...29 EXPERIMENT 3. ACID-BASE TITRATIONS: DETERMINATION OF CARBONATE BY TITRATION WITH HYDROCHLORIC ACID BACKGROUND Carbonate Equilibria In this experiment a solution of hydrochloric acid is prepared, standardized against pure sodium carbonate, and used to determine the percentage of carbonate in a sample. An aqueous solution of hydrochloric acid is almost completely dissociated into hydrated protons and chloride ions. Therefore, in a titration with hydrochloric acid the active titrant species is the hydrated proton. This species is often written H3O+, although the actual form in solution is more correctly (H2O)nH+. For convenience we designate it simply H+. Carbonate in aqueous solution acts as a base; that is, it is able to accept a proton to form bicarbonate ion. 2CO3 + H+ HCO3 (1) Bicarbonate is able to combine with another proton to form carbonic acid: HCO3 + H+ H2CO3 (2) Equilibrium expressions for the dissociation of bicarbonate and carbonic acid may be written 2[H+] [CO3 ] K2 = (3) [HCO3] [H+] [HCO3] [H2CO3] and K1 = (4) 30 where K1 and K2 are the first and second acid dissociation constants for H2CO3; the experimentally determined values are K1 = 3.5 x 10-7 and K2 = 5 x 10-11. When successive protonation reactions such as (1) and (2) occur, the extent to which the first reaction proceeds before the second begins depends on the difference between the two acid dissociation constants. By combination of Equations (3) and (4) with those for charge and...
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...CHEMISTRY: MATTER AND EQUILIBRIUM Indigestion and Titration: An Acid-Base Titration Imagine yourself as the Lead Analytical Chemist at Kaplan Industries. Your first big assignment is to investigate the strength of several commercial antacids for the Food and Drug Administration (FDA). They have sent five antacids to be tested with a back-titration that works as follows: • • • First, each antacid tablet is mixed with 40 mL of 0.1 M HCl—this acidic solution is the same stuff that is in stomach acid, and one antacid pill is nowhere near enough to neutralize all 40 mL of the acid. So, to see how much extra help each antacid pill needs to neutralize 40 mL of 0.1 M HCL, you add 0.05 M NaOH drop-by-drop to back-titrate the solution until the pH is neutral. What this means is that, the stronger the antacid tablet, the less NaOH it will take to help bring the acid to neutral. (In other words, the stronger antacid tablets counteract more of the original HCl, leaving the solution closer to neutral before the NaOH is added.) Here are your results: Maalox Mass of one dose antacid mL NaOH used in backtitration 20.0 g Tums 21.0 g Mylanta 18.0 g CVS brand 18.3 g Rennies 17.5 g 24.1 mL 22.4 mL 20.0 mL 19.9 mL 24.4 mL 1. Which is the strongest antacid, on a single-dose basis? Which is the weakest? Explain and show your calculations. 2. Which are the strongest and weakest, on a by-weight (mass) basis? 3. When people do back titrations, they usually watch the solution for a color...
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...Titlle: Evaluation of Gas Law Constant. Objective: To experimentally determine the value of the universal gas constant , R. Theory / Background : The ideal gas law equation is expressed as PV=nRT and is used in most problems dealing with changes situations involving gases. This law can be used to approximate the behaviour of various gases under many situations with a few limitations. The term PV = nRT is also called the compression factor and is a measure of the ideality of the gas. An ideal gas will always equal 1 when plugged into this equation. The greater it deviates from the number 1, the more it will behave like a real gas rather than an ideal. A few things should always be kept in mind when working with this equation are: * Pressure is directly proportional to number of molecule and temperature. (Since P is on the opposite side of the equation to n and T) * Pressure, however, is indirectly proportional to volume. (Since P is on the same side of the equation with V) In this experiment, we will be using this law to evaluate R, the gas law constant. If R is to be determined in this experiment, the other parameters of P, V, n and T must also be available in this experiment. From this experiment known amount of Magnesium used and the stoichimometry of reaction the number of moles of hydrogen can be calculated. Mg(s) + 2 HCl MgCl2 + H2 Hydrogen collected in the eudiometer tube. So, the gas pressure in the tube after the reaction ceased...
