961
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
LAB
11:
ENTHALPY
OF
FORMATION
OF
AMMONIUM
SALTS
121
From
Data
Sheet
1,
the
number
of
moles
of
the
product
formed
is
0.100
mol.
Therefore,
the
mass
of
the
NH,Br
used
to
measure
the
enthalpy
of
dissolution
is:
97.9
g/mol
x
0.100
mol
=
9.79
g.
=-3.5
K
Mass
of
solution
=
100
mL
H,O
x
1
g/mL
+9.79
g
NH,Br=109.79
g
Cs=109.79
g
x
3.91
J/g
K=429
J/K
AH,
=
—(429
J/K
+
15.0
J/K)(-3.5
K)
=1.6
x
10’J
=106kl
molar
AH,
=
16
kJ/mol
Calculation
of
AH?
of
NH,Br(s)
%N2(g)
4
3
H,(g)
"
5
NH;(aq)
AH,
=
-80.7
kJ/mol
=
Hz(g)
+
—
Brz(l)
+
—
3
HBr(aq)
AH,
=
—174
kJ/mol
NH;(aq)
+
HBr(aq)
——>
NH
Br(aq)
AH;
=-42.9
kJ/mol
(from
Part
A)
NH,Br(aq))
—°
5
NH,Br(s)
AH4
=
—16
kJ/mol
(from
Part
B)*
Sum
up
all
four
equations
|
3
|
o
Na(E)
+5
Hylg)
+-
Bry(l)
—
NH,Br(s)
AH?[NH,Br(s)]
=
AH,
+
AH,
+
AH;
+
AH,
=
—80.7
+
(~174)
+
(-42.9)
+
(~16)
=
-320
kJ/mol
*
The
sign
is
different
from
Part
B;
since
the
equation
is
reversed.
NAME
SECTION
LOCKER
INSTRUCTOR
PRE-LABORATORY
ASSIGNMENT
1.
A
thermometer
placed
in
a
solution
undergoing
a
chemical
reaction
indicates
an
increase
in
tempera-
ture
as
the
reaction
proceeds.
Is
this
reaction
endothermic
or
exothermic?
Describe
if
heat
energy
is
lost
or
gained
from
the
reaction
(the
system)
to
the
surroundings.
What
is
the
sign
of
the
enthalpy
change
(AH)
of
this
reaction?
2.
A
student
performs
a
reaction
and
determines
the
enthalpy
change
(AH)
to
be
31.4
kJ.
Will
the
tem-
perature
of
the
surrounding
solution
increase
or
decrease
as
a
result
of
this
chemical
process?
3.
If
you
hold
3
grams
of
ice
in
your
hand
at
room
temperature,
your
hand
will
become
cold.
(a)
Is
the
reaction
H,O
(s)
=
H,O
(/)
endothermic
or
exothermic?
(b)
In
which
direction
does
heat
flow?
LAB
11:
ENTHALPY
OF
FORMATION
OF
AMMONIUM
SALTS
123
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
CHEMICAL
HAZARD
AWARENESS
FORM
NAME:
RUID:
SECTION:
EXPERIMENT:
In
the
box
below,
list
each
chemical
you
will
be
using
in
the
experiment
and
the
appropriate
handling
precautions
for
that
chemical.
For
example:
acetone
(volatile
and
flammable)—avoid
inhaling
and
open
flames
124
LAB
11:
ENTHALPY
OF
FORMATION
OF
AMMONIUM
SALTS
NAME
SECTION
LOCKER
INSTRUCTOR
COVER
SHEET
ENTHALPY
OF
FORMATION
OF
AMMONIUM
SALTS
Purpose:
To
determine
the
heat
of
formation
of
an
ammonium
salt.
Procedure:
The
procedure
for
this
experiment
was
followed
as
in
this
experiment
except
(list
all
changes
in
procedure)
Results:
Calorimeter
Constant
Name
of
partners
Name
of
acid
Moles
of
acid
NEUTRALIZATION
DISSOLUTION
AT
=
AT
=
AHC.
