9. Acidity in Water and Waste Water Introduction:
Acidity of water is its quantitative capacity to react with a strong base to a designated pH. Strong mineral acids such as carbonic acid and acetic acid contributes to acidity of the water while dissolved carbon dioxide (CO2) is the major acidic component of unpolluted surface waters. Acidity (or base-neutralizing capacity) in water and waste water is the measure of acid radicals produced by the dissociation of acid present in the sample. This is determined by titrating an acid wastewater (pH<7) with a strong base. Industrial wastewaters containing high mineral acidity should be properly neutralized before they are subjected to biological treatment or direct discharge due to the following
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If the pH is less than 6.0, it must be boiled for 15 minutes and cooled at room temperature. (c) Sodium hydroxide solution (0.02 N): 1N sodium hydroxide solution is prepared by dissolving 40 g of L.R grade NaOH in distilled water and diluting it to 1000 ml. For the preparation of 0.02 N NaOH solution, take 20 ml of IN NaOH and dilute it to 1000 ml. 0.02 N NaOH can be standardize against standard potassium acid phthalate. 1.0 ml 0.02 N NaOH = 1.0 mg CaCO3
(d) Phenolphthalein indicator: Dissolve 0.5 g of phenolphthalein in 100 ml alcohol and water.
(e) Methyl orange Indicator: Dissolve 0.5 g of methyl orange in distilled water and dilute it to 100 ml in a volumetric flask.
Procedure:
Indicator Method: Pipette 20 ml or a suitable aliquot of sample into a 100 ml beaker. Divide the sample water into two parts and determine the pH of two parts. If pH is less than 3.7, add two drops of methyl orange indicator into the first sample beaker and titrate with standard 0.02 N sodium hydroxide solution until the color changes to the faint orange. Record the volume of sodium hydroxide consumed to neutralize H+ ions. To the second sample beaker, add 2 or 3 drops of phenolphthalein indicator and titrate with 0.02 N sodium hydroxide solution until the color changes to faint pink color. Record the volume of sodium hydroxide used to neutralize
A hot plate was placed under the ring stand. 50 mL of 3.0 M NaOH in a 250 mL beaker and a stir bar was placed in the beaker. The beaker with NaOH was placed on the hot plate and 3.75 grams of NaAlO2*5H2O was placed in the beaker. The temperature probe was placed in the beaker with the solution, not touching the bottom of the beaker. The solution was heated and stirred till the solution dissolved.
Marwah Alabbad Post lab 10/21/15 Question 1: 1. Experiment 1: Number of trails NaOH concentration (M) Volume of HCl solution (mL) Initial volume of NaOH(mL) final volume of NaOH(mL) The volume of NaOH to titrate HCl (mL) Concentration of HCl (M) 1st 0.1023 25.0 10.05 36.12 26.07 0.085 2nd 0.1023 25.0 5.74 31.40 25.66 0.105 3rd 0.1023 25.0 9.84 35.52 25.68 0.105 First trail calculation: 0.02607L× (0.1023mole NaOH/1L)×(1 mol of HCL/1 mol of NaOH)×(1/0.025)= 0.085M of HCl
The anion tests followed the cation tests. To test for the presence of the chloride (Cl-) anion, a small scoop of the unknown compound was mixed with 1 mL of water in a test tube to create a solution. Then, 1 mL of 6 M nitric acid (HNO3) and 1 mL of silver nitrate (Ag(NO3)2) solution were added to the test tube to see if a white precipitate formed. To test for the presence of the sulfate (SO42-) anion, a small scoop of the unknown compound was mixed with 1 mL of water in a test tube to create a solution. Then, 1 mL of 6 M hydrochloric acid (HCl) and 1 mL of barium chloride (BaCl2) solution were added to the test tube to see if a white precipitate formed.
