B C A Reaction Pathway Part 1: Does the diagram illustrate an endothermic or an exothermic reaction? Give reasons in support of your answer. Part 2: Describe how you can determine the total change in enthalpy and activation energy from the diagram and if each is positive or negative. Potential Energy

Substances that poison a catalyst pose a major concern for many engineering designs, including those for catalytic converters. One design option is to add materials that react with potential poisons before they reach the catalyst. Among the commonly encountered catalyst poisons are silicon and phosphorus, which typically form phosphate or silicate ions in the oxidizing environment of an engine. Group 2 elements are added to the catalyst to react with these contaminants before they reach the working portion of the catalytic converter. If estimates show that a catalytic converter will be exposed to 625 g of silicon during its lifetime, what mass of beryllium would need to be included in the design?

When writing an equation, how is a reversible reaction distinguished from a nonreversible reaction?

The reaction of carbon monoxide with hydrogen to form methanol is quite slow at room temperature. As a general rule, reactions go faster at higher temperatures. Suppose that you tried to speed up this reaction by increasing the temperature. (a) Assuming that rH does not change very much as the temperature changes, what effect would increasing the temperature have on rSsurroundings? (b) Assuming that rS for a reaction System does not change much as the temperature changes, what effect would increasing the temperature have on rSuniverse?

When a mixture of hydrogen and bromine is maintained at normal atmospheric pressure and heated above 200. °C in a closed container, the hydrogen and bromine react to form hydrogen bromide and a gas-phase equilibrium is established. Write a balanced chemical equation for the equilibrium reaction. Use bond enthalpies from Table 6.2 ( Sec. 6-6b) to estimate the enthalpy change for the reaction. Based on your answers to parts (a) and (b), which is more important in determining the position of this equilibrium, the entropy effect or the energy effect? In which direction will the equilibrium shift as the temperature increases above 200. °C? Explain. Suppose that the pressure were increased to triple its initial value. In which direction would the equilibrium shift? Why is the equilibrium not established at room temperature?

Define the terms product-favored System and reactant-favored System. Give one example of each.

Which sentence best describes the following reaction? 2H2(g)+O2(g)2H2O(l)+heat a. It is an endothermic reaction. b. It is an exothermic double-replacement reaction. c. It is a synthesis reaction that is also exothermic. d. It is a decomposition reaction that is also endothermic.

Old-fashioned smelling salts consist of ammonium carbonate, (NH4)2CO3. The reaction for the decomposition of ammonium carbonate (NH4)2CO3(s)2NH3(g)+CO(g)+H2O(g) is endothermic. Would the smell of ammonia increase or decrease as the temperature is increased?

Classify each of the reactions according to one of the four reaction types summarized in Table 18.1. (a) Fe2O3(s) + 2 Al(s) 2 Fe(s) + Al2O3(s) rH = 851.5 kj/mol-rxn rS = 375.2 J/K mol-rxn (b) N2(g) + 2 O2(g) 2 NO2(g) rH = 66.2 kJ/mol-rxn rS = 121.6 J/K mol-rxn TABLE 18.1 Predicting Whether a Reaction Will Be Spontaneous Under Standard Conditions

The internal energy of a system is said to be the sum of the kinetic and potential energies of all the particles in the system. Section 10. 1 discusses potential energy and kinetic energy in terms of a ball on a hill. Explain potential energy and kinetic energy for a chemical reaction.