...Onion Extract as pH/ Acid-Base Indicator _______________ A Science Investigatory Project Presented to Mrs. Shellah Marie Tabayoyong-Cruz Marist School, Marikina City _______________ In Partial Fulfillment of the Requirements for the Course Science & Technology 9 _______________ Presented by TAGAÑA, Kurt Lance C. CORDOVA, Chedric Joshua L. CONCEPCION, Ludwig Michael T. 9-St. Titus March 2014 ACKNOWLEDGEMENT The researchers of this study would like to thank Mrs. Gay Fan for sharing her advices and ideas about chemistry. Truly, without her help, this study wouldn’t be made. They would also want to acknowledge the help of Mrs. Aurora Ramos by letting them borrow a pH wheel with pH papers in it. Last, but not the least, they would want to thank Mrs. Shellah Marie Cruz for her efforts in checking, criticizing, and helping the researchers for the good of their study. TABLE OF CONTENTS Abstract 3 Chapter I: Introduction 4 Chapter II: Review of Related Literature 7 Chapter III: Methodology 9 Chapter IV: Presentation, Analysis and Interpretation 11 Chapter V: Generalization 12 Chapter VI: Recommendation 13 Bibliography 14 ABSTRACT The study aims to provide chemists a source of an accurate acid-base/ pH indicator which is abundant and can be found anywhere in order to help them in certain laboratory situations such as identifying whether a solution is an acid or base. Red onion extract...
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...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 a base is that weight which reacts...
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...change in its pH an addition of strong acid or alkali. Types 1 Mixture of weak acids with their salt with strong base i.e. (weak acid + salt of weak acid , conjugated base) 2 Mixture of weak bases with their salt with strong acid i.e. (weak base + salt of weak acid , conjugated acid) Examples: H2CO3/NaHCO3(Bicarbonate buffer) (Carbonic acid and Sodium Carbonate) CH3COOH/CH3COONa(Acetate buffer) (Acitic acid and Sodium acetate) Na2HPO4/NaH2PO4(phosphate buffer) Buffer capacity: Buffering capacity is the no. of grams of strong acids or alkali which is necessary for a change in pH of one unit of one lit. of buffer solution. Axn: When HCl or NaOH is added to acetate buffer * CH3COONa + HCl→CH3COOH + NaCl * CH3COOH + NaOH→CH3COONa + H2O Thus change in pH is minimized BUFFER OF THE BODY FLUIDS Cellular metabolism predominantly yields acids so it is approcipriate that body buffer has buffering capacity to absorb acids are first line of defense against acid load. a Bicarbonate buffer system ( H2CO3/NaHCO3) % of buffering capacity, Plasma- 65% Whole body- 40% CO2 and H2CO3 can freely diffuse across the cell membrane and vascular capillary epithelium. Regulation, Base constituents-kidney (metabolic component) Acid constituents –respiration (Respiratory) Salt / Acid – 20 b. Phosphate buffer system (Na2HPO4/NaH2PO4) Primary intracellular buffer, its concentration in plasma is vary low Salt /Acid-4 c. Protein buffer systems ...
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...Not So Accurate Indicator for pH Tammy Daniel BIOL2101 9/28/12 Ms. Hunter INTRODUCTION The pH scale is based on the number of hydrogen ions in a solution. The actual concentration of hydrogen ions, [H+], and hydroxyl ions [OH] in moles per liter are indicated for each pH value noted. Acidity and alkalinity can be demonstrated on the pH scale, which ranges from zero to fourteen. Anything less than seven is acidic and anything greater than seven is basic. Seven is neutral with an even concentration of H+ and HO- ions. The farther from the center of the scale a substance is the stronger of an acid or base it is. For example an acid with a pH of one or two is a very strong acid, while a six is a weak acid. As well, a base of thirteen or fourteen is a very much stronger base than that of a pH of eight. The measurements on the pH scale are logarithmic, with each unit representing tenfold change in H+ ion concentration. The idea of the pH scale was devised by a Danish biochemist and part-time beer brewer named Soren Sorensen in 1909. He was searching for a convenient means of checking the acidity of his alcoholic product to prevent its spoilage by bacterial action. (Human Anatomy and Physiology; Seventh Edition ) Acids are proton donors while bases are proton acceptors. Referring to the pH scale numbers zero to fourteen, stomach acid and lemon juice are examples of strong acids having a pH of one and two while ammonia is an example of a base having a pH of 12...