AH
g
AHy
for
Conclusions:
LAB
11:
ENTHALPY
OF
FORMATION
OF
AMMONIUM
SALTS
125
NAME
SECTION
DATA
SHEET
Name
of
partner
LOCKER
INSTRUCTOR
Part
A:
Enthalpy
of
Neutralization
Part
B:
Enthalpy
of
Dissolution
[
I=
M
Salt
[NH;]
=
M
mass
g
Moles
TEMPERATURE-TIME
DATA
time,
min
temp.
HA,
°C
time,
min
temp.
H,O0,
°C
0
0
1
1
2
2
3
3
4
4
mix
mix
6
6
7
7
8
8
9
9
10
10
11
11
12
12
13
13
14
14
15
15
Calculation
of
Enthalpy
of
Neutralization
temperature
change,
AT,
°C
mass
of
solution,
g
solution
heat
capacity,
Cg,
J
i
AH,,J
molar
enthalpy
of
reaction
Calculation
of
Enthalpy
of
Dissolution
temperature
change,
AT,
°C
mass
of
solution,
g
solution
heat
capacity,
Cg,
J
K™
AH,,J
molar
enthalpy
of
dissolution
126
LAB
11:
ENTHALPY
OF
FORMATION
OF
AMMONIUM
SALTS
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
NAME
SECTION
LOCKER
INSTRUCTOR
LAB
11:
ENTHALPY
OF
FORMATION
OF
AMMONIUM
SALTS
127
NAME
SECTION
LOCKER
INSTRUCTOR
128
LAB
11:
ENTHALPY
OF
FORMATION
OF
AMMONIUM
SALTS
NAME
SECTION
LOCKER
INSTRUCTOR
POST-LABORATORY
QUESTIONS
1.
Write
a
balanced
equation
for
the
formation
of
CO,(g)
from
C(s)
and
O,(g).
Calculate
the
enthalpy
change
for
this
reaction
using
the
following
data
(at
25°C):
C(s)
+
%
Oy(2)
——3
CO(g)
AR
=
ITLKT
CO(g)
+
%
0x(2)
——>
COA(2)
AH
=
-394
kJ
Is
this
reaction
endothermic
or
exothermic?
2.
a.
Explain
how
AT
would
be
affected
if
a
greater
amount
of
surrounding
solvent
(water)
is
used,
assuming
the
mass
of
salt
remains
constant?
b.
Explain
how
¢.cion
Would
be
affected
if
a
greater
amount
of
surrounding
solvent
(water)
is
used?
Explain.
3.
If
the
following
enthalpies
are
known:
A+2B—52C+D
AH
=-95Kk]J
B+X—
5C
AH
=
+50
kJ
What
is
AH
for
the
following
reaction?
A—>52X+D
LAB
11:
ENTHALPY
OF
FORMATION
OF
AMMONIUM
SALTS
129
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
Related Documents
Related Questions
The previous answer I was given was incorrect. Please be sure of your information. Read the question thoroughly and explain. Thank you.
arrow_forward
Anna was asked to identify and explain if the equation CO2 (l) → CO2 (g) was an endothermic or exothermic reaction. However she got it wrong. What is her error and what should the answer have been?
Anna's statement: The equation is an exothermic reaction because the energy is released from liquid CO2 to the surroundings to become gaseous CO2 causing the molecules to slow down.
arrow_forward
For the reaction 2N2O5(g) ® 4NO2(g) + O2(g), the following data were collected.
t (minutes)
[N2O5] (mol/L)
0
1.24 x 10–2
10
0.92 x 10–2
20
0.68 x10–2
30
0.50 x 10–2
40
0.37 x 10–2
50
0.28 ´ 10–2
70
0.15 ´ 10–2
The initial rate of production of NO2 for this reaction is approximately:
A)
6.4 x10–4 mol/L • min
B)
3.2 x10–4 mol/L • min
C)
1.24 x 10–2 mol/L • min
D)
1.6 x 10–4 mol/L • min
E)
none of these
arrow_forward
20. Dissolving the salt potassium nitrate in water is an endothermic reaction. What would be
observed if potassium nitrate was dissolved in water?
