When does a single-displacement reaction occur? A. When a substance, usually containing carbon, reacts with oxygen
to produce energy in the form of heat and light
B. When one element replaces another element in a compound
during a chemical reaction
C. When a substance is broken down into two or more simpler
substances in a chemical reaction
D. When a single element forms two double elements

7. what temperature is need to just dissolve 50 g of nh4cl in 75 g of water? '

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.

How does concentration affect reaction rate