...Module 9 : Experiments in Chemistry Lecture 38 : Titrations : Acid-Base, Redox and Complexometric Objectives In this lecture you will learn the techniques to do following Determination of the amount of sodium carbonate and sodium hydroxide in a mixture by titration. Carrying out acid-base titration using a pH meter. Carrying out acid-base titration by conductometric measurement. Determination of the composition of a mixture of acetic acid and hydrochloric acid by conductometric titration. Determination of ferrous ion using potassium dichromate by internal indicator. Determination of hardness (Ca2+ ) of water using EDTA – complexometry method. In this lecture, you will be introduced to a few experiments in chemistry. These experiments complement the theory you have learned in chemical equilibrium and kinetics. 38.1 Acid-Base Titrations: Acid-base reactions are of great practical importance in analysis, not only because of their use in titrating a large number of inorganic and organic substances, but also because the hydrogen ion concentration of a solution often is of great importance in controlling reactions. Titration : The process of determining the volume of a given solution of a reagent equivalent to the amount of another reactant present in a standard solution is known as titration. Equivalent Weight of Acids and Bases : The equivalent weight of an acid is that weight which yields one mole of hydrogen ions in the reaction employed whereas the equivalent weight of...
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...labelled “0.05 M acetic acid.” A 10 mL graduated cylinder was used to add 5 mL of 0.5 M acetic acid to the beaker, and the solution was stirred with a glass stirring rod, which was clean each time after use to . Then, a 100 mL of 0.5 M NaOH solution were prepared with the help of a 50 mL graduated cylinder to add 90 mL deionized water to a 250 mL beaker labelled “0.05 M NaOH.” A 10 mL graduated cylinder was used to add 10 mL of 0.5 M NaOH to the beaker, and the solution was stirred. After, the LabQuest and pH probe were prepared for data...
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...Discussion: Table one shows the results from the Standization of NaOH. The table shows that the molarity of NaOH found during the lab was very accurate because it was only 3.05% off of the true value of NaOH which was 0.197M. The first and third trial were very accurate to the true value while the second trial was 0.0134M off of the true value. Trial 2 caused the tests to not be precise because the amount of NaOH was too high and the solution went past the equivalent point. KHP was used in the titration because it has a mole to mole ratio with NaOH of one to one. It was also used because it is easy to measure the mass of KHP and dissolve it in H2O. The molarity of NaOH had to be found using a titration technique because it is not possible to measure the mass of NaOH because it will absorb H20 in the atmosphere and cause an error in the mass. Once the molarity of NaOH is found, it can be used...
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...(Na2CO3) and sodium hydroxide (NaOH) in a mixture Objective To determine the respective weight per cent of sodium carbonate and sodium hydroxide in a mixture by acid-base titration. Result and calculation Part A Titration 1 Titration number 1 2 3 Initial volume of burette( cm3) 5.10 2.70 9.70 Final volume of burette (cm3) 34.40 31.80 39.20 Total volume of HCl used (cm3) 29.30 29.10 29.50 Average volume of HCl required for titration =(29.30+29.10+29.50)/3 cm3 = 29.30 cm3 Titration 2 Titration number 1 2 3 Initial volume of burette( cm3) 4.50 14.00 2.70 Final volume of burette (cm3) 25.00 21.70 22.80 Total volume of HCl used (cm3) 20.50 20.30 20.10 Average volume of HCl required for titration =(20.50+20.30+20.10)/3 cm3 = 20.30 cm3 Part B Titration number Rough 1 2 3 Initial volume of burette( cm3) 4.9 4.80 3.60 2.20 Final volume of burette (cm3) 28.3 28.90 27.70 26.20 Total volume of HCl used until phenolphthalein decolourised (cm3) , x 23.4 24.10 24.10 24.00 Initial volume of burette after adding methyl orange indicator ( cm3) 28.3 28.90 27.70 26.20 Final volume of burette (cm3) 34.1 33.40 32.10 30.70 Total volume of HCl used until phenolphthalein decolourised (cm3) , y 5.8 4.50 4.40 4.50 Average volume of HCl required to react with Na2CO3 (2y) =2(4.50+4.40+4.50)/3 cm3 = 2(4.4667) cm3 =8.9333 cm3 Average volume of HCl required to react with NaOH (x-y) =(24.10+24.10+24...