a) The water would get very hot.
b) The water would get colder.
c) The salt would float to the top of the water.
d) Bubbles of hydrogen gas would be produced.
arrow_forward
Part IV
Cabbage Juice Indicator
Chop cabbage into small pieces until you have about 2 cups of chopped
cabbage. Boil for at least ten minutes to allow time for the color to leach out of
the cabbage. Allow it to cool for 15 min
• Filter out the plant material to obtain a red-purple-bluish colored liquid.
1. Add 1-2 drops of cabbage juice into a small bowl
2. Add 3-5 drops of vinegar into the bowl with the cabbage juice
3. Observe
Is this a chemical change or physical change? Explain?
Store the excess cabbage juice in your refrigerator, you will need them for future
experiments.
arrow_forward
The U.S. is one of several countries committed to reaching “net-zero” carbon emissions by 2050. This means that by 2050, all carbon dioxide emissions must be matched by the amount of carbon dioxide removed from the air. Why is it essential for all countries in the world to meet carbon reduction commitments like this
arrow_forward
In experiment #7, you observed the formation of carbon dioxide by reacting baking soda with vinegar. Why was it not possible to relight the candle?
A. Carbon dioxide is heavier than air so it stays in the beaker preventing the candle from relighting.
B. Carbon dioxide is lighter than air so it escaped from the beaker and the candle should have relit.
C. Carbon dioxide is heavier than air so it stays in the beaker and the candle should have relit.
D. Carbon dioxide is lighter than air so it escaped from the beaker preventing the candle from relighting.
arrow_forward
Suppose a pair of chemical compounds A and B can react in two different ways:
A+B → C
Reaction 1 gives product C.
A+B → D
Reaction 2 gives product D.
The following facts are known about the two reactions:
●
Reaction 1 is endothermic and Reaction 2 is exothermic.
• If a reaction vessel is charged ("filled") with A and B, then at first C is produced faster than D.
Use these facts to sketch a qualitative reaction energy diagram for both reactions.
Note: because these sketches are only qualitative, the energies don't have to be exact. They only have to have the right relationship to each other. For exam
if one energy is less than another, that fact should be clear in your sketch.
Reaction 1
Reaction 2
energy
energy
reaction coordinate
A + B
A + B
reaction coordinate
D
arrow_forward
A scientist wants to perform a reaction in a vacuum chamber to control the experiment as much as possible and to prevent other variables from impacting the reaction. The scientist is trying to determine if the reaction is endothermic or exothermic and measure how much energy is absorbed or given off. Is this a smart approach? Why or why not? In three to five sentences, explain your reasoning.
arrow_forward
unuunRINO
Consider these reactions, where M represents a generic metal.
2 M(s) + 6HCl(aq) →→2 MC1₂ (aq) + 3 H₂(g)
HCl(g) →→→ HCl(aq)
-
H₂(g) + Cl₂(g) →→→ 2 HCl(g)
MC1₂ (s) → MC1₂ (aq)
Use the given information to determine the enthalpy of the reaction
2 M(s) + 3 Cl₂(g) → 2 MC1₂ (s)
esc
1.
2.
3.
4.
AH =
!
x10
TOOLS
k
2
→
#3
C
4
AH₁ = -651.0 kJ
AH₂ = -74.8 kJ
AH3 = -1845.0 kJ
AH4 = -152.0 kJ
G Search or type URL
do LC
MacBook Pro
%
< (C
6
&
I
7
11
kJ
☆
*
arrow_forward
Consider the potential energy vs reaction coordinate diagram in problem 70 in your text on pg 616. Which of the answers below best describes the change in enthalpy for this reaction?
