Thermodynamics and Chemistry

CHAPTER 11 REACTIONS AND OTHER CHEMICAL PROCESSES

PROBLEMS 360

Table 11.1 Data for Problem 11. 5 a

Substance ÅfH/kJ mol^1 M/g mol^1

H 2 O(l) 285:830 18:0153

Na 2 S 2 O 3 
5H 2 O.s/ 2607:93 248:1828

Na 2 S 2 O 3 in 50 H 2 O 1135:914

Na 2 S 2 O 3 in 100 H 2 O 1133:822

Na 2 S 2 O 3 in 200 H 2 O 1132:236

Na 2 S 2 O 3 in 300 H 2 O 1131:780

aRef. [ 165 ], pages 2-307 and 2-308.

11.5 Table11.1lists data for water, crystalline sodium thiosulfate pentahydrate, and several sodium
thiosulfate solutions. FindÅHto the nearest0:01kJ for the dissolution of5:00g of crystalline
Na 2 S 2 O 3
5H 2 O in50:0g of water at298:15K and 1 bar.

Table 11.2 Data for Problem 11. 6. Molar in-

tegral enthalpies of dilution of aqueous HCl

(m^0 BD3:337mol kg^1 ) at 25 C.a

m^00 B=mol kg^1 ÅHm.dil,m^0 B!m^00 B/=kJ mol^1

0:295 2:883

0:225 2:999

0:199 3:041

0:147 3:143

0:113 3:217

0:0716 3:325

0:0544 3:381

0:0497 3:412

0:0368 3:466

0:0179 3:574

0:0128 3:621

aRef. [ 155 ].

11.6 Use the experimental data in Table11.2to evaluateLAandLBat 25 C for an aqueous HCl
solution of molalitymBD0:0900mol kg^1.