O 2. S + HN ons emsido (a catalyst like pipridine) O HO 1100 O heat bemujer ad 05 10

Consider the following statements: In general, the rate of a chemical reaction increases a bit at first because it takes a while for the reaction to get warmed up. After that, however, the rate of the reaction decreases because its rate is dependent on the concentrations of the reactants, and these are decreasing. Indicate everything that is correct in these statements, and indicate everything that is incorrect. Correct the incorrect statements and explain.

Silicon forms a series of compounds analogous to the al-kanes and having the general formula SinH2n+2. The first of these compounds is silane, SiH4, which is used in the electronics industry to produce thin ultrapure silicon films. SiH4(g) is somewhat difficult to work with because it is py-ropboric at room temperature—meaning that it bursts into flame spontaneously when exposed to air. (a) Write an equation for the combustion of SiH4(g). (The reaction is analogous to hydrocarbon combustion, and SiO2 is a solid under standard conditions. Assume the water produced will be a gas.) (b) Use the data from Appendix E to calculate ? for this reaction. (c) Calculate G and show that the reaction is spontaneous at 25°C. (d) Compare G for this reaction to the combustion of methane. (See the previous problem.) Are the reactions in these two exercises enthalpy or entropy driven? Explain.

The following equation represents a reversible decomposition: CaCO3(s)CaO(s)+CO2(g) Under what conditions will decomposition in a closed container proceed to completion so that no CaCO3 remains?

7-43 (Chemical Connections 7A and 7B) Why is a high fever dangerous? Why is a low body temperature dangerous?

Define these terms: (a) unimolecular reaction (b) bimolecular reaction (c) elementary reaction (d) overall reaction

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?

. Hydrogen gas and chlorine gas in the presence of light react explosively to form hydrogen chloride H2(g)+Cl2(g)2HCl(g)The reaction is strongly exothermic. Would an increase in temperature for the system lend to favor or disfavor the production of hydrogen chloride?

. Suppose a reaction has the equilibrium constant K=1.7108at a particular temperature. Will there be a large or small amount of unreacted starting material present when this reaction reaches equilibrium? Is this reaction likely to be a good source of products at this temperature?

By which of the following mechanisms does a catalyst operate? a. It decreases the activation energy barrier for a reaction. b. It serves as a reactant and is consumed. c. It increases the temperature of a reaction. d. It increases the concentration of reactants.