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...Acid-Base Titration: Determination of the Percentages (%) of Sodium Carbonate (Na2Co3) and Sodium Hydroxide (Naoh) in a Mixture Title Acid-base titration: Determination of the percentages (%) of sodium carbonate (Na2CO3) and sodium hydroxide (NaOH) in a mixture Objective To determine the respective weight per cent of sodium carbonate and sodium hydroxide in a mixture by acid-base titration. Result and calculation Part A Titration 1 Titration number 1 2 3 Initial volume of burette( cm3) 5.10 2.70 9.70 Final volume of burette (cm3) 34.40 31.80 39.20 Total volume of HCl used (cm3) 29.30 29.10 29.50 Average volume of HCl required for titration =(29.30+29.10+29.50)/3 cm3 = 29.30 cm3 Titration 2 Titration number 1 2 3 Initial volume of burette( cm3) 4.50 14.00 2.70 Final volume of burette (cm3) 25.00 21.70 22.80 Total volume of HCl used (cm3) 20.50 20.30 20.10 Average volume of HCl required for titration =(20.50+20.30+20.10)/3 cm3 = 20.30 cm3 Part B Titration number Rough 1 2 3 Initial volume of burette( cm3) 4.9 4.80 3.60 2.20 Final volume of burette (cm3) 28.3 28.90 27.70 26.20 Total volume of HCl used until phenolphthalein decolourised (cm3) , x 23.4 24.10 24.10 24.00 Initial volume of burette after adding methyl orange indicator ( cm3) 28.3 28.90 27.70 26.20 Final volume of burette (cm3) 34.1 33.40 32.10 30.70 Total volume of HCl used until phenolphthalein decolourised (cm3) , y 5.8...
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...US 20070187636Al (19) United States (12) Patent Application Publication (10) Pub. No.: US 2007/0187636 A1 Yamamoto (43) Pub. Date: (54) BOROHYDRIDE FUEL FORMULATION (76) Inventor John Hiroshi Yamamoto Aug. 16, 2007 Related US. Application Data (60) Andover, MA (US) Provisional application No. 60/774,253, ?led on Feb. 16’ 20°6 correspondence Address: ROHM AND HAAS COMPANY PATENT DEPARTMENT (51) Publication Classi?cation Int. Cl. 0992 99/00 (2006.01) 100 INDEPENDENCE MALL WEST (52) us. Cl. .......................................... .. 252/1; 502/400 PHILADELPHIA, PA 19106-2399 57 ABSTRACT (21) Appl. No.: 11/705,483 ( ) (22) Feb. 12, 2007 A solid composition containing at least one borohydride compound and at least one base. Filed; Aug. 16,2007 US 2007/0187636 A1 BOROHYDRIDE FUEL FORMULATION [0001] This application claims the bene?t of priority under 35 U.S.C. §119(e) of US. Provisional Patent Application No. 60/774,253 ?led on Feb. 16, 2006. [0002] This invention relates to a solid borohydride-con taining formulation useful for hydrogen generation in fuel than 35% solids, alternatively no more than 30%. The Water may contain small amounts of additives, e.g., anti-foaming agents, surfactants, etc. [0009] The present invention is further directed to a method for improving How of poWdered metal borohydride salts, and to a solid composition having improved ?oW...
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...koncentrationen af citronsyre i de forskellige frugter. Til det bruger vi NaOH, (Natriumhydroxid). Ved syre-base titrering med NaOH spalter denne citronsyrens 3 hydroner. Forenklet reaktion: H3Cit (aq) + 3 OH- (aq) Cit3- (aq) + 3H2O (l) Ved denne her syre-base titrering afgiver H3Cit alle sine H+-ioner og bliver derfor til Cit3- og OHbliver til H2O. Dette kaldes for korresponderende syre-/basepar. (Tabel 9-2 166) Som man kan se her på Citronsyres titrerkurve, så ligger ækvivalenspunktet ca. mellem 8 og 9. Derfor vil vi benytte phenolphthalein som indikator, da den har et farveomslag fra 8 – 10, (Tabel 9-5 174) Stofmængde og Koncentration n=c*V stofmængde = koncentration * volumen For at finde koncentrationen af en vandigopløsning af syre er man nødt til at finde stofmængden af opløsningen med en kendt koncentration. Dette gøres ved at multiplicere koncentration med volumen. Da størrelsesforholdet mellem H3Cit og NaOH er 1:3. Skal man dividere stofmængden af NaOH med 3. Når man har stofmængden af opløsningen med den kendte koncentration divideret med 3, kan man finde koncentrationen af den anden vandige opløsning ved at omskrive stofmængdeformlen. n = c * V c = n / V Koncentration = stofmængde / volumen. Forsøgsopstilling og materialer Apparatur Måleglas, 10 ml Konisk kolbe, 100 ml Forsøgsstativ Buretteholder Burette Magnetomrører og magnet Kemikalier 0,100 M NaOH Phenolphthalein Appelsinsaft Citronsaft Fremgangsmåde Først pressede...
