In lab, a student was given a hydrated version of NiCl2 as the unknown. The initial mass of the hydrated salt was 0.821 g. The student heated the crucible for 10 minutes with the cover slightly ajar. After cooling, the dried salt weighed 0.448 g. Based on these results, answer the following questions. a. The chemical formula for this hydrate is:
b. The IUPAC name for this hydrate is:

What does earth’s rotation on its axis cause? the tides night and day passing of years phases of the moon

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.

Which common material is an example of a polymer? (25 pts) a. steel b. plastic c. petroleum d. rubbing alcohol