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...Outcome I Acids and Bases Define acid and base using Arrhenius, Bronsted-Lowry, and Lewis definitions. Classify common items as acid or base by their characteristics such as taste, reaction with indicators, etc. Calculate the pH and pOH of solutions and use pH to classify them as acids or bases Perform titration calculations using pH, pOH and molarities Definitions: Acid Base Arrhenius model Brønsted-Lowry model Conjugate Acid Conjugate Base Conjugate acid-base pair Amphoteric Lewis model Hydronium Strong acid Stron base Weak acid Weak base Ion product constant for water pH pOH Logarithm Neutralization reaction Salt Titrant Equivalence point End point Titration Indicator Questions and Calculations 1) a.What is Kw? b. What is the concentration of H3O+ in pure water? c. What is the concentration of OH- in pure water? d. What are the properties of a neutral solution? 2) Identify each of these as an acid, a base, both or neither | |Acid |Base |Both |Neither | |Fe | | | | X | |NaOH | | | | | |H2SO4 | ...
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...Background: Acids are substances that are characterized by their ability to donate protons (H+) to other substances in a solution. Acids can be strong or weak. Weak acids do not ionize completely and are found in everyday substances. Acidity is a measure of the amount of dissolved hydrogen ions in a solution. The greater the number of hydrogen ions in a solution, the more acidic the solution. Strong acids donate hydrogen ions in water, to a much greater extent than weak acids. Bases are substances that are characterized by their ability to accept protons or produce hydroxide ions (OH-) in an aqueous solution. As for acids, the difference in strength of bases directly relates to the degree in which hydroxide ions are formed by the base in water. Like strong acids, strong bases are also dangerous chemicals. Weak bases are found in many everyday items. When feeling the consistency of a base, it feels slippery because it degrades the fatty acids and oils in the skin on contact. However, due to the possibility that an acid or a base could be very dangerous to human tissue, never experiment with an acid or base by tasting or touching it. To determine if a substance is an acid or a base, a pH scale may be used. pH is a measure of the concentration of hydrogen ions in a substance. The equation for pH is: pH = -log [H+]. The logarithm for pH is based on a scale of 10. As pH is a negative logarithm, the pH of a substance increases as the concentration of hydrogen ions decreases. For...
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...Chemistry Acids and Bases I. Acids A. Definition Covalent molecular compound Ionizes in water Forms H+(aq) as the only cation B. Common acids Dil./ conc. HCl Very dil. HNO3 Dil. H2SO4 C. Basicity Number of H+(aq) produced per acid molecule Monobasic HCl, HNO3, CH3COOH Dibasic H2SO4, H2SO3 Tribasic H3PO4 Stepwise ionization for polybasic acids H2SO4 (aq) H+(aq) + HSO4-(aq) HSO4-(aq) H+(aq) + SO42-(aq) D. Physical properties Exist in all three states in pure form Solid (citric acid) Liquid (sulphuric acid H2SO4, carbonic acid H2CO3) Gas (hydrogen chloride HCl) Electrical conductivity Electrical conductor Electrolytes Conduct electricity in aqueous/ molten states Chemically decomposed upon conduction of electricity Mobile ions present: H+(aq) and other anions Conductivity of dibasic acid > monobasic acid More H+(aq) produced by dibasic acid of the same molarity Action on damp blue litmus paper Bluered Action on universal indicator/ damp pH paper Greenred/ turns red 1 © 2013 Victor Fong Chemistry Acids and Bases E. Chemical properties Species responsible for acidic properties: H+(aq) Reaction with metals Acid + metal salt + hydrogen Mg + 2HCl MgCl2 + H2 Only reacts with metals above Cu in MRS/ ECS Observations Metal dissolves to form a colourless/ coloured solution Colourless...
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...studyguide.pk Acids, Bases and Salts THE THEORY of ACIDS and ALKALIS and a few technical terms: o Acids are substances that form hydrogen ions (H+(aq)) when dissolved in water eg hydrochloric acid HCl gives H+(aq) and Cl-(aq) ions, sulphuric acid H2SO4 gives 2H+(aq) and SO42- ions and nitric acid HNO3 gives H+(aq) and NO3-(aq) ions. o Alkalis are substances that form hydroxide ions (OH-(aq)) in water eg sodium hydroxide NaOH gives Na+(aq) and OH-(aq) ions, calcium hydroxide Ca(OH)2 gives Ca2+(aq) and 2OH-(aq) ions. Note: an alkali is a base soluble in water. o In water, there are trace quantities of H+ and OH- ions BUT they are of equal concentration and so water is neutral. o In acid solutions there are more H+ ions than OH- ions. o In alkaline solution there are more OH- ions than H+ ions. o Acids dissociate to different extents in aqueous solution. Acids that dissociate to a large extent are strong electrolytes and strong acids. In contrast, acids that dissociate only to a small extent are weak acids and weak electrolytes In a similar manner, bases can be strong or weak depending on the extent to which they dissociate and produce OH– ions in solution. Most metal hydroxides are strong electrolytes and strong bases. Ammonia, NH3, is a weak electrolyte and weak base. o BASES eg oxides and hydroxides are substances that react and neutralise acids to form salts and water. Bases which are soluble in water are called alkalis. Acids Some common acids are listed below:...
