pl answer Q 20
pl answer Q 20 CHEMICAL TH RMODYNAMI Column •I A) Adiabatic expansion of a gas C) AG=AH+T D) —R for monoatomic ideal gas OBJECTIVE CHEMISTRY-XIB Column-II Q) Isoentropie S) TV 7-1 = constant 24. 25. 11 Section - D 16. The enthalpy change involved in the oxidation Of glucoses —3000KJ/moI 25% Of this energy is available for muscular work If 100 KJ muscular work is needed to walk I kilometre, the maximum distance that a person Will be able to walk after eating 144 gm Of glucose is 17. The enthalpy of hydration Of Na• and Cl- ions are in the ratio a : b. The lattice energy of NaCl solid is 772 KJ/mol, enthalpy of its solution is 2KJ/mo/. The enthalpy of hydration of Ct- ion is 350 KJ/mo/. If b is 5/2, what is a ? 18. Look at the following diagram 80 40 PROGRESS OF REACTION The enthalpy change for the reaction A will be —x2kJ ,The value of x is 19. Heat of neutralisation of a polybasic acid by strong base is —54.8 kcal mol-l. What is basicity of the acid 20. Calculate the standard internal change in multiples of —102 KJ for the reaction OF2(g) + H20(g) 2HF at 298K. The standard enthalpies of formation of OF2( , H20(g), HF(g) are +20, +250 and — 270 KJ mole-I 21. For a liquid, enthalpy of fusion is 1.435 kcal mol-l and molar entropy change is 5.26 cal mol-1K-1. The freezing point of liquid in celcius will be 22. The value of logK for the reaction A is I Ox. (A HO --54.07KJmorl ; R = 8.314 JK-I mol-l ; A so = 10JK-1mo/-1 ) calculate the value of 'x' r298K 23. In how many of the following entropy increases ? a) +2NH3( ) c) -+H20(9 b) PC15cg) +C12(gj e) 2NaHC036) f) NH2C02NH4 2(g) g) H20(l) -H206) 132 APEX SERIES for Sri Chaitany

a) T h e e n t h a l p y o f f o r m a t i o n i s d e f i n e d a s t h e e n t h a l p y c h a n g e d u r i n g t h e f o r m a t i o n o f 1 m o l e o f a c o m p o u n d a t s \tan d a r d c o n d i t i o n . S i n c e t h e r e a c t i o n i s n o t m e a s u r e d a t 298 K (25^{0} C) i t d o e s n o t r e p r e s e n t t h e e n t h a l p y o f f o r m a t i o n b) R e f e r t h e a b o v e s t a t e m e n t, t h e r e a c t i o n b r e p r e s e n t s t h e f o r m a t i o n o f e n t h a l p y f o r 2 m o l e s o f H B r . S o i t d o e s n o t r e p r e s e n t t h e e n t h a l p y o f f o r m a t i o n . I I) O F_{2} + H_{2} O \to O_{2} + 2 H F ∆ H = H_{p} - H_{r} = [2 H_{H F} + H_{O_{2}}] - [H_{O F_{2}} + H_{H_{2} O}] = [2 \times - 268.6 + 0] - [23 + - 241.8] = - 537.2 + 218.8 = - 318.4 k J T h e r e l a t i o n b e t w e e n e n t h a l p y a n d e n t r o p y i s ∆ H = ∆ U + R T ∆ n ∆ n = n_{p} - n_{r} = 3 - 2 = 1 ∆ U = ∆ H - R T ∆ n = - 318.4 - [8.314 \times 10^{- 3} \times 300 \times 1] = - 320.9 k J