There are 3 dimethylbenzenes (xylenes) - ortho-, meta-, and para-, of course. Without NMR, it is not easy to assign the structures to the correct samples. Assume that you have a pure sample of each isomer. Show how monobromination (Br2/FeBr3) can be used to make the assignment. You should assume that because methyl is only weakly activating you can isolate pure some of each and every possible monobromo isomer for all three reactions and distinguish them by MP.

1. suppose a reaction mixture, when diluted with water, afforded 300 ml of an aqueous solution of 30 g of the reaction product malononitrile [ch2(cn)2], which is to be isolated by extraction with ether. the solubility of malononitrile in ether at room temperature is 20.0 g/100 ml, and in water is 13.3 g/100 ml. what weight of malononitrile would be recovered by extraction with (a) three 100-ml portions of ether and (b) one 300-ml portion of ether? suggestion: for each extraction, let x equal the weight extracted into the ether layer. in part (a), the concentration in the ether layer is x/100 and in the water layer is (30 x)/300; the ratio of these quantities is equal to k 20/13.3.

Which statement correctly describes the phosphate ion, ? it is composed of one phosphorus atom and four oxygen atoms covalently bonded together, and there is a –3 charge distributed over the entire ion. it is composed of one phosphorus atom and four oxygen atoms covalently bonded together, and there is a –3 charge on the phosphorus atom. it is composed of one phosphorus atom and four oxygen atoms ionically bonded together, and there is a –3 charge distributed over the entire ion. it is composed of one phosphorus atom and four oxygen atoms ionically bonded together, and there is a –3 charge on the phosphorus atom.

Which conclusion fits the data in the table? a. heat chemically changes chocolate and margarine. b. all solids become liquid at 100°f. c. removing heat from a substance it to melt. d. matter may change shape when it is heated.