Group of answer choices
A) thermoneutral
B) endothermic
C) exothermic
D) endogonic
arrow_forward
The reaction between nitrogen monoxide and oxygen is given below:
2 NO(g) + O2(g)
→ 2 NO2(g)
We therefore know that which of the following reactions can also occur?
2 NO2(g) → N2(g) + 2 O2(g)
2 NO(g) → N2(g) + O2(g)
ON2(g) + O2(g)→ 2 NO(g)
None of the Above
arrow_forward
Please don't provide handwritten solution ....
arrow_forward
Use the information below to answer questions 1- 3.
PCI,(g) 2 PCI;(g) + Cl2(8)
PCI,(g) decomposes into PCI,(g) and Cl,(8)
according to the equation above. A pure sample of
PCI,(g) is placed in a rigid, evacuated 1.00 L
container. The initial pressure of the PCI5(g) is
1.00 atm. The temperature is held constant until
the PCI,(g) reaches equilibrium with its
decomposition products. The figures below
show the initial and equilibrium conditions of the
system.
PCI5
Potal = 1.00 atm
PCI5, PCI3, and CI,
Prstal = 1.40 atm
Figure 1: Initial
Figure 2: Equilibrium
As the reaction progresses toward equilibrium, the
rate of the forward reaction
(A) increases until it becomes the same as the
reverse reaction rate at equilibrium
(B) stays constant before and after equilibrium is
reached
(C) decreases to become a constant nonzero rate
at equilibrium
(D) decreases to become zero at equilibrium
If the decomposition reaction were to go to
completion, the total pressure in the container
would be
(A) 1.4…
arrow_forward
3. Lightsticks contain a substance that breaks down during a chemical reaction. A release of energy (as light) accompanies this reaction. Therefore, the amount of light released
is proportional to the number of molecules breaking down.
a) The lightsticks below are in water of different temperatures. Which one is in the warmer water?
b) What would be the effect on the intensity of a lightstick and the duration of its glow if a lightstick was placed in a freezer?
arrow_forward
Suppose a pair of chemical compounds A and B can react in two different ways:
Reaction 1 gives product C.
A+B → C
A+B-D
Reaction 2 gives product D.
The following facts are known about the two reactions:
• Reaction 1 is exothermic and Reaction 2 is endothermic.
• If a reaction vessel is charged ("filled") with A and B, then at first D is produced faster than C.
Use these facts to sketch a qualitative reaction energy diagram for both reactions.
Note: because these sketches are only qualitative, the energies don't have to be exact. They only have to have the right relationship to each other. For example,
if one energy is less than another, that fact should be clear in your sketch.
energy
Reaction 1
reaction coordinate
energy
Reaction 2
reaction coordinate
0
L4
A
#
Ba
arrow_forward
Part 1
A student carried out an investigation to observe the effect of changing
concentration of sulfuric acid on the breakdown of calcium carbonate
(marble) chips. They changed the concentration of the acid between
each test but kept the size of the marble chips constant. The full equation
for the reaction and a graph of the overall results can be seen below.
CaCO3(s) + H₂SO4(aq) → CaSO4(aq) + CO2(g) + H₂O (1)
a)
b)
Rate of Reaction
*
Concentration of Acid (mol dm³)
Explain, using collision theory, why the student obtained
these results, and state what they could conclude about the
effect of changing concentration of acid on the rate of reaction
between calcium carbonate and sulfuric acid.
If the student had ground up the calcium carbonate chips into
a powder and run the tests again, what would you expect to
happen to the rate of reaction? Briefly explain why by
applying collision theory.
Part 2
The student ran the same experiment, but this time changed the
temperature, increasing it…
arrow_forward
The use of living organisms to help clean up areas of pollution is
known as
biodegradation.
O bioremediation.
O bioaccumulation.
O bioreaction.
arrow_forward
→ 2 NH3(g)
Consider the following reaction: N₂(g) + 3 H₂(g)
At time zero there are 0.30 M N₂ and 0.45 M H₂. After 75 seconds have elapsed, the H₂ concentration has fallen to 0.34 M.
