0.1575 g of anhydrous potassium dihydrogenphosphate are used to prepare 500 mL o
ID: 888448 • Letter: 0
Question
0.1575 g of anhydrous potassium dihydrogenphosphate are used to prepare 500 mL of the 50 mg/L (approximate) stock solution of P. The instructions guide you to make a subsequent STANDARD P solution. Following the procedure described in the lab manual, what is the volume you must use of STANDARD P solution to make a 100 ?g/L P standard?
The answer is 1.395, but I don't find the way to get that answer. The manual instructions are above. Thanks!
The laboratory spectrophotometers use 1.0 cm path length cuvets, which suggests a . ssiam concentration range of 0.15-1.30 mg P/L is concentration range of appropriate for your calibration curve; however, the spectrophotometers we use are better than a Principle: Ammoeium molybdate and astimeay potassiam urtrate react in acid medium with -senely colored produce a blue color similar to acid-that is redaced to in- those used to set these limits. You will be able b. Interference: Arsenates react with the molybdane reagent to at formed with pla spate. as low as Q.1 mg AsL inserfere with the phos- detect phosphorus concentrations below 0.15 mg P/L. Your calibration curve should range from chromiun and NO" interfere 0.1 to 2.0 mg P/L togivo results about 3% low at concettations of 1 mg. and 10 to 5% low 10 mp. SalSde aaS) ad ,late do Save your stock phosphate solution and * of 1.0 and 10 mg/l standard phosphate solutions. Do not discared them. These solutions may be used for later labs and the laboratory project e, Miinam deseenable concentrain. Approximately 10 P/L. P ranges are as follows 4500-P.C.2b. Acid-washed glassware Use acid- washed glassware for determining low concentrations of phosphorus. Phosphate contamination is common because of its using commercial detergents containing phosphate Clean all glassware with hot dilute HCI and rinse wel ion on glass surfaces. Avoid a Celorimetrie equipment One of de following is required:with distilled water. Preferably reserve the glassware only for phosphate determination, and after use, wash nm providing a light pah of 2.3 em or longe 2) Pher phomer, equipped witha red color ther andand keep filled with water until needed. If this is done, light path ot 03 em or longee acid treatment is required only occasionally See Section 4300-P.C.2B 1 M HCI will be available in the laboratory for 1 MHCI will be available in the laboratory for . acid washing glassware artrate solanion: Dissolve 1.3715You will need to prepare Reagent a (S N H,sO.) Asiony potasais sartmate solation: Dissolve 1.3715 K( O)LO. WHO in 400 ml. distilled water in a 300-mL volumetrie Cask and dJute to volume. Ssore in a glass-stoppered using 9 M H SOs, instead of concentration H:SO Normality, N, is moles of reactive unit per liter For H SO4, H is the reactive unit, so 1 M H SO4 is e Ammoniam mobbdane solution Dissolve 20 s NIL),Mo,Op. 4HO in 500 ml discilled wacer. Store in a 500 mL diseilled waser Stoe in 2N HSO Reagents b, c, and d will be prepared for you d Aucorbic acid O1M: Dissolve 1.76 g ascorbic acid in 100 ml. distilled water. The solution is stable foe about 1 week at When preparing Reagent e, the Combined reagent, the reagents must be added in the order listed and mixed after each reagent is . e. Combined reagent: Mix the above reageets in the fol- lowing proportions for 100 mL of the combined mL. SN HSO. 5 ml antimony potassium tartrace solution, 15 m molybdate solution, and 30 ml. ascorbic acid solution. Afix ofher addition of each reagent. Let all reageots reach room temperature before they are mixed and mix in the ium molybdate sobution, and 30 ml. ascorbic acid added in order for the proper chemistry to occur Make sure you have recorded his information correctly in your notebook. Reagent f. The directions ask you to prepare 1 L of this stock solution; you only need to prepare order given. If turbidity forms in the combined reagent, shakec and let stand for a few minutes until turbidity disappears . before procceding. The reagent is stable for 4 h A Stock phosphate solation: See Section 4500-P.C.3 Standard phosphane solanion: Diute 500 ml. stock phosphate solution to 1000 mL with fulled waxci.00 m. . 250 P 4500-P.C.3e. Dissolve in distilled water 219.5 mg anhydrous KH POs and dilute to 1000 mL; 1.00 ml 50.0 PO--P Reagent g. Prepare 1 L of this solution. .Explanation / Answer
we are diluting the standard solution.
100g/L is 0.1mg/L
we need 500ml of 0.1mg/L solution
we have 500 mL of the 50 mg/L stock solution of P
volume of stock solution of P=500mlx0.1mg/L/50mg/L=1ml
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.