Consider the reaction below. Upper Z n (s) plus upper C u superscript 2 plus (a q) right arrow upper Z n superscript 2 plus (a q) plus upper C u (s).

Which half reaction correctly describes the oxidation that is taking place?
Z n (s) right arrow upper Z n superscript 2 plus (a q) plus e superscript minus.
Upper Z n (s) right arrow upper Z n superscript 2 plus (a q) plus 2 e superscript minus.
Upper C u superscript 2 plus (a q) plus 2 e superscript minus right arrow upper C u (s).
Upper C u superscript 2 plus (a q) plus e superscript minus right arrow upper C u (s).

1. baking powder is a 1: 1 molar mixture of cream of tartar (khc4h4o6) and baking soda (nahco3). a recipe calls for two teaspoons (a total of 8.0 grams) of cream of tartar. how much baking soda must be added for both materials to react completely?

Two nitro no2 groups are chemically bonded to a patch of surface. they can't move to another location on the surface, but they can rotate (see sketch at right). it turns out that the amount of rotational kinetic energy each no2 group can have is required to be a multiple of ε, where =ε×1.010−24 j. in other words, each no2 group could have ε of rotational kinetic energy, or 2ε, or 3ε, and so forth — but it cannot have just any old amount of rotational kinetic energy. suppose the total rotational kinetic energy in this system is initially known to be 32ε. then, some heat is removed from the system, and the total rotational kinetic energy falls to 18ε. calculate the change in entropy. round your answer to 3 significant digits, and be sure it has the correct unit symbol.

1. list three scientific reasons cockroaches may fly.