The main indicator of efficiency of extraction is the distribution coefficient. It calculates by a formula: With / Sv, where With – concentration of the extracted substance in organic solvent (extractor), and Sv – concentration of the same substance in water, after balance approach. How it is possible to find distribution coefficient by practical consideration?
It is required to you
- - laboratory capacity;
- - solution of acetic acid;
- - diethyl fir;
- - water;
- - stopper;
- - sodium hydroxide solution;
- - dividing funnel.
Instruction
1. Such task is set for you. Solution of acetic acid of the known concentration, ethyl oxide, test (titrating) solution of alkali – sodium hydroxide and also indicator solution - phenolphthalein is given. It is necessary to calculate substance distribution coefficient – acetic acid – between ethyl oxide and water. How to make it?
2. In laboratory capacity (for example, a flat-bottomed flask with shlify) pour some volume of solution of acetic acid of-50 ml. Then add the same volume of ethyl oxide to the same flask, densely close a "prishlifovanny" stopper and several minutes stir up mix (manually or by means of a rocking chair).
3. After stirring take a break for 15 – 20 minutes (you will distinctly see how mix will be stratified). Repeat stirring. This procedure it is necessary to do a minimum twice, for fuller extraction of acetic acid and, respectively, more exact result.
4. During first "upholding", carry out control titration of a number of solution of acid by sodium hydroxide solution in the presence of the phenolphthalein indicator. Write down how many milliliters of alkali left on neutralization, having designated this size C1.
5. After last "upholding" of mix when the clear boundary of the section of phases is shown, carefully pour in a dividing funnel. Having rejected the lower faucet, select heavier water layer. It still contains acetic acid, but, certainly, in smaller concentration – a part it was extracted by air.
6. Select just the same amount of solution of acid, as well as at control titration, and again an ottitruyta its caustic natr in the presence of phenolphthalein. The quantity of milliliters of alkali spent for neutralization designate C2. Calculate coefficient of distribution by a formula: C1/C2. The task is solved.