After 10.0 mL of an aqueous solution containing 1.235 mg of a drug extracted with 5.0 mL of toluene the aqueous layer was found to contain 0.346 mg of the compound. (a) Calculate the distribution coefficient for the drug between the two solvents.  (b) How many 10.0-mL extractions would be required to recover 99.0% of the drug from 20.0 mL of water?  What volume of toluene would be used?

(d) A sample contains a mixture of ammonium carbonate (NH4)2CO3, sodium carbonate Na2CO3, and sodium chloride NaCl. Thermogravimetric analysis indicates that a 0.0965-g portion of this sample loses 0.0574 g over a temperature range of 50-75 oC and then loses another 0.0124 g at 800 oC.(i) What causes the weight loss at 50-75 oC? (ii) What species will remain after being heated to 800 oC? (iii) What is the composition of the original sample?  Given: Atomic masses: H = 1.008; C = 12.011; N = 14.007; Na = 22.99; O = 15.999;Cl = 35.45.

Exactly 5.00-mL aliquots of a methanol solution containing an unknown amount of methamphetamine were measured into 50.00-mL volumetric flasks. The following volumes of a standard methanol solution of methamphetamine containing 2.000 ug/mL of methamphetamine were then introduced into each flask and the mixture was diluted to volume with 0.000, 0.500, 1.00, 1.50 and 2.00 mL of methanol. 1 uL of these solutions was then injected into a gas chromatograph and the following respective peak areas were measured: 326, 480, 641, 802, and 956 (all peak areas were x 103).   Plot the data Using the plot from (a), calculate the concentration of methamphetamine in the unknown. Derive a least squares equation from the data. Calculate the concentration of methamphetamine from the equation in (c).

Oral rehydration salts are stated to contain the following components: Sodium Chloride  3.5g Potassium Chloride  1.5g Sodium Citrate  2.9g Anhydrous Glucose  20.0g 8.342 g of oral rehydration salts are dissolved in 500 ml of water. 5 ml of the solution is diluted to 100 ml and then 5 ml is taken from the diluted sample and is diluted to 100 ml. The sodium content of the sample is then determined by flame photometry. The sodium salts used to prepare the mixture were: Trisodium citrate hydrate (C6H5Na3O7, 2H2O) MW 294.1 and sodium chloride (NaCl) NW 58.5. Atomic weight of Na = 23. The content of Na in the diluted sample was determined to be 0.3210 mg/100 ml. Determine the % of stated content of Na in the sample.