Consider the combustion of methane (as represented by the following equation). This is the reaction that occurs for a Bunsen burner, which is a source of heat for chemical reactions in the laboratory. CH 4(9) +20 2(g) =CO2(g) + 2H 20(g) For the system at chemical equilibrium, which of the following explains what happens if the temperature is reduced? O a. The equilibrium position is shifted to the left and the value for K increases. O b. The equilibrium position is shifted to the right and the value for K increases. O c. The equilibrium position is shifted to the right and the value for K decreases. Od. The equilibrium position is shifted but the value for K stays constant. Oe. The equilibrium position is shifted to the left and the value for K decreases.

Indicate which of the following processes are reversible. (a) Nitrogen gas expands into a vacuum. (b) Dry ice, CO2(s), sublimes at 25 C and 1.0 atm. (c) Energy as heat is added to a mixture of ice and water at 0 C, causing some of the ice to melt. (d) Methanol and ethanol mix forming a homogeneous solution.

9.96 Most first aid "cold packs" are based on the endothermic dissolution of ammonium nitrate in water: NH4NO3(s)NH4+(aq)+NO3(aq) H= 25.69 kJ A particular cold pack contains 50.0 g of NH4NO3 and 125.0 g of water. When the pack is squeezed, the NH4NO3dissolves in the water. If the pack and its contents are initially at 24.0°C, what is the lowest temperature that this bag could reach? (Assume that the ammonium nitrate solution has a specific heat of 4.25J g-l K-l, and that the heat capacity of the bag itself is small enough to be neglected.)

1. A process is spontaneous in the direction that moves it away from equilibrium toward equilibrium

Should heat be added as a reactant or as a product to each of the following equations for chemical reactions based on the given thermicity for the reaction? a. H2 + Cl2 2HCl (exothermic) b. 4NO + 6H2O 4NH3 + 5O2 (endothermic) c. 2H2O + 2Cl2 4HCl + O2 (endothermic) d. 2H2O 2H2 + O2 (exothermic)

Consider the equilibrium process depicted in Fig. 17.6. When does the equilibrium state occur?

The following equilibrium is established in a closed container: C(s)+O2(g)CO2(g)H=393kJmol1 How does the equilibrium shift in response to each of the following stresses? (a) The quantity of solid carbon is increased. (b) A small quantity of water is added, and CO2 dissolves in it. (c) The system is cooled. (d) The volume of the container is increased.

Write a chemical equation for each process and classify each as reactant-favored or product-favored. (a) A puddle of water evaporates on a summer day. (b) Silicon dioxide (sand) decomposes to the elements Silicon and oxygen. (c) Paper, which is mainly cellulose (C6H10O5)n, bums at a temperature of 451 F. (d) A pinch of sugar dissolves in water at room temperature.

. Consider the following exothermic reaction at equilibrium: N2(g)+3H2(g)2NH3(g)Predict how the following changes affect the number of moles of each component of the system after equilibrium is re-established by completing the table. Complete the table with the terms increase, decrease, or no change. N2 H2 NH3 Add N2(g) Remove H2(g) Add NH3(g) Add Ne(g) (constant V) Increase the temperature Decrease the volume (constant T) Add a catalyst

. Consider the reaction 2CO(g)+O2(g)2CO2(g)Suppose the system is already at equilibrium, and then an additional mole of CO2(g) is injected into the system at constant temperature. Does the amount of O2(g) in the system increase or decrease? Does the value of K for the reaction change?