Question

5. (20 pts) Consider the following reaction OF:(g)+ H20(g) (a) Using this information along with data in the appendix of your textbook, calculate AH(OF, (g)) in kJ/mole at 25 C. (b) If 15.0 g of OF (g) and 10.0 g of H2Og) react, how much heat, expressed in kJ is released? Hint: First calculate the limiting reagent. 2 HF(g) + O(g) AH (kJ/mole)--318 kJ/mole Consider two Styrofoam coffee cups. If cup # 1 contains 102.0 mL of water at 81.8 "C and cup # 2 contains 74.6 ml. of water at 13.5 °C, what is the final temperature, in "C, when the contents of cup #1 are poured into cup # 2? 1gnore the heat capacity of the cup. Assume that the density of water is 1.00 g/ml. 6.(20 pts)

Answer 1

Given reaction ý ofa cg) + Hockey — a ufcges + O2(g): 04.-318 Dholen - E DHO (products} - { DHg (recetents) ca Dug CHF) + AH (9) - Off (ofs-Ahq Cathely -318 : 21-221.1) + 0- 149 (0f2) = (-241.8) - The standand heat of bormation of ofz, 047 = 17.6 Ksimore from the balanced equation, 2 54 grams of of reacts with 18 gms of the - 15gm of of 2 (9) deacts with 15x18 = 5gme of the 54 A of 2 (9) ý limiting reagent Number of moles of of = 0.28 molen lot = mawt 15: su she amant of heat evolved for the reaction of imale of off with wated į 318ks ghe amant of heat evolved for the reaction of 0.28 mole of of will water is 88.34 kJ

Heat gained by cold water Heat lost lal hot wated = MS AT) hot wateda mSAT) cold water 102 x 4.184x681.8-t)= 74.6 x4.184x(t-13:5) 3 102x (81.8-t) = 74.6 x 14-13.5) t= 52.948€ ghe tinal temperature is 52.95€ specific heat of wateda 9.184 Ile-mule of H₂O= mass of tho because d=1gmine can this case, and volume