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...Title: To determine the coefficient of static friction between two surfaces Objective: To investigate the relationship between the mass of load and the length of spring and the coefficient of static friction between two surface. Part 1: The relationship between the mass of load and the length of spring Apparatus and materials: Retort stand, spring, Slotted masses 200g with hanger, Meter rule Setup: Procedure: 1. One of the end of the spring is hooked on the retort stand. 2. The hanger with a 20g slotted mass is hang at the other end of the spring. 3. The length l1 of the spring has been measured, mass m1 of the load are recorded. 4. The mass m1 is increase and corresponding length l1 of the spring has been measured. 5. Data of l1 and m1 is tabulated. 6. Graph of l1 against m1is plotted. Part 2: The coefficient of friction between two surfaces Apparatus and Materials: smooth plank as inclined plane, Retort stand, wooden blocks, Electronic balance, spring, Protractor, Pendulum bob, Thread, Plasticine. Setup: Theory: If the wooden block is being displaced down the inclined plane, the block will return to its original position when released because the net force up the plane exceeds the limiting friction down the plane. The downward displacement is being reduced gradually until a stage where the block stays stationary when released. At this point, the force up the plane equalized the limiting friction down the plane. If T is the...
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...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 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 ...
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...Amphoterism From Wikipedia, the free encyclopedia (Redirected from Ampholytes) Jump to: navigation, search "Amphoteric" redirects here. For other uses, see Amphoteric (disambiguation). Acids and bases | | * Acid dissociation constant * Acid-base extraction * Acid–base reaction * Acid–base titration * Dissociation constant * Acidity function * Buffer solutions * pH * Proton affinity * Amphoterism * Self-ionization of water * Acid strength | Acid types | * Brønsted · * Lewis · * Mineral · * Organic · * Strong · * Superacids · * Weak | Base types | * Brønsted · * Lewis · * Organic · * Strong · * Superbases · * Non-nucleophilic · * Weak | * v · * t · * e | In chemistry, an amphoteric species is a molecule or ion that can react as an acid as well as a base.[1] The word is derived from the Greek word amphoteroi (ἀμφότεροι) meaning "both". Many metals (such as zinc, tin, lead, aluminium, and beryllium) form amphoteric oxides or hydroxides. Amphoterism depends on the oxidation state of the oxide. One type of amphoteric species are amphiprotic molecules, which can either donate or accept a proton (H+). Examples include amino acids and proteins, which have amine and carboxylic acid groups, and self-ionizable compounds such as water and ammonia. Ampholytes are amphoteric molecules that contain both acidic and basic groups and will exist mostly as zwitterions in a certain range...
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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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...“Chemical Kinetcs – The hydrolysis of PNA Ester” Introduction: Reaction of a compound with water can result in a splitting, or lysis, of the compound into two parts. Organic molecules containing a group of atoms called an ester can be hydrolyzed by water to form a –COOH group (carboxylic acid) and an HO-- group (alcohol) as follows: RCOOR’ + H2O ( RCOOH + HOR’ This reaction is spontaneous for almost all esters but can be very slow under typical conditions of temperature and pressure. The reaction occurs at a much faster rate if there is a significant amount of base (OH-) in the solution. In this lab experiment, the rate of this reaction will be studied using an ester called para-nitrophenyl acetate (PNA), which produces an alcohol, para-nitrophenol (PNP). Question: What is the rate of reaction for the hydrolysis of PNA? What is the rate constant k? How are the rate of reaction and the rate constant k affected by varying (1) substrate PNA concentration, and (2) changes in pH (OH- base concentration) and addition of different nitrogen-containing base compounds (i.e.catalysts)? Hypothesis: I hypothesize that the rate of reaction and the rate constant for the hydrolysis of PNA can be determined experimentally to be first order. Also, in the reaction, the experiment will develop as follows: PNA +H2O --> PNP (yellow) + Ac Materials and Methods: The following solutions will be used in the experiment. 1. 0.2 M Phosphate Buffer, pH 6.5 (13.6 g KH2PO4 / 0.5 L, adjust...