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...Acis CHEMICAL REACTIONS: ACID-BASE BUFFERS Short Overview Acids and bases represent two of the most common classes of compounds. Many studies have been done on these compounds, and their reactions are very important. Perhaps the most important reaction is the one in which an acid and base are combined, resulting in the formation of water (in aqueous solution) and a salt; this reaction is called neutralization. A buffer solution is a solution that contains both an acid and a salt containing the conjugate base anion in sufficient concentrations so as to maintain a relatively constant pH when either acid or base is added. In this experiment you will prepare a buffer solution and observe its behavior when mixed both with an acid and a base. You will also compare the behavior with that of solutions containing only the acid. Theory In his theory of ionization in the 1880’s, Svante Arrhenius defined acids are substances which form H+ and bases as substances which form OH- in water. He further defined a salt as a substance other than an acid or base which forms ions in aqueous solution. Such substances are thus capable of producing an electric current and are called electrolytes. The amount of electricity produced is directly proportional to the concentration of ions in solution. With regard to electrolytes we have learned previously that strong acids and strong bases ionize completely, and are therefore strong electrolytes because they...
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...hydroxide is prepared by weighing the sodium hydroxide, the concentration of the solution may not be precisely the intended concentration. Potassium hydrogen phthalate on the other hand, has a lesser tendency to absorb water from the air and when dried will remain dry for a reasonable period of time. Potassium hydrogen phthalate may be purchased in pure form at reasonable cost. Potassium hydrogen phthalate is a primary standard. This means that carefully prepared solutions of known concentration of potassium hydrogen phthalate may be used to determine, by titration, the concentration of another solution such as sodium hydroxide. The equation for the reaction of potassium hydrogen phthalate with sodium hydroxide is: KCO2C6H4CO2H + NaOH ( KCO2C6H4CO2Na + H2O The equivalence point of a titration occurs when chemically equivalent amounts of acid and base are present. At this point the pH changes rapidly with a small addition of acid or base. If a pH meter is used in the titration and the pH plotted vs the volume of base added, the equivalence point is the middle of the vertical part of the curve....
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...different between levels of CO2 (carbon dioxide) produced from a plant. In this experiment, we use Elodea because it is an aquatic plant. Although photosysthesis is done differently with different plants, this process always begins when energy from light is absorbed by proteins called reaction centers that contain the pigment chlorophyll green continent. In plants, these proteins are held inside organelles called chlorophasts, which is the largest of the quality of the leaf cells. The color of the emiited light on individual plants is depending by the photosynthetic rates of them. It have the ability to use water for photosynthesis, producing CO2, and gradually accumulating in the atmosphere. We put NaOH (sodium hydroxide) to help measure what is the carbonic acid levels. When NaOH (sodium hydroxide) is added to water with contain CO2 (carbon dioxide), the carbonate ions will form but excess of CO2 (carbon dioxide) into bicarnonate ions vaporized mixture of sodium carbonate, then NaHCO3 (sodium bicarbonate) will obstained. At the end of the...
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...lab, a calculation was done with the given variables of 60.0mL and 0.5000M for a NaOH solution. Looking for grams, the result of 1.20g was found. With this number, the lab activities were to be initiated. All lab participants in the group all retrieved and wore lab goggles that were adjusted and made proper for the lab. The proper apparatus was then collected from their appropriate cabinets and containers. As the lab was conducted during lunch, there was no competition between the choice of instruments and therefore the most sterile and in good condition were chosen. The method of collection is as follows, two graduated cylinders were gathered from cabinets from a lab member and the Erlenmeyer flask was acquired from another cabinet by another lab member. The buret itself was retrieved from another lab member while one person was...