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...Jonte Berry LAB 3 REPORT SHEET – ACIDS, BASES, INDICATORS, pH Procedure Number 3 Estimated pH with pH paper Vinegar (Ph 2) Soap + H2O (Ph 6) Tap water (Ph 8) Baking soda + H2O (Ph 9) Ammonia (Ph 13) 4 What color is your “red cabbage solution” when diluted with tap water? (The water turns ruby red) Do you think we will all have exactly the same color? Explain your answer. (No) 5 Solution color Estimated pH with cabbage indicator with cabbage indicator Vinegar (Light pink) (Ph 4) Soap + H2O (Clear Pink) (Ph 4) Tap water (Light blue) (Ph 10) Baking soda+H2O (Light light blue) (Ph 10) Ammonia (Clear) (Ph 10) 6 Describe what happened to the color of the solution when you mixed the vinegar and ammonia solutions. What do you estimate the pH of the solution to be with pH paper? (The pink color from the vinegar changes to light blue when the ammonia was added.) What do you estimate the pH of the solution to be with the cabbage indicator? (Ph 10) 7 What happened when you added the baking soda solution to the mixture of vinegar/ammonia? Describe your observations. (When I added the baking soda solution nothing happen at all.) What do you estimate the pH of the solution to...
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...5 Titration of a Strong Acid with a Strong Base Part I: The purpose of this experiment was to prepare an aqueous solution of NaOH, and to determine the concentration of the secondary standard NaOH solution by titrating it with a solute of primary standard, KHP. Another objective of this experiment was to learn how to plot a 2nd derivative graph using LoggerPro, and determining the concentration of the secondary standard from the 2nd derivative data. The primary standard was KHP and the secondary standard was NaOH. The difference between the 2 types of standards is that the primary standard is a has powerful reactants and isn't sensitive to the the environment and the secondary standard is something that is determined will react with a highly pure primary standard that can be standardized. It was necessary to standardize the NaOH solution because NaOH absorbs moisture from the air, making the compound not 100% NaOH, so to obtain precise concentrations, the NaOH needed to be standardized with KHP. The molarity of the NaOH solution was determined by dividing the average number of moles of NaOH (determined by taking the moles of KHP and using the 1:1 ratio) and diving it by the average volume (number of L) at the indicator point. The difference between the equivalence point and the indicator point is that the indicator point is where the indicator changes color, and the equivalent point is the place in a titration where the amount of indicator added neutralizes the solution...
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...prepared and the pH of the buffer and samples were determined through different liquid indicators and the pH meter. Also, the buffer capacity of the prepared buffer solution was calculated. The group was tasked to prepare a 250 mL phosphate buffer solution of pH 8.0 using dihydrogen phosphate ion (H2PO4) and primary sodium phosphate monohydrate (NaH2PO4.H2O). With the aid of 6.0 M HCl and 6.0 M NaOH, the pH of the buffer was adjusted while being recorded by the pH meter until it reached the desired pH. Afterwards, the buffer solution was introduced to Colorimetric Determination which used acid-base indicators. The buffer solution changed to color yellow when Thymol and Methyl red were added, blue when Bromophenol blue and Bromocresol green were included, purple for Bromocresol purple, pink for Phenol red and Phenolphthalein, and orange for Methyl orange. Introduction The measurement of the low concentration of hydrogen ions present in any biological process is expressed as pH. pH is used to measure the acidity and alkalinity of a solution. pH involves ionic activity, making it difficult to accurately predict the pH value of a solution. The pH is also known to greatly affect our biological system and any large changes could be dangerous, which is why there is a buffer present within our systems. The buffer solution is composed of an equal concentration of a weak acid and its strong conjugate base which, together, is capable of resisting any sudden changes in the pH due to its...
