CHEM 1311 EXAM 4 Practice Questions With Complete Solutions

When a system _____________, change of E is always negative. correct answer: Gives off heat and does work The reaction 4Al(s) + 3O2(g) --> 2Al2O3(s) Delta H = -3351 kJ is ___________, and therefore heat is ___________ by the reaction. correct answer: Exothermic, released Which of the following is a statement of Hess's law? correct answer: If a reaction is carried out in a series of steps, the H∆ for the reaction will equal the sum of the enthalpy changes for the individual steps. For which of the following reactions is Delta Hrxn equal to the heat of formation for the product? correct answer: (1/2)N2(g) + O2(g) →NO2(g) The value of Delta H for the reaction below is -482 kJ. Calculate the heat (kJ) released to the surroundings when 12.0 g of CO(g) reacts completely. correct answer: 103 In the reaction below, Delta Hf is zero for __________ Ni(s) + 2CO(g) + 2PF3(g) ---> Ni(CO)2(PF3)2 (l) correct answer: Ni(s) The value of Delta H for the reaction below is -126 kJ. ____________ kJ are released when 2.00mol of NAOH is formed in the reaction. 2Na2O2 (s) + 2H2O (l) --> 4NaOH (s) + O2 (g) correct answer: 63 A sample of aluminum metal absorbs 9.86 J of heat, upon which the temperature of the sample increases from 23.2 C to 30.5 C. Since the specific heat capacity of aluminum is 0.90 J/g-K, the mass of the sample is ________g. correct answer: 1.5 Delta H for the reaction IF5 (g) ---> IF3(g) + F2 (g) is __________ kJ, given the data below IF(g) + F2(g) ---> IF3(g) Delta H = -390 kJ IF(g) + 2F2(g) --> IF5(g) Delta H = -745 kJ correct answer: