chemistry calculations
celcla
assingment.docCHM/150
Week 4 Hess’ Law
Name: _____________________________________________________
Instructions: Highlight the entire most correct answer for each problem or answer the questions or fill in the blanks – must show work for full credit in calculation problems.
Review the following Youtube video: https://www.youtube.com/watch?v=_NLAgSnqNOE
1. Calculate the standard enthalpy change, ΔHo, for the formation of 1 mol of strontium carbonate (the material that gives the red color in fireworks) from its elements.
kJ
394
-
H
(g)
CO
(g)
O
)
C(graphite
(3)
kJ
234
-
H
(s)
SrCO
(g)
CO
(s)
SrO
(2)
kJ
592
-
H
(s)
SrO
(g)
O
(s)
Sr
(1)
is
available
n
informatio
The
(s)
SrCO
(g)
O
)
C(graphite
(s)
Sr
2
2
3
2
2
2
1
3
2
2
3
=
°
D
®
+
=
°
D
®
+
=
°
D
®
+
®
+
+
2. The combination of coke and steam produces a mixture called coal gas, which can be used as a fuel or as a starting material for other reactions. If we assume coke can be represented by graphite, the equation for the production of coal gas is
kJ
206.1
H
(g)
CO
(g)
H
3
(g)
O
H
(g)
CH
(3)
kJ
41.2
-
H
(g)
H
(g)
CO
(g)
O
H
(g)
CO
(2)
kJ
131.3
H
(g)
H
(g)
CO
(g)
O
H
C(s)
(1)
:
reaction
of
enthalpies
standard
following
the
from
reaction
for this
change
enthalpy
standard
the
Determine
(g)
CO
(g)
CH
(g)
O
H
2
(s)
C
2
2
2
4
2
2
2
2
2
2
4
2
=
°
D
+
®
+
=
°
D
+
®
+
=
°
D
+
®
+
+
®
+
3. The enthalpy change due to a temperature change is a change in
A. kinetic energy.
B. potential energy.
4. An enthalpy change at constant temperature and pressure is designated by the symbol
A. q
B. H
C. _H
D. c
5. The molar enthalpy change for a process is designated by the symbol
A. q
B. H
C. H
D. c
6. Another word for melting is _______________.
7. Another word for boiling is _______________.
8. Calculate the enthalpy change when a 10.0 g of water is heated from 10.0°C to 25.0°C.
Show working.
9. Calculate the enthalpy change when 10.0 g of water at 100°C is converted to 10.0 g of
Vapor at 100°C. Show work.
10. Calculate the total change in enthalpy when 100 g of ice at -5.00°C is converted to water at 85.00°C. Show work.
