475

13 4. Specify the sign of the change in entropy in the following reactionswithout making a calculation: C 15 H 31 COOH (s) + 23O 2 (g) = 16CO 2 (g)+ 16H 2 O (g) 2CH 3 OH (g) + 3O 2 (g) = 4H 2 O (g) + 2CO 2 (g) 5. Calculate the ∆S of reaction ATP + H 2 O = ADP + P at 37  0 C. (∆G and ∆H of the reaction are –30.9 and 20.1 kJ/mol, respectively). Answer : 0.16 kJ/mol. 6. Calculate the values of ∆G of the following iron (II) oxide reduction reactions: a) FeO (s) + CO = Fe (s) + CO 2 (g); ∆G  0 (FeO) = –244 kJ/mol; ∆G  0 (CO) = –137 kJ/mol; b) FeO (s) + C (graphite) = Fe (s) + CO 2 (g) ∆ G  0 (CO 2 ) = –394.4 kJ/mol. What of these reactionsare most likely to occur? 7. What is the value of ∆G, if the equilibrium constant at 298 K eq = 1. What is the value of the equilibrium constant at 298 K eq , if ∆G = 0? 8. The condition that causes the equilibrium to shift in the direction of the reverse reaction (to the left): CO 2 + C (t) ⇔ 2CO – Q: 1) increasing in carbon concentration; 2) cooling; 3) increasing the concen- tration of carbon monoxide (IV); 4) pressure reduction 9. The equilibrium constant of the reaction of thermal denaturation of chy- motrypsinogen at pH 2 and 50 °C is 32.7. Calculate the value of the standard enthalpy of the process if it is known that ∆So = + 1.32 kJ/(mol K). Answer: 417 kJ/mol. Laboratory work Experiment 1. Displacement of chemical equilibrium with a change in the concentration of reagents. The reaction for the formation of iron (III) thiocyanate is used for the experiment: FeCl 3 + 3KNCS = Fe (NCS) 3 + 3KCl Iron (III) thiocyanate is intensively colored red, the solution of FeCl 3  – in yellowish. KNCS and KCl solutions are colorless. Pour 20 ml of water in a small measuring beaker, add 1 drop of saturated so- lutions of FeCl3 and KNCS. Stir the solution with a glass rod. The resulting so- lution is poured into four tubes. Then add 1 drop of concentrated FeCl3 solution to the first tube. What are you watching? Record the observed color change in