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...och baser (Answers on page 18) Topic: Acid-Base Definitions 1. According to the Lewis definition, a base is a(n): A) Proton donor. B) Electron pair donor. C) Hydroxide ion donor. D) Hydrogen ion donor. E) Electron pair acceptor. 2. Which of the following is not both a Bronsted-Lowry acid and a Bronsted-Lowry base? A) HSO4! B) H2PO4! C) HCO3! D) OH! E) SH! 3. Which of the following is not a conjugate acid - conjugate base pair (in that order)? A) H3PO4, H2PO4! B) HBF4, BF4! C) CH3CH2OH, CH3CH2O! D) H3O+, H2O E) HPO4!, H2PO4! 4. The conjugate base of sulfuric acid is: A) H3SO4+ B) SO3 C) HSO4! D) H2SO3 E) HSO3! A) B) C) D) E) Topic: Acid-Base Definitions 6. Which of these is not a true statement? A) All Lewis bases are also Bronsted-Lowry bases. B) All Lewis acids contain hydrogen. C) All Bronsted-Lowry acids contain hydrogen. D) All Lewis acids are electron deficient. E) According to the Bronsted-Lowry theory, water is both an acid and a base. 7. For the equilibrium CH3NH3+ + H2O CH3NH3+ + H3O+ the two substances which both are acids are: A) H2O and H3O+ B) CH3NH3+ and H2O C) CH3NH3+ and CH3NH2 D) CH3NH3+ and H3O+ E) CH3NH2 and H2O 8. Which of the following is not a Lewis base? A) NH3 B) H! C) BF3 D) H2O E) H3C! 9. Which of the following is not a Bronsted-Lowry acid? A) H2O B) (CH3)3N C) NH4+ D) CH3CO2H E) HC"CH 5. Consider the equilibrium. Which are the Bronsted-Lowry bases? PO43- + H2O Chapter 3 HPO42- +...
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...Acid-Base Balance Kelly Heffron Grand Canyon University NUR-614 September 16, 2015 Acid-Base Balance The acid base balance is a homeostatic process that aides the body in maintaining a pH in the arterial blood between 7.35-7.45 (Patient, 2015). The body works together through multi-systems to ensure that acidity or alkalinity never take over within the blood. The purpose of the following paper is define the classification of the acid-base balance, define the factors from the case study, explain the pathophysiology, describe the compensatory mechanisms, pharmacological interventions, and the educational needs of patients with an imbalance. Classification In the following case study, the patient presents with metabolic alkalosis. Metabolic acidosis is a state within the blood when sodium bicarbonate (HCO3) increases. This condition can arise when the there is an acid loss within the body and HCO3 in the blood increases (Merk Manual, 2015). This process can cause the intracellular shifting of hydrogen ions, thus causing HCO3 retention. In the case study it is identified that the kidneys have a higher content of HCO3 because of the volume depletions. Normally, the kidneys filter out the HCO3 and excrete it into the urine (Merk Manual, 2015). In the case study, compensatory mechanisms have not activated, because the PaO2 is still within normal range of 35-45mm Hg, with a level of 40mm Hg. When excretion does not occur, the acid-base balance shifts from homeostasis...
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...THEORIES OF ACIDS AND BASESThis page describes the Arrhenius, Bronsted-Lowry, and Lewis theories of acids and bases, and explains the relationships between them. It also explains the concept of a conjugate pair - an acid and its conjugate base, or a base and its conjugate acid. | | | The Arrhenius Theory of acids and basesThe theory * Acids are substances which produce hydrogen ions in solution. * Bases are substances which produce hydroxide ions in solution.Neutralisation happens because hydrogen ions and hydroxide ions react to produce water.Limitations of the theoryHydrochloric acid is neutralised by both sodium hydroxide solution and ammonia solution. In both cases, you get a colourless solution which you can crystallise to get a white salt - either sodium chloride or ammonium chloride.These are clearly very similar reactions. The full equations are:In the sodium hydroxide case, hydrogen ions from the acid are reacting with hydroxide ions from the sodium hydroxide - in line with the Arrhenius theory.However, in the ammonia case, there don't appear to be any hydroxide ions!You can get around this by saying that the ammonia reacts with the water it is dissolved in to produce ammonium ions and hydroxide ions:This is a reversible reaction, and in a typical dilute ammonia solution, about 99% of the ammonia remains as ammonia molecules. Nevertheless, there are hydroxide ions there, and we can squeeze this into the Arrhenius theory.However, this same reaction also happens...
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...Acid-Base Imbalance Janet J Memoli Grand Canyon University NUR 641E September 30, 2015 Acid- Base Imbalance One of the basic concepts that new nurses need to learn is that homeostasis in the body is maintained by the acid base balance in the body. That concept is critical when looking at arterial blood gases. This can help guide the nurse to anticipate what the doctor will order and the education that she needs to give the patient and the family. This case study should help to illustrate the point. Case Study The case study that was given to us is a 22 year old woman who reports being “sick with the flu” She has been vomiting and having difficulty keeping food and drink down. In addition she has been taking antacids to calm down the nausea. After fainting at home she was driven to the local hospital where they have put in an IV. Her blood gas reveals the following: pH of 7.5, PaCO2 = 40 mm Hg, PaO2= 95 mm Hg, SaO2 = 97% and HCO3- = 32 meq/liter. Interpretation If you start with the basics on this case, the first thing to determine if it is an alkalosis or an acidosis. pH is 7.5 so the result is alkalosis. pH below the 7.35 is an acidosis and pH above the 7.45 is an alkalosis. There are two organ systems that primarily help with the acid base balance in the body and that is respiratory and renal. The renal system contributes to metabolic acidosis or alkalosis. When we look at the respiratory system we are looking at the PaCO2 which in...
