Acid nuterlizing capacity of water is called aklalinity .it can be determine by titration method by using methyl orange and phenolphthalein .
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a Formal Report on a colorimetry experiment under Analytical ChemistryDescripción completa
a Formal Report on a colorimetry experiment under Analytical ChemistryFull description
Extraction-of-copper-pdf
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In recent years, the employability of students has become one of the main responsibilities of all university institutions. Universities have evolved from being inbred to begin to refer increasingly to society Universitat Polité:cnica de Valencia, 201
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Determination of Dissolved Oxygen in Water Using the Winkler Method
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Expt.no.3 Determination of percentage of copper in brass sample Procedure: Patr A: Preparation of brass solution Weigh accurately about 0.1 gram of given sample and transfer it in to a conical flask add 3ml of con HNO3, and heat till alloy dissolves completely add 2tt of water boil and then add about 1g or urea, and boil till the brown fumes of oxides of nitrogen are completely expelled , cool in tap water Part B: Estimation of copper Burette : Sodium thio sulphate Conical flask : Brass + Aqueous Ammonia (till pale blue ppt) + Dilute Acetic acid (till blue ppt disappears) + 5 more cc of acetic acid + 100 cc of 10g of KI Indicator : Starch solution nearly at the end point . End point : Disappearance of blue color leaving a white ppt From the volume of sodium thio sulphate solution run down from the burette, calculate the percentage of copper present in brass sample
Determination of percentage of copper in brass using standard sodium thiosulphate solution Procedure: - weigh accurately brass sample 0.1 g in to a clean dry conical flask .Add 3ml of con HNO 3. When brass completely dissolves , add 1g of urea , 2tt of distilled water and boil the solution till the oxides of nitrogen are completely expelled. Cool the solution add drop wise ammonium hydroxide till a permanent bluish white ppt of cupric hydroxide is obtained. Add acetic acid till the precipitate just dissolves. Add 1tt of 10% of KI titrate the liberated iodine against the standard sodium thiosulphate solution taken in the burette tile the color of the solution is pale yellow . Add 1ml of starch indicator and titrate further till a milky white w hite ppt persists . Repeat the procedure with another sample of brass. Let the volume of the sodium thiosulphate consumed be X ml Weight of brass(g) FBR IBR Vol of thiosulphate
1
2
3
0.0
0.0
0.0
Weigh of brass =wg, vol of sodium thiosulphate = Xml Normality of sodium thiosulphate = 0.03X 1000ml of 1N Na2s2O3 = 63.54g of cu(eq.wt of cu) Xml of 0.05N Na 2c2O3 =
= Ygm of cu
Wg of brass contains Y gm of cu. 100g of brass contains
Result :- % of cu in given brass sample is __________% VIVA 1. What are the constituents of brass? Brass is an alloy of cu (60 80%) and Zn(20 40%) with small amount of sn, pb and fe 2. What is the purpose of adding urea in the ex periment? To destroy excess HNO3 and completely remove the oxides of nitrogen 3. Why acetic acid is added ? To neutralize excess of NH4OH and to make the solution slightly acidic 4. What is the role of NH 4OH? NH4OH is added to neutralize excess of HNO 3 is not removed, it would oxidize iodine to iodic acid and decompose sodium thio sulphate
Expt.no.4 Determination of chemical oxygen demand (COD) from a waste water sample Procedure : Prep ration of standard ferrous ammonium sulphate (FAS) Weigh out given FAS crystals and transfer in to a clean standard flask. To this add 1tt of dilute sulfuric acid and make it up to mark by adding distill water, mix well.
NFAS = W X 4/m = ____________N = (M is mol.wt = eq.wt of FAS = 392) Part - A Burette = FAS solution Conical flask = 25ml of waste water sample + 10ml of pot assium dichromate + 1tt of sulphuric acid Indicator : Ferroin indicator End point : Bluish green to reddish brown Part B Blank titration :- (The value will be given by the examiner)=28cc From the difference in value run down (FAS) from the blank and with waste sample the COD of waste water sample is determined. Determination of COD from the waste water sample Preparation of standard FAS solution 3
Weigh around 4.8gm of FAS into a 250cm volumetric flask. Add 1ml of con H 2SO4 and swirl the flask to dissolve the crystals. Make up the solution with distilled water and calculate the normality of FAS . 3
Transfer 25ml of waste water sample into 250cm conical flask. Add 10ml of standard potassium dichromate solution followed by 1tt full or 5ml of 1:1 sulphuric acid containing silver sulphate with constant shaking of contents of the flask. Add three drops of ferroin indicator and titrate against FAS solution until the solution turns from blue green to reddish brown. For balance titration add 10ml to the obtained burette value. Observations and calculations :Preparation of FAS solution 1. Weight of weighing bottle + FAS crystals = _________gms. 2. Weight of weighing bottle
= _________gms.