Two titration were performed for each buffer: HCl and NaOH. A pH meter was used to record the pH change, and the volume of the buret was recorded every .1 change in pH. This potentiometric titration method was stop once the solution change by 2 pH units. The
Step 2: Mix both test tubes , shake gently and time the reaction. Step 3: The same step as procedure 1, and step 3 which is to record the observed color step 4: use the palette/color chart to help you identify the observations you make. Safety precautions: Pull your hair back Safety eye goggles Closed toe
I organized four different tests; pH paper, alkalinity tests, the number of rocks neutralizing acid, and the number of rocks that don’t neutralize acid. The average for pH paper was seven. The pH is the numeric scale used to specify the acidity or alkalinity of an aqueous solution. The pH scale measures acidity and alkalinity. the pH scale goes from zero, which is an acid reading, to fourteen, which is an alkaline reading.
Weighed 1 gram of NaC2H3O2 and mixed it with ionized water. Boiled 12 mL of 1.0M Acetic Acid added into a beaker containing the sodium carbonate on a hot plate until all the liquid is evaporated
Standard Sodium hydroxide solution is the alkaline solution that will be used to titrate with soda water as it is a common solution that can be easily found in an ordinary school laboratory. It is a strong base. Carbonic acid is a weak acid which will react with a strong base to form a basic (pH > 7) solution. When Phenolphthalein is added to Soda water, the resultant solution is colourless. After titration with a strong base (sodium hydroxide), the solution will turn to pink as the solution becomes
Conclusion: Based on the results of molarity from Trials 1, 2, and 3, it is concluded that our experimental for each trial is .410M NaOH, .410M NaOH, and .450M NaOH. The actual molarity of the NaOH concentration used was found to be 1.5M NaOH. The percent error of the results resulted in 72%. The large error may have occurred due to over titration of the NaOH, as the color of the solution in the flask was a darker pink in comparison for the needed faint pink. Discussion of Theory:
Determination of Vitamin C Concentration by Titration Serena Kim Vasantha Susarla McGill University Introduction This experiment is being performed to determine the concentration of Vitamin C in different solutions by performing a redox reaction with potassium iodate. Vitamin C, which is also called ascorbic acid, can be naturally found in citrus fruits and common vegetables. Vitamin C is considered as an antioxidant because it acts as a coenzyme and reducing agent in several different ways.
Background Information: All cells are covered by cellular membranes. They are selective barriers which permit the selective passage of water, ions and other molecules between the cell and the outside solution. When two solutions having different concentrations of ions and molecules are separated by a semipermeable membrane, there will be some exchange between them. This will happen because they tend to equilibrate the concentrations and the osmotic pressure of the solutions, in order to be the same for both of them.
The equation of the reaction between sodium hydroxide and ethanoic acid is as follows: CH3COOH + NaOH → CH3COONa + H2O We can measure the end point of titration process and we can also measure the amount of reactants. The concentration of ethanoic acid in the vinegar can be determined through stoichiometric calculations, Using the values obtained from the titration, and also the chemical equation as a reference. Phenolphthalein indicator is used in this acid-base titration Equipment and materials:
Strong acids and strong bases are strong electrolytes and are assumed to ionize completely in the presence of water. Weak acids however, only ionize to a limited extend in water. Any weak or strong acids when in contact with any weak or strong alkali will start to undergo neutralization regardless of their volume. When an indicator which is present in the acid-base mixture and have experienced colour change, it indicates that the mixture is in right proportions to neutralize each other and is also known as the equivalence point.
The average result obtained was 22.5% and is close to it’s literal value. This experiment had also proven to have shown effective transfer of solids and liquids as values of 1st and 2nd results, namely 22% and 23% respectively, were similar thereby showing consistency in results. Phenolphthalein indicator was proven to be more suitable as an indicator as compared to Methyl Orange in this experiment. This is because Phenolphthalein the pH values of HCl involved in this experiment were in range of the pH values that bring about colour change in the Phenolphthalein indicators. (Approximate pH ranges for color change: 8.0-9.8) Low pH values are preferred for Methyl Orange.
The chemical equation for this experiment is hydrochloric acid + sodium thiosulphate + deionised water (ranging from 25ml to 0ml in 5ml intervals) sodium chloride + deionised water (ranging from 25ml to 0ml in 5ml intervals) + sulphur dioxide + sulphur. As a scientific equation, this would be written out as, NA2S2O3 + 2HCL + H2O (ranging from 25ml to 0ml in