in the margin indicate full marks for the questions
1. (a) When a spring was 'wound, 100 J
of work was done on it, but 15 J escaped to the surroundings as heat. What was the change in internal energr of the
spring?
(b)
Define standard state of a
1
substance.
(c) Give molecular interpretation of work and heat. 2. (a)
1
2
Entropy is not a convenient criterion for predicting the spontaneity of a process. whv?
(b) State the third law of thermodynamics. 1 ( Turn Ouer ) A15-1700/60
t2l (c)
{3t
Calculate the entropy change of a
(b) Check whether dP is an
system containing a perfect gas when 1'00 mol of the gas doubles its volume at any temperature.
3.
(a)
differential or not.
(c)
For the reaction, N, +3H, -+2NH, the rate is expressed as
_ rdfi zl_1d[NH3l dt3dt2dt
exact
Deduce Kirchhoffs equation to show the variation of enthalpy of a reaction with temperature.
dlNzl
Under what
conditions
5.
(a)
expressions are valid? (b)
What does the rate law indicate?
4.
(b)
What are zeolites? Give one exarnple of a reaction catalyzed by zeolite catalyst.
(a)
:
3x2=6
Calculate the work done when 50 g of iron {molar mass = 55'35 g mol-l) reacts with hydrochloric acid to produce hydrogen gas in an open beaker at 25 "C_
A15-1700/60
( Continued )
Show that for a reversible cyclic process 6ds = o.
Show that the maximum non-expansion work we can obtain from a system at constant pressure and temperature is given by the value of AG for the process.
(c) Answer any ttuo of the foilowing
3x2=6
:
J
The rate law of a homogeneous reaction
A-+P was found to be r=k[A]1'38. (c)
Answer arty tuto of the following
these
Define chemical potential. What is its physical significance? For the following pair of substances, state which substance has the higher chemical potential : HzO[) at 25 "C and 1 atm vs. HzO(g) at 25 oC and I atm
A15-170O/60
(fitrn
Ouer )
{s)
l4l 6.
Answer any ttuo of the following (a)
3x2=6
:
(b)
Express the rate of the foilowing reaction in terms of rate of change of pressure :
(c)
CHsCHo(g) -+ CHo @)+CO(g) (b)
(c)
What is Joule-Thomson effect? Show that Joule-Thomson expansion of a gas is an isoenthalpic process.
(t)
mechanism
8.
Answer any two of the following (a)
0
5x2=
1O
variation of entropy with temperature under various conditions of pressure and volume.
3
the rnolar entropy of a
of neon given that it is mol-l at 2gB K" [Consider Cv,^ for Ne = 12'5 JK-lmol-l I
z,
Starting from the definition of Gibbs' free energr (G), deduce the expressions to show the variation of G with f and P. Based on these expressions, draw necessary graphs to show the variation of G with T and P for solid, liquid and gaseous phases of a substa.nce.
5
at
500 K 146'22 JK-r
+o. -no ,2o" (b)
5x2= 10
:
(a) Why is Cp always greater t}:'an Cy? Show that
cp-cv=[#)"[(#), Ai5-i700/60
:
2
constant-volume sample
:
Answer any tuo of the following
adia-
Obtain the expressions to show the
(iL) Calculate
the basis of following
,o, +o -4 O, +O-&_-+O. 7.
/3) at 1'00 atm
expands reversibly and
o.
o
=5
3
batically to twice its initial volume. Calculate its final pressure.
Applyt.tg steady-state approximation, derive the rate law for the reaction 2Os E) -+ 3O2 (g) on
State the Hess's law. Bxplain the law taking a suitable example.
(iE A sample of Ar(y
The rate of the reaction 2A+B -+2C is doubled when the concentration of B is doubled but increases by a factor of eight when the concentrations of both the reactants are doubled. Find out the rate law of the reaction. What is the overall order of the reaction?
5
.P] ( Continued )
A15-1700/60
(Turn Ouer
)
(6) (c)
t7l
Deduce van't Hoff eqr-rations to show the
(c)
effect of temperature on equilibrium constant of a reaction. Use a van't Hoff
A_>B_>C
equation to predict the effect of temperature on the equilibrium of an
obtain the expressions for the concentrations of the species A, B and C. Draw the plots of [A], [B]and [C]against time.
exothermic reaction and an endothermic reaction.
9.
Answer any two of the following
(a)
For the consecutive reactions
***
5x2=1O'
:
For the second-order reaction aA -+products
(t) integrate the rate
law;
(iL) on the basis of this integrated rate
law, d.raw a plot ^ ol J4J- against
[A]o '
f;
(iii) d.erive an expression for the halflife of the reaction in terms of k and 2+I+2
lAlo.
(b) Give the Rice-Herzfeld
mechanism for the following thermal decomposition of ethanal in absence of air :
cH3CHo{s) -+ CHo @) + Co(s) Based on this rnechanism, derive a rate law for the reaction.
415-17OO/60
( Continued
)
415-170O/60
3 (Sem-l) CHM M
1
bsc-chemistry-m-sem-1-paper-1.1-2014.pdf
What is Joule-Thomson effect? Show. that Joule-Thomson expansion of a gas. is an isoenthalpic process. 5. (t) State the Hess's law. Bxplain the. law taking a ...
