A 25.0 mL sample of waste water is obtained to analyze for Pb2 ions. This sample is evaporated to dryness and redissolved in 2.0 mL of H2O, mixed with 2.0 mL of a buffer solution and 2.0 mL of a solution of dithizone then diluted to 10.0 mL. The absorbance of the colored Pb2 - dithizone complex is compared with the Beer-Lambert plot below. 8. The absorbance of a portion of the final solution is 0.13. What is the concentration of Pb2 ions in the waste water in ppm

__ _ _ _ _ is the process of removing earth materials from their original sites through weathering and transport and depositing the in another location. a. erosion b. sedimentation c. lithification d. dissolution

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.

In a water molecule, hydrogen and oxygen are held together by a(an) bond. a) double covalent b) ionic c) nonpolar covalent d) hydrogen e) polar covalent