Weight of FAS crystals (W)
= _________gms.
NFAS = W X 4 / Eq. wt. = Z
[Eq. wt. of FAS=392 ]
Burette readings: - [Y] Trail - 1
Trail - 2
Trail - 3
FBR IBR VRD
Calculations Normality of FAS = X ml Volume of FAS
= Y ml
1000ml of 1N FAS = 8000mg of oxygen Z = balance titrate value
(Z-Y)ml of X N FAS =
M mg of oxygen
25ml of waste water contains M mg of oxygen 1000ml of waste water contains =
= ________mg of oxygen.
VIVA 1. Chemical oxygen demand is the amount of oxygen in mg required to oxidize by strong chemical oxident to organic and inorganic materials present in 1000cc of waste water. 2. BOD is the amount of oxygen required for the biological oxidation for organic matter during 0
aerobic condition 20 c for a period of 5 days. 3. The oxidizable impurities of waste water are straight chain alcohol, acids. 4. The indicator used to determine the COD of waste water is ferroin. The color change at the equivalence point bluish green to reddish brown.
Determination of dissolved oxygen in water by winklers method
Procedure: In a winklers bottle take drain water apply stopper. Takeout 10cc of water, add 2cc of manganous sulphate and 2cc of alkaline KI solution stopper and shake well for 10 minutes then 30 drops of con. sulphuric acid and shake well for 5 minutes . Titrate librated iodine by pipetting 50cc of solution from the bottle against 0.01Nsodium thiosulphate solution. 1
2
3
FBR IBR VRD (Xcc)
1000cc of 1N Na2 S2O3 = 8g of O2 Xcc of 0.01N =
= a grams of O2
50cc of water = a grams of O 2 6
6
10 cc of O2 or ppm (grams of dissolved oxygen in 1 million cc of water ) (8000 mg o f oxygen in 10 cc of water) VIVA 1.
BOD is the number of grams of free oxygen required to oxidize organic matter in a sample of drain water under aerobic conditions at 20 c. in a period of 5 days.
2. BOD is mentioned as No . of grams or milligrams of oxygen required for the biological oxidation of impurities present in 1000cc of water or ppm, i.e., No. of grams of oxygen required for aerobic oxidation of oxidizable impurities present in 1 million or 106cc of water.
Expt No :10
COCLOROMETRIC DETERMINATION OF COPPER Procedure: Draw out 5,10, 5,20 ml of given copper sulphate solution in to a 4 separate 50ml volumetric flask. Add 5ml of ammonia solution to each one of them and also in to the test solution of unknown concentration and dilute up to the mark by adding distill water and mix well. Adjust the absorbency to zero using blank solution (only ammonia and water). Plot a graph of absorbance (OD) against volume of copper sulphate and determine the volume of given copper sulphate solution and weight of copper in it.
OBSERVATIONS AND CALCULATIONS. Volume of copper Sulphate Blank solution
Absorbency or Optical density 0.00
5ml 10ml 15ml 20ml Unknown solution [X ml] 1000 cc of copper sulphate contains solution 4 gms of CuSO4 X cc of copper sulphate contains = 4 x X/1000 = _________ a gms of CuSO4 250 gms of copper sulphate contains = 63 gms of Cu. a gms of copper sulphate contains = 63 X a/250 = _________ gms of copper.
VIVA: 1. When a monochromatic light intensity Io is passed through a transparent medium a part Ia is absord, a part is reflected Ir and remaining is transmitted It such that Io = Ia+ Ir+It For glass air interference Ir is negligible. Therefore, Io = Ia + It
2. Transmittance is It/Io 3. Absorbency or optical density is log [I o/It] 4. Lambert beer law is A = Log[Io/It] = ct. A is absorbency, is a constant, its value depends on the nature of transparent substance and wavelength; it is also called as molar extinction coefficient. C is a concentration and t is t he pass length
5. Pass length is thickness of the medium or the distance of the light passes in the transparent medium and is also called cell thickness, its unit is cm. -1