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...ACID-BASE DISORDERS MADE SO EASY EVEN A CAVEMAN CAN DO IT Lorraine R Franzi, MS/HSM, RD, LDN, CNSD Nutrition Support Specialist University of Pittsburgh Medical Center Pittsburgh, PA I. LEARNING OBJECTIVES The clinician after participating in the roundtable will be able to: 1) Indicate whether the pH level indicates acidosis or alkalosis. 2) State whether the cause of the pH imbalance is respiratory or metabolic. 3) Identify if there is any compensation for the acid-base imbalance. II. INTRODUCTION Acid-Base balance is an intricate concept which requires an intimate and detailed knowledge of the body’s metabolic pathways used to eliminate the H+ ion. Clinicians may find it daunting to understand when first introduced to the subject. This roundtable session will demonstrate how to analyze blood gas levels in a very elementary manner so as to diagnose any acid-base disorder in a matter of minutes. The body is in a constant state of flux delicately stabilizing the pH so as to maintain its normalcy. In order to prevent untoward effects of alkalosis or acidosis the body has three major buffering systems that it uses to adjust the pH. They are: 1) Plasma protein (Prot-) 2) Plasma hemoglobin (Hb-) 3) Bicarbonate (HCO3-) The Bicarbonate-Carbonic acid system is the most dominate buffering system and controls the majority of the hydrogen ion (H+) equilibrium. Maintaining homeostasis when these acid-base shifts occur is vital to survival. Metabolic and respiratory...
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...emergency department for management of acute mushroom poisoning. Her respirations are slow and shallow, and she is non-responsive. She is admitted to the critical care unit to be closely monitored for the development of ventilatory failure and renal failure, which often accompany mushroom poisoning. Her urine output is decreased at about 20 ml/hr. Her laboratory values are: * Serum K+ = 5.7 mEq/L * Arterial blood gases (ABGs) * pH = 7.13 * PaCO2 = 56 mm Hg * PaO2 = 89 mm Hg * HCO3– = 18 mEq/L. Questions 1. What is the relationship between acid-base balance and serum potassium level? 2. What is the reason for L.S.’s low urine output? How should her fluids be managed? 3. Categorize and explain the probable cause of L.S.’s acid-base disorder. 4. Can L.S. compensate for her acid-base disorder? Why or why not? 5. How should her acid-base imbalance be medically managed? 1. Acid-base balance can influence the serum K+ levels detected in the blood. When a patient experiences hypokalemia, K+ is excreted from the cells and H+ takes its place creating an alkalotic state; K+ is processed out of the body via the kidneys and polyuria can be a clinical symptom. In the case of hyperkalemia, K+ is not properly processed by the kidneys as a result of renal failure; decreased urine output is a clinical symptom. 2. The reason for the patient’s low urine output is due to her acute renal failure. Since the kidneys are in failure, they cannot properly...
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...School of Nursing, Midwifery and Interprofessional Studies. With reference to acid-base balance explore the role of the respiratory system in maintaining blood pH? ‘We live and die at the cellular level’ (Reid, 2011). Homeostasis is crucial for normal cellular function. Acid-base homeostasis is the part of human homeostasis and refers to the balance between the production and elimination of H+ hydrogen ions (pH) within the body fluids (William, Simpkins, 2001, p.236). Metabolic reactions within the cells often produce a huge excess of H+. Lack of any mechanism for its excretion would lead H+ levels in body fluids rise quickly to the lethal levels (Tortora, Grabowski 2006, p.1001); therefore the homeostasis of the right H+ levels is crucial for our survival. In a healthy person several systems work interdependently on maintaining blood’s pH (Sheldon, 2001, p.23): buffer, renal and respiratory systems. In this essay I will concentrate on the pH of the blood in relation to the acid-base balance and the role that respiratory system has in maintaining it. Blood pH is a measure of its acidity or alkalinity. A pH of 7.4 is considered neutral in the systemic arterial blood within its narrow range of around 7.35 and 7.45. When the pH is greater than 7.45 the blood is considered to be alkalotic and when the pH is lower than 7.35 then the blood is considered acidotic (Sheldon, 2001, p.23). Fig. 1: Diagram of blood pH scale: (JupiterIonizer, 2004) The acidity or alkalinity...
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