Given the following data Ca ( s ) + 2 C ( g r a p h i t e ) → CaC 2 ( s ) Δ H = − 62.8 KJ Ca ( s ) + 1 2 O 2 ( g ) → CaO ( s ) Δ H = − 635.5 KJ CaO ( s ) + H 2 O ( l ) → Ca ( OH ) 2 ( a q ) Δ H = − 653.1 KJ C 2 H 2 ( g ) + 5 2 O 2 ( g ) → 2 CO 2 ( g ) + H 2 O ( l ) Δ H = − 1300. KJ C ( g r a p h i t e ) + O 2 ( g ) → CO 2 ( g ) Δ H = − 393.5 KJ Calculate ∆ H for the reaction CaC 2 ( s ) + 2 H 2 O ( l ) → Ca ( OH ) 2 ( a q ) + C 2 H 2 ( g )
Given the following data Ca ( s ) + 2 C ( g r a p h i t e ) → CaC 2 ( s ) Δ H = − 62.8 KJ Ca ( s ) + 1 2 O 2 ( g ) → CaO ( s ) Δ H = − 635.5 KJ CaO ( s ) + H 2 O ( l ) → Ca ( OH ) 2 ( a q ) Δ H = − 653.1 KJ C 2 H 2 ( g ) + 5 2 O 2 ( g ) → 2 CO 2 ( g ) + H 2 O ( l ) Δ H = − 1300. KJ C ( g r a p h i t e ) + O 2 ( g ) → CO 2 ( g ) Δ H = − 393.5 KJ Calculate ∆ H for the reaction CaC 2 ( s ) + 2 H 2 O ( l ) → Ca ( OH ) 2 ( a q ) + C 2 H 2 ( g )
Solution Summary: The author defines enthalpy change as amount of heat absorbed or released in chemical reactions at constant pressure.
Ca
(
s
)
+
2
C
(
g
r
a
p
h
i
t
e
)
→
CaC
2
(
s
)
Δ
H
=
−
62.8
KJ
Ca
(
s
)
+
1
2
O
2
(
g
)
→
CaO
(
s
)
Δ
H
=
−
635.5
KJ
CaO
(
s
)
+
H
2
O
(
l
)
→
Ca
(
OH
)
2
(
a
q
)
Δ
H
=
−
653.1
KJ
C
2
H
2
(
g
)
+
5
2
O
2
(
g
)
→
2
CO
2
(
g
)
+
H
2
O
(
l
)
Δ
H
=
−
1300.
KJ
C
(
g
r
a
p
h
i
t
e
)
+
O
2
(
g
)
→
CO
2
(
g
)
Δ
H
=
−
393.5
KJ
Calculate ∆H for the reaction
CaC
2
(
s
)
+
2
H
2
O
(
l
)
→
Ca
(
OH
)
2
(
a
q
)
+
C
2
H
2
(
g
)
A cylinder contains 12 L of water vapour at 150˚C and 5 atm. The temperature of the water vapour is raised to 175˚C, and the volume of the cylinder is reduced to 8.5 L. What is the final pressure of the gas in atmospheres?
assume that the gas is ideal
On the next page is an LC separation of the parabens found in baby wash. Parabens are
suspected in a link to breast cancer therefore an accurate way to quantitate them is desired.
a. In the chromatogram, estimate k' for ethyl paraben. Clearly indicate what values you used for
all the terms in your calculation.
b. Is this a "good" value for a capacity factor? Explain.
c. What is the resolution between n-Propyl paraben and n-Butyl paraben? Again, indicate clearly
what values you used in your calculation.
MAU
| Methyl paraben
40
20
0
-2
Ethyl paraben n-Propyl paraben
n-Butyl paraben
App ID 22925
6
8
min
d. In Figure 4, each stationary phase shows some negative correlation between plate count
and retention factor. In other words, as k' increases, N decreases. Explain this relationship
between k' and N.
Plate Count (N)
4000
3500
2500
2000
1500
1000
Figure 4. Column efficiency (N) vs retention factor (k') for 22
nonionizable solutes on FMS (red), PGC (black), and COZ (green). 3000
Eluent compositions (acetonitrile/water, A/W) were adjusted to obtain
k' less than 15, which was achieved for most solutes as follows: FMS
(30/70 A/W), PGC (60/40), COZ (80/20). Slightly different
compositions were used for the most highly retained solutes. All
columns were 50 mm × 4.6 mm id and packed with 5 um particles,
except for COZ, which was packed with 3 um particles. All other
chromatographic conditions were constant: column length 5 cm,
column j.§. 4.6 mm, flow rate 2 mL/min, column temperature 40 °C,
and injection volume 0.5 μL
Log(k'x/K'ethylbenzene)
FMS
1.5
1.0
0.5
0.0
ཐྭ ཋ ཤྩ བྷྲ ;
500
0
5
10…
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