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...EDDIKE Formål: Formålet med forsøget er, at bestemme indholdet af eddikesyre i husholdningseddike, ved at foretage en titrering med en NaOH-opløsning Apparatur: * En vægt * En målekolbe (250 mL) * En pipette med sugebold (25 mL) * Et stativ med muffe og klemme * En burette * En tragt * En konisk kolbe (250 mL) * En magnetomrører Kemikalier: * Husholdningseddike (5%) * 0,100 Μ NaOH * Phenolphthalein-opløsning Fremgangsmåde: Til at starte med skal man fremstille en fortyndet opløsning af eddike; En vægt nulstilles og massen af den tomme 250 mL målekolbe vejes. Herefter hælder man ved hjælp af pipetten 25,0 mL eddike i målekolben og massen af målekolbe og eddike vejes. Derefter fyldes målekolben op med demineraliseret vand til stregen, så man nu har præcis 250 mL opløsning. Til sidst sættes proppen på målekolben og indholdet rystes godt sammen. Til titreringen overføres 25,0 mL af den fortyndede eddike til en ren 250 mL konisk kolbe. 3 dråber af i Phenolphthalein-opløsning tilsættes eddikeopløsningen. Man kan nu starte titreringen med 0,100 Μ NaOH, der ved hjælp af buretten langsomt dryppes ned i den koniske kolbe. Så snart en enkel dråbe fra buretten bevirker at opløsningen bliver svagt rød stoppes titreringen og Volumen af det tilsatte 0,100 Μ NaOH aflæses. Titreringen gentages to gange for at få et mere præcist resultat. Teori: Husholdningseddike er en opløsning af eddikesyre i vand. Desuden...
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...hydroxide is prepared by weighing the sodium hydroxide, the concentration of the solution may not be precisely the intended concentration. Potassium hydrogen phthalate on the other hand, has a lesser tendency to absorb water from the air and when dried will remain dry for a reasonable period of time. Potassium hydrogen phthalate may be purchased in pure form at reasonable cost. Potassium hydrogen phthalate is a primary standard. This means that carefully prepared solutions of known concentration of potassium hydrogen phthalate may be used to determine, by titration, the concentration of another solution such as sodium hydroxide. The equation for the reaction of potassium hydrogen phthalate with sodium hydroxide is: KCO2C6H4CO2H + NaOH ( KCO2C6H4CO2Na + H2O The equivalence point of a titration occurs when chemically equivalent amounts of acid and base are present. At this point the pH changes rapidly with a small addition of acid or base. If a pH meter is used in the titration and the pH plotted vs the volume of base added, the equivalence point is the middle of the vertical part of the curve....
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...equilibrium forms in which aqueous acid molecules, HA(aq), react with liquid water to form aqueous hydronium ions and aqueous anions, A-(aq). The latter are produced when the acid molecules lose H+ ions to water. HA(aq) + H2O(l) H3O+(aq) + A-(aq) Water is not included in the acid-dissociation equilibrium expression because the [H2O] has no effect on the equilibrium. Acid + Base→ Salt+ Water Materials Used 10, 50 and 100-mL graduated cylinder 125-mL flask 3.5-mL of 6M NaOH Solution Distilled Water Glass stirring rod Beaker 50-mL of Unknown Acid Solution 25- or 50-mL buret Ringstand with buret clamp 10-mL pipet 125mL flask Phenolphthalein indicator Short range pH paper pH meter Procedure A. Determination of Ka for an Unknown Acid in Solution * Measure and deposit approximately 50-mL of unknown acid into a clean dry 100-mL beaker * Wash and rinse a 25- or 50-mL buret with 5-mL of the previously prepared NaOH solution * Fill buret with NaOH (previously prepared) solution and mount on ringstand * Wash and rinse a 10-mL pipet with the unknown acid solution * Into a clean 125-mL flask, pipet 10.00-mL of...
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... (2) a weak base and its salt with a strong acid. These are called Basic buffers. e.g.NH4OH + NH4Cl. Let us illustrate buffer action by taking example of a common buffer system consisting of solution of acetic acid and sodium acetate (CH3COOH/CH3COONa). CH3COOH --- H+ + CH3COO– CH3COONa ---- Na+ + CH3COO- since the salt is completely ionised, it provides the common ions CH3COO– in excess. The common ion effect suppresses the ionisation of acetic acid. This reduces the concentration of H+ ions which means that pH of the solution is raised. Thus, a 0.1 M acetic acid solution has a pH of 2.87 but a solution of 0.1 M acetic acid and 0.1 M sodium acetate has a pH of 4.74. Thus 4.74 is the pH of the buffer. On addition of 0.01 mole NaOH the pH changes from 4.74 to 4.83, while on the addition of 0.01 mole HCl the pH changes from 4.74 to 4.66. Obviously the buffer solution maintains fairly constant pH and the changes in pH could be described as marginal. Buffer Action: A...
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