How much [N₂] has changed after 75 seconds? Use "E" for scientific notation. Do not enter units as part of your answer.
arrow_forward
SEE MORE QUESTIONS
Recommended textbooks for you

Chemistry & Chemical Reactivity
Chemistry
ISBN:9781337399074
Author:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel
Publisher:Cengage Learning

Chemistry & Chemical Reactivity
Chemistry
ISBN:9781133949640
Author:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel
Publisher:Cengage Learning

Chemistry: Principles and Reactions
Chemistry
ISBN:9781305079373
Author:William L. Masterton, Cecile N. Hurley
Publisher:Cengage Learning
Chemistry: Matter and Change
Chemistry
ISBN:9780078746376
Author:Dinah Zike, Laurel Dingrando, Nicholas Hainen, Cheryl Wistrom
Publisher:Glencoe/McGraw-Hill School Pub Co


World of Chemistry
Chemistry
ISBN:9780618562763
Author:Steven S. Zumdahl
Publisher:Houghton Mifflin College Div
Related Questions
- The previous answer I was given was incorrect. Please be sure of your information. Read the question thoroughly and explain. Thank you.arrow_forwardAnna was asked to identify and explain if the equation CO2 (l) → CO2 (g) was an endothermic or exothermic reaction. However she got it wrong. What is her error and what should the answer have been? Anna's statement: The equation is an exothermic reaction because the energy is released from liquid CO2 to the surroundings to become gaseous CO2 causing the molecules to slow down.arrow_forwardFor the reaction 2N2O5(g) ® 4NO2(g) + O2(g), the following data were collected. t (minutes) [N2O5] (mol/L) 0 1.24 x 10–2 10 0.92 x 10–2 20 0.68 x10–2 30 0.50 x 10–2 40 0.37 x 10–2 50 0.28 ´ 10–2 70 0.15 ´ 10–2 The initial rate of production of NO2 for this reaction is approximately: A) 6.4 x10–4 mol/L • min B) 3.2 x10–4 mol/L • min C) 1.24 x 10–2 mol/L • min D) 1.6 x 10–4 mol/L • min E) none of thesearrow_forward
- 20. Dissolving the salt potassium nitrate in water is an endothermic reaction. What would be observed if potassium nitrate was dissolved in water? a) The water would get very hot. b) The water would get colder. c) The salt would float to the top of the water. d) Bubbles of hydrogen gas would be produced.arrow_forwardPart IV Cabbage Juice Indicator Chop cabbage into small pieces until you have about 2 cups of chopped cabbage. Boil for at least ten minutes to allow time for the color to leach out of the cabbage. Allow it to cool for 15 min • Filter out the plant material to obtain a red-purple-bluish colored liquid. 1. Add 1-2 drops of cabbage juice into a small bowl 2. Add 3-5 drops of vinegar into the bowl with the cabbage juice 3. Observe Is this a chemical change or physical change? Explain? Store the excess cabbage juice in your refrigerator, you will need them for future experiments.arrow_forwardThe U.S. is one of several countries committed to reaching “net-zero” carbon emissions by 2050. This means that by 2050, all carbon dioxide emissions must be matched by the amount of carbon dioxide removed from the air. Why is it essential for all countries in the world to meet carbon reduction commitments like thisarrow_forward
- In experiment #7, you observed the formation of carbon dioxide by reacting baking soda with vinegar. Why was it not possible to relight the candle? A. Carbon dioxide is heavier than air so it stays in the beaker preventing the candle from relighting. B. Carbon dioxide is lighter than air so it escaped from the beaker and the candle should have relit. C. Carbon dioxide is heavier than air so it stays in the beaker and the candle should have relit. D. Carbon dioxide is lighter than air so it escaped from the beaker preventing the candle from relighting.arrow_forwardSuppose