The change in standard free energy for the given reaction is 1 kJ mol at room

# The change in standard free energy for the given

• Notes
• 10

This preview shows page 6 - 9 out of 10 pages.

The change in standard free energy for thegiven reaction is-1 kJ/mol at room tem-perature.What is the equilibrium constantfor the reaction at the same temperature?(R= 8.3 J·K1mol1) 1.0.012.1.0 0196.0 pointsConsider the reaction, The equilibrium constant,K, is 2.If theconcentrations of A, B and C are 2 M, 2 Mand 10 M, respectively, which of the followingwould occur? 020 6.0 points Which of the following gases are more solublein water when their partial pressure above thesolution is increased?
Version 406 – Exam 1 – laude – (51635) 7 2. all of them correct 3. Cl 2 , NO 2 , SO 3 , HI 4. HI , NH 3 5. NO 2 , O 2 , HI 6. NO 2 , SO 3 Explanation: Henry’s Law states that the solubility of gases increase as their partial pressure above the solvent increases. 021 6.0 points What would be the pH of a solution of hypo- bromous acid (HOBr) prepared by dissolving 9.7 grams of the acid in 20 mL of pure wa- ter (H 2 O)? The Ka of hypobromous acid is 2 × 10 9 1. 6 2. 13 3. 4 correct 4. 1 5. 10 Explanation: 9 . 7 g HOBr × 1 mol 97 g = 0 . 1 mol HOBr 0 . 1 mol HOBr 0 . 02 L H 2 O = 5 M HOBr [H + ] = (K a · C a ) 1 / 2 = (2 × 10 9 · 5) 1 / 2 = (10 8 ) 1 / 2 = 10 4 pH = - log[H + ] = - log(10 4 ) = 4 022 6.0 points When making ice cream, salt (NaCl) is added to the water and ice mixture. The equilibrium temperature of this ice-salt water mixture is 1. less than 0 C because salt has a very low specific heat. 2. less than 0 C because the dissolved salt lowers the freezing point of the ice/water mix- ture. correct 3. greater than 0 C because salt melts ice. 4. greater than 0 C because NaCl melts at a higher temperature than water. 5. less than 0 C because salt reacts with water. 6. 0 C because it is at equilibrium. Explanation: The equilibrium temperature of a water- ice mixture is 0 C ( i.e. , the freezing point). When salt is added to the mixture, the freez- ing point ( i.e. , equilibrium temperature) is lowered. Salt does melt ice, but not by rais- ing its temperature, so don’t let that choice confuse you. Salt melts ice by lowering the freezing point. 023 6.0 points Molar Gibbs energy, G m Temperature, T vapor pure liquid solvent Referring to the graph above, and using your knowledge of Δ H solution , complete the following statement concerning boiling point elevation: Adding solute decreases the molar Gibbs energy of the liquid at all temperatures by (increasing/decreasing) the molar (en- thalpy/entropy) of the liquid. This causes
Version 406 – Exam 1 – laude – (51635) 8 Explanation: