A₂+B₂-2 AB Suppose the reaction is carried out at two temperatures for the same amount of time as shown below. Which picture represents the result at the higher temperature? The reaction proceeds for the same amount of time at both temperatures. Select the single best answer. A O B₂ AB BO X S

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.

Monochloroethane (C2H5Cl) can be produced by the direct reaction of ethane gas (C2H6) with chlorine gas or by the reaction of ethylene gas (C2H4) with hydrogen chloride gas. The second reaction gives almost a 100% yield of pure C2H5Cl at a rapid rate without catalysis. The first method requires light as an energy source or the reaction would not occur. Yet G for the first reaction is considerably more negative than G for the second reaction. Explain how this can be so.

Calculate H for the reaction N2H4(l) + O2(g) N2(g) + 2H2O(l) given the following data: 2NH3(g)+3N2O(g)4N2(g)+3H2O(l)H=1010.kJN2O(g)+3H2(g)N2H4(l)+H2O(l)H=317kJ2NH3(g)+12O2(g)N2H4(l)+H2O(l)H=143kJH2(g)+12O2(g)H2O(l)H=286kJ