Order Chemical Energetics and Thermodynamics Assignment

Order Chemical Energetics and Thermodynamics Assignment
1. Calculate the work done in calories in the isothermal expansion of a system by one litre at the constant pressure of
740 mm T = 298 K.
2. ‘Hf
values for C2
H2(g) and C2
H6(g) are 47.0 k cal mol1
and 29.3 k cal mol1
respectively. Calculate for the reaction
C2
H2(g) 2H2(g)oC2
H6(g) both ‘H and ‘U; T = 298 K.
3. 28 g of oxygen at 0qC and 5 atm pressure expand adiabatically so that the final pressure is one atm. Calculate the final
temperature (J for oxygen = 1.4).
4. 5 litres of oxygen at 2 atm expand adiabatically to 20 litres. Calculate the work done in litre atm J = p
v
C
C
= 1.4 for
oxygen.
5. The enthalpy of combustion of ethylene, C2
H4(g) is 333.00 k cal mol1
Enthalpies of formation of CO2(g) and H2
O() are 97.3 and 68.4 k cal mol1
respectively. T = 298 K. Calculate ‘Hf
of C2
H4(g).
6. The enthalpy of neutralization of a weak monoprotic acid is 13.385 k cal eqt1
. Assuming that the acid is 14% ionized
in solution, Calculate the enthalpy of ionization of the acid. ‘H for the reaction H3
O OH
o2H2
O in solution
is 13.7 k cal eqt1
Order Chemical Energetics and Thermodynamics Assignment
7. The enthalpies of neutralization of two weak monoprotic acids, HA and HB are 13350 cal eqt1
and 11200 cal eqt1
respectively. When one equivalent of NaOH in dilute solution is added to a mixture of 1 equivalent of HA and 1 equivalent
of HB, 12900 calories are evolved. Find the number of moles of HA and HB that remain as unreacted in the mixture.
8. Calculate ‘Hf
for CO(g) given ‘Uf
= 29.60 k cal mol1
given ‘Hf
for CO2(g) = 97.30 k cal. Calculate ‘U for the reaction CO(g) 2(g)
1
O
2
oCO2(g). T = 298K.
9. Calculate ‘H : C2
H2(g) H2
O(l)oCH3 CHO(l) given
(i) 2C(s) H2(g)oC2
H2(g) ‘Hf
= 46.8 k cal mol1
(ii) H2(g) 2(g)
1
O
2
oH2
O()
‘H = 68.4 k cal mol1
(iii) C(s) O2(g)oCO2(g); ‘H = 97.3 k cal mol1
(iv) CH3
CHO(l)
5
2
O2(g)o2CO2(g) 2H2
O(l); ‘H = 282.0 k cal mol1
10. The enthalpies of neutralization of the two acids HA and HB are 13.350 and 13.7 k cal respectively. Calculate the
enthalpy change of the reaction NaA HB HA NaB.
Straight Objective Type Questions
Directions: This section contains multiple choice questions. Each question has 4 choices (a), (b), (c) and (d), out of
which ONLY ONE is correct.
11. 5 g of zinc(Atomic weight ҩ 65 assumed) react with excess of dilute acid at 15qC at the atmospheric pressure = 750
mm. Calculate in calories the work done against the atmosphere by the evolving hydrogen gas.
(a) 22.3 (b) 32.3 (c) 44.0 (d) 34.4
Chemical Energetics and Thermodynamics 5.35