Test+7+-+Ortho-+and+Total+Phosphates

__//**Ortho- and total Phosphatesb**//__
Wastewater has a lot of phosphorus compounds. Phosphorus is a nutrient used by organisms to help them grow. It occurs in natural water and wastewater bound to oxygen to form phosphates. Phosphates come from a variety of sources including fertilizers, domestic wastewater, detergents, industrial process wastes and geological formations.

The discharge of wastewater containing phosphorus causes algae growth in quantities sufficient to cause taste and odor problems in drinking water. Dead and decaying algae can cause oxygen depletion problems which in turn can kill fish and other aquatic organisms in streams. Because of this industries are trying to find ways to stop phosphorus.

// You can found phosphours in rocks and mineral deposits. When weathering happens the rocks will slowly relase phosphours in the form of phosphates. Phosphates can be found in three forms: orthophosphate, metaphosphate, and organically bond phosphates with different chemically properties. // // They are found in living and decaying or animal remines as weak chemical bonds that bond wiht the sediment of the soil. Orthophosphate is made from natural processes, and the organic phospate is made from the plant tissue compounding with the phospate. //

b. Add 2.0mL of 2.63 M H2SO4 to each flask using 10 mL graduated cylinder and swirl. WARNING: USE THE SULFURIC ACID WITH CARE.
=== c. Boil the samples for 30 mintues, adding small amounts of distilled water to keep the volume near, but not above 25mL. WARNING:MAKE SURE YOU ARE BOILINGIN WELL VENTILATED AREA. DO NOT BREATHE THE FUMES GENERATED BY THIS DIGESTION. ===

9. Prepare the computer for data collection by opening the file "07 Phosphates" fomr the Water quality with Vernier experiment files of logger pro.
=== 10. Prepare a blank by filling an empty cuvette 3/4 full with distilled water. Seal the cuvette wiht a lid. To correctly use a colorimeter cuvette, remember, : all civettes should be wiped clean and dry on the outside with a tissue, handle cuvettes only by the top edge on the ribbed sides, all aolutions should be free of bubbles. always postion the cuvette wiht its reference mark facing toward the with reference mark at the top of the cuvette slot on the colorimeter. ===

b. Holding the cuvette by the upper edges place it inthe cuvette slot of the Colorimeter. Close the lid.
=== c. If your colorimeter has a CAL buttion, press the buttion on the colorimeter to selet a wavelength of 565 nm (Green) for this experiment. Press the CAL buttion untiull the red LED begins to flash. Then release the CAL buttion. WHen the LED stops flashing the calibration is complete. === === 12. Collect absorbance-concentration data for the blank and the phosphate standard solution. This process will creat a standard curve that will be used to determine the phospate concentrations of the samples. ===

c. Type 0 ( the phosphate concentration ) in the edit box, then press enter.
=== d. Discard the water in the cuvette. Rinse twice with the standard solution from the Flask "S" and then fill it 3/4 full. Wipe the outrside of the cuvette and place it in the colorimeter. After closing the lid, wait for the absorbance value displayed in the meter to stabilize, then click keep. ===

f. Click stop.
=== 13. Examine the graph of absorbance vs. concentraion. To see relationship between these two variables, click on the Linear Fit button. A linear regression curve will be shown for your data pionts. This line should pass through the data pionts and the on or near the origin of the graph. ( Note: Another options is to choose Curve Fit from the Analyze menu, and then select Proportional. The Proportional fit, ( y=Ax) has a y-intercept value equal 0; therefore, this regression line iwll always pass through the orgin of the graph). ===

b. Observe the absorance value in the meter. When the absorbance value has stabilized, record it on the Data & Calculations sheet.
=== 16. Use the following method to determine the unknown concentration. With the linear regession curve still displayed on your graph, choiose Interpolate from the Analyze menu. A vertical cursutr now appears on the graph. The cursor's x and y coordinates are displayed in a floating box. Move the cursor along the regression line untill the aborbance (y) value is approximately the same as the absorbance value you recorded in Step 15. The corresponding x value is the concentration of the unknowsolution in mg/L PO4. Record this value in Column B on the Data & Calulations sheet. ===

17. Repeat Steps 15-16 for Flask B.
=== 18. The values obtained in Step 16 are in units of mg.L phosphorus, PO4-P. If you wish to convert your phosphate values to phosphorus, use this equation and record the results in Column C of the Data & Calculations sheet ===

**// Flask //** ||    **// Absorbance //**  ||  **// Total Ortho //** **// Phosphates Concentration //** **// ( mg/L PO4 ) //** ||  **// Total Ortho //** **// Phosphorus Concentration //** **// ( mg/L PO4-P ) //** ||
 * **// Colum //** ||  **// A //**  ||  **// B //**  ||  **// C //**  ||
 * **// A //** ||   ||   ||   ||
 * **// B //** ||   ||   ||   ||
 * **// Average //** ||   ||   ||   ||