a pair of chemical compounds A and B can react in two different ways: A+B → C Reaction 1 gives product C. A+B → D Reaction 2 gives product D. The following facts are known about the two reactions: ● Reaction 1 is endothermic and Reaction 2 is exothermic. • If a reaction vessel is charged ("filled") with A and B, then at first C is produced faster than D. Use these facts to sketch a qualitative reaction energy diagram for both reactions. Note: because these sketches are only qualitative, the energies don't have to be exact. They only have to have the right relationship to each other. For exam if one energy is less than another, that fact should be clear in your sketch. Reaction 1 Reaction 2 energy energy reaction coordinate A + B A + B reaction coordinate Darrow_forwardA scientist wants to perform a reaction in a vacuum chamber to control the experiment as much as possible and to prevent other variables from impacting the reaction. The scientist is trying to determine if the reaction is endothermic or exothermic and measure how much energy is absorbed or given off. Is this a smart approach? Why or why not? In three to five sentences, explain your reasoning.arrow_forward
- unuunRINO Consider these reactions, where M represents a generic metal. 2 M(s) + 6HCl(aq) →→2 MC1₂ (aq) + 3 H₂(g) HCl(g) →→→ HCl(aq) - H₂(g) + Cl₂(g) →→→ 2 HCl(g) MC1₂ (s) → MC1₂ (aq) Use the given information to determine the enthalpy of the reaction 2 M(s) + 3 Cl₂(g) → 2 MC1₂ (s) esc 1. 2. 3. 4. AH = ! x10 TOOLS k 2 → #3 C 4 AH₁ = -651.0 kJ AH₂ = -74.8 kJ AH3 = -1845.0 kJ AH4 = -152.0 kJ G Search or type URL do LC MacBook Pro % < (C 6 & I 7 11 kJ ☆ *arrow_forwardConsider the potential energy vs reaction coordinate diagram in problem 70 in your text on pg 616. Which of the answers below best describes the change in enthalpy for this reaction? Group of answer choices A) thermoneutral B) endothermic C) exothermic D) endogonicarrow_forwardThe reaction between nitrogen monoxide and oxygen is given below: 2 NO(g) + O2(g) → 2 NO2(g) We therefore know that which of the following reactions can also occur? 2 NO2(g) → N2(g) + 2 O2(g) 2 NO(g) → N2(g) + O2(g) ON2(g) + O2(g)→ 2 NO(g) None of the Abovearrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- Chemistry & Chemical ReactivityChemistryISBN:9781337399074Author:John C. Kotz, Paul M. Treichel, John Townsend, David TreichelPublisher:Cengage LearningChemistry & Chemical ReactivityChemistryISBN:9781133949640Author:John C. Kotz, Paul M. Treichel, John Townsend, David TreichelPublisher:Cengage LearningChemistry: Principles and ReactionsChemistryISBN:9781305079373Author:William L. Masterton, Cecile N. HurleyPublisher:Cengage Learning
- Chemistry: Matter and ChangeChemistryISBN:9780078746376Author:Dinah Zike, Laurel Dingrando, Nicholas Hainen, Cheryl WistromPublisher:Glencoe/McGraw-Hill School Pub CoWorld of ChemistryChemistryISBN:9780618562763Author:Steven S. ZumdahlPublisher:Houghton Mifflin College Div

Chemistry & Chemical Reactivity
Chemistry
ISBN:9781337399074
Author:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel
Publisher:Cengage Learning

Chemistry & Chemical Reactivity
Chemistry
ISBN:9781133949640
Author:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel
Publisher:Cengage Learning

Chemistry: Principles and Reactions
Chemistry
ISBN:9781305079373
Author:William L. Masterton, Cecile N. Hurley
Publisher:Cengage Learning
Chemistry: Matter and Change
Chemistry
ISBN:9780078746376
Author:Dinah Zike, Laurel Dingrando, Nicholas Hainen, Cheryl Wistrom
Publisher:Glencoe/McGraw-Hill School Pub Co


World of Chemistry
Chemistry
ISBN:9780618562763
Author:Steven S. Zumdahl
Publisher:Houghton Mifflin College Div