Phosphoric acid, a mild acid used among other things as a rust inhibitor, food additive, and etching agent for cavity repair by dentists, can be made from elemental phosphorus in a two step process. in the first step, phosphorus and oxygen react to form diphosphorus pentoxide: in the second step, diphosphorus pentoxide and water react to form phosphoric acid : suppose the yield of the first step is and the yield of the second step is . calculate the mass of phosphorus required to make of phosphoric acid. be sure your answer has a unit symbol, if needed, and is rounded to the correct number of significant digits.

Calculate the molarity of 48.0 ml of 6.00 m h2so4 diluted to 0.250 l .

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.

Draw the lewis structure for the trisulfur s3 molecule. be sure to include all resonance structures that satisfy the octet rule.