Which of the following statements is FALSE about energy changes? (a) When a process releases energy the potential energy increases. (b) Wood buring is an exothermic process. (c) Reactions that move toward a lower energy/ more stable state are usually spontaneous. (d)A change that absorbs energy is an endothermic process.

Would the amount of heat absorbed by the dissolution in Example 5.6 appear greater, lesser, or remain the same if the heat capacity of the calorimeter were taken into account? Explain your answer.

9.20 State the first law of thermodynamics briefly in your own words.

9.47 If 14.8 kJ of heat is given off when 1.6 g of HCl condenses from vapor to liquid, what is Hcond for this substance?

Define the standard enthalpy of formation. What are standard states for elements and for compounds? Using Hess's law, illustrate why the formula Hreaction=npHf(products)nfHf(reactants) works to calculate H for a reaction.

The combustion of methane can be represented as follows: a. Use the information given above to determine the value of H for the combustion of methane to form CO2(g) and 2H2O(l). b. What is Hf for an element in its standard state? Why is this? Use the figure above to support your answer. c. How does H for the reaction CO2(g) + 2H2O (1) CH4(g) + O2(g) compare to that of the combustion of methane? Why is this?

Given 2Al2O3(s)4Al(s)+3O2(g)H=3351.4kJ (a) What is the heat of formation of aluminum oxide? (b) What is H for the formation of 12.50 g of aluminum oxide?

9.23 Which system does not work: (a) E=436J , q=400J ; or E=317J , q=347J ?

The overall reaction that occurs when sugar is metabolized is C12H22O11(s)+12O2(g)12CO2(g)+11H2O(l) For this reaction, H° is -5650 kJ and G° is -5790 kJ at 25°C. (a) If 25% of the free energy change is actually converted to useful work, how many kilojoules of work are obtained when one gram of sugar is metabolized at body temperature, 37°C? (b) How many grams of sugar would a 120-lb woman have to eat to get the energy to climb the Jungfrau in the Alps, which is 4158 m high? ( w=9.79103mh, where w= work in kilojoules, m is body mass in kilograms, and h is height in meters.)

9.42 Why is enthalpy generally more useful than internal energy in the thermodynamics of real world systems?