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...Acids and Bases Acids: Properties: Sour taste Change color of acid-base indicators Release hydrogen gas React with bases to produce salt and water Types: Binary acid: only two elements; hydrogen and another one (HF, HCl) Oxyacid: Hydrogen, oxygen, and a third element (HNO3, HClO) -Sulfuric Acid: dehydration, burning -Nitric Acid: Very volatile, used to make plastics -Phosphoric Acid: fertilizers -Hydrochloric Acid: digestion -Acetic Acid: synthesize chemicals. Bases: Properties: Bitter taste Change color in acid-base indicators Slippery Also produce salt and water Arrhenius Acids and Bases Acid: increases concentration of H+ ions (protons) Base increases concentration of hydroxide ions (OH-) Strength Strong acids: ionizes completely in aqueous solution Strong polarity Strong Bases: same as acids Alkaline: when a base dissociates to yield aqueous OH- ions Theories Bronsted Lowry: acid: proton donor Base: proton acceptor Reaction: protons are transferred to reach neutralization Monoprotic acid: can donate one proton per molecule Polypotric acid: can donate more than one proton per molecule Dipotric: can donate two per molecule Triprotic: three per molecule Lewis acid and bases Lewis acid: molecule that accepts an electron pair to form covalent bond Lewis base: molecule that donates electron pair Reactions Terms: Conjugate: what remains AFTER the reaction occurs The stronger the acid/base is, the weaker the conjugate...
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...Andreas Sippl Student ID: 4445491 Date: 04 January 4, 2015 Course and Section Number: SCIN131 Lesson 6 Lab: Titrations and Natural Acid/Base Indicators Begin by viewing the following Thinkwell videos 15.1.7 CIA Demonstration: Titrations 11.2.2 CIA Demonstration: Natural Acid-Base Indicators (NOTE: The second video is sort of a supplement to the first, and shows how this applies to your daily life. Feel free to try some of the things listed in the video, but be sure to report back to the class regarding the results of your experiments!) After you watch the above video, answer the questions below in sufficient detail: (a) (1 pts.) In YOUR OWN WORDS, what is a titration? What type of reaction is it? Be detailed and specific...
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...enquiries@educationscotland.gov.uk. This document is also available from our website at www.educationscotland.gov.uk. Contents Introduction 5 Chemical analysis 6 Qualitative and quantitative analysis 6 Volumetric analysis 6 Gravimetric analysis 14 Colorimetric analysis 17 Organic techniques 22 Introduction 22 Preparation 22 Isolation 24 Purification 29 Identification 33 Percentage yield 37 Errors 39 Accuracy and precision 39 Repeatability and reproducibility 41 Quantifying errors 41 Absolute uncertainties and percentage uncertainties 42 Combining uncertainties 43 Some ‘forgotten’ uncertainties 46 Experiments 53 Experiment 1A: Preparation of a standard solution of 0.1 mol l–1 oxalic acid 53 Experiment 1B: Standardisation...
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...of acetic acid in vinegar. Vinegar is a solution of acetic acid, an organic acid of formula CH3COOH (MW = 60.0526 g/mole). In order to be sold as vinegar, it needs to meet the FDA’s guideline of 5.00% acetic acid by mass. Knowing that the density of vinegar is 1.04 g/mL and analyzing this solution by titration, chemists can determine the mass percentage of acetic acid in a sample of vinegar. The titration reaction is given below: CH3COOH + NaOH ( CH3COONa + H2O Reaction 1 A customer has purchased a vinegar solution at a local thrift store at a 20% discount and he believes that the sample of vinegar he has purchased does not meet FDA regulations. He is suing the thrift store for the $0.36 he feels that he has been cheated out of. The court has asked you to analyze the sample and render your verdict. Does this sample conform to the FDA guideline? If 2.00 mL of the thrift store vinegar required 9.73 mL of 0.150 M NaOH to reach the endpoint, then 0.00877 g of acetic acid was present. 9.73 mL NaOH x 1 liter NaOH x 0.150 mole NaOH x 1 mole CH3COOH x 60.0526 g CH3COOH 1000 mL 1 liter 1 moles NaOH 1 mole CH3COOH = 0.0876 grams CH3COOH in sample 2.00 mL vinegar x 1.04 g vinegar = 2.08 g vinegar 1 mL 0.0876 g CH3COOH x 100 = 4.21 % CH3COOH by mass 2.08 g vinegar sample You can find the molarity of acetic acid in vinegar by dividing the number of moles of acetic acid in vinegar...
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