The aim of the experiment is to determine the concentration of phosphate ions in unknown samples. A series of dilution of known concentration is performed from the phosphate working solution. Each of the prepared working standards, the unknown samples and the blank are then made to react with a mixed reagent which have been prepared after acid wash of the glasswares Glassware * 2 Beakers * 11 conical flasks * 9 Volumetric flasks 50 ml * 1 Volumetric flasks 1000 ml * Pipette type 1 Pipette 25 ml * Stir rod * 11cuvette * Spectrophotometer Chemical needs; hazards and safety precautions: 1.
Sulphuric acid It is very hazardous in case of skin contact. It is classified as corrosive, irritant and permeator. Safety needs: Lab coats,safety goggles and gloves should be worn to minimize risk of contact. In case of: •Eye Contact: Check for and remove any contact lenses. In case of contact, immediately flush eyes with plenty of water for at least 15minutes. Cold water may be used. Get medical attention immediately. •Skin Contact:
In case of contact, immediately flush skin with plenty of water for at least 15 minutes while removing contaminated clothing and shoes.
Cover the irritated skin with an emollient. Cold water may be used. Wash clothing before reuse. Thoroughly clean shoes before reuse. Get medical attention immediately. •Serious Skin Contact: Wash with a disinfectant soap and cover the contaminated skin with an anti-bacterial cream. Seek immediate medical attention. •Inhalation: If inhaled, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen.
Get medical attention immediately. 2. ammonium heptimolybdate Ammonium heptimolybdate e is harmful if swallowed or inhaled. It causes irritation to the eyes, skin, and respiratory tract. It affects kidneys and blood Safety measures: Lab coats,safety goggles and gloves should be worn to minimize risk of contact. 3. Potassium antimonyl tartrate Slightly hazardous in case of ingestion. Non-corrosive for skin. Non-sensitizer for skin. 4. Ascorbic acid Slightly hazardous in case of skin contact (irritant), of eye contact (irritant), of ingestion, of inhalation.
Safety measures: Lab coats, safety goggles and gloves should be worn to minimize risk of contact. 5. Hydrochloric acid Concentrated hydrochloric acid forms acidic mists. Both the mist and the solution have a corrosive effect on human tissue, with the potential to damage respiratory organs, eyes, skin, and intestines. The HCL should be used in a fume hood and personal protective equipment such as rubber or PVC gloves, protective eye goggles, and chemical-resistant clothing such as lab coats should be used to minimize risk when handling hydrochloric acid.
Procedures and calculations. * All of the glassware’s to be used are to be washed with acid (HCL) and then with distilled water. * Nine standards, a blank and 2 random sample are going to be analysed. * Prepare a series of working standards in the range of 10-500µg NO2-N/L * To 50 cm3 of each working standard and sample add 1. 0 cm3 of sulphanilamide, mix and stand for 2 minutes Calculations 1ml = 0. 5 µg of NO2- 1000 ml of solution contain = 10 ml of NO2- (100 µg) 50 ml of solution contain = 1 ml of NO2- (10 µg)
SN| Volume of standardPHOSPHATE solution (s)| Volume ofwater| Concentration| Absorbance| 1. | 1. 0| 49| 10| 0. 003| 2. | 2. 0| 45| 50| 0. 035| 3. | 3. 0| 40| 100| 0. 058| 4. | 4. 0| 35| 150| 0. 074| 5. | 5. 0| 30| 200| 0. 099| Blank| 0| 50| 0| 0. 000| Sample A1| | 0. 022| Sample B1| | 0. 068| Result A Graph of absorbance (OD) against concentration (µg). Using the equation (y=mx+b) to determine concentration of samples. Let “Y” equal the concentration. This is what will be solved for. Let “X” equal the absorbency of the sample.
This is the absorbency measured by the spectrophotometer Allow “to equal the slope and “b” to equal the y-intercept y= 0. 019 x + 0. 947 Concentration of Sample 1 Absorbance of sample A1 = 0. 022 y= 0. 019 (0. 022) + 0. 947 = 0. 947 Concentration of unknown sample 2 Absorbance of sample B2 = 0. 068 y= 0. 019 (0. 068) + 0. 947 = 0. 948 Discussion The concentration phosphate ion in of samples D and E were determined In this experiment I determined the concentration of phosphate ion in samples D and E.
These values were determined by obtaining data from solutions of known concentration. These solutions were placed in the spectrophotometer and then by plotting a graph of absorbance vs. concentration, an equation was produced from which the unknown concentration were determined Conclusion From the result of the experiment, it was determined that the relationship between concentration and absorbance is linear. The amount of light absorbed by a solution varies directly with solute concentration.