Suppose a pair of chemical compounds A and B can react in two different ways: A+B C Reaction 1 gives product C. A+B D →> Reaction 2 gives product D. The following facts are known about the two reactions: • Reaction 1 is endothermic and Reaction 2 is exothermic. • If a reaction vessel is charged ("filled") with A and B, then at first C is produced faster than D. Use these facts to sketch a qualitative reaction energy diagram for both reactions. Note: because these sketches are only qualitative, the energies don't have to be exact. They only have to have the right relationship to each other. For if one energy is less than another, that fact should be clear in your sketch. energy A + B Reaction 1 reaction coordinate energy A + B Reaction 2 reaction coordinate ☑

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.

xplain why aluminum cans make good storage containers for soft drinks. Styrofoam cups can be used to keep coffee hot and cola cold. How can this be?

One of the components of polluted air is NO. It is formed in the high-temperature environment of internal combustion engines by the following reaction: N2(g)+O2(g)2NO(g)H=180KJ Why are high temperatures needed to convert N2 and O2 to NO?