...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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...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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... AA Acids, Bases & Indicators Comprehensive tutorial notes Julius G.Thungu jgthungu@gmail.com 0711 354 885 INTRODUCTION TO ACIDS, BASES AND INDICATORS 1.In a school laboratory: (i)An acid may be defined as a substance that turn litmus red. (ii)A base may be defined as a substance that turn litmus blue. Litmus is a lichen found mainly in West Africa. It changes its colour depending on whether the solution it is in, is basic/alkaline or acidic. It is thus able to identify/show whether another substance is an acid, base or neutral. (iii)An indicator is a substance that shows whether another substance is a base/alkaline,acid or neutral. 2.Common naturally occurring acids include: Name of acid | Occurrence | 1.Citric acid | Found in ripe citrus fruits like passion fruit/oranges/lemon | 2.Tartaric acid | Found in grapes/baking powder/health salts | 3.Lactic acid | Found in sour milk | 4.Ethanoic acid | Found in vinegar | 5.Methanoic acid | Present in ants, bees stings | 6.Carbonic acid | Used in preservation of fizzy drinks like coke, Lemonade, Fanta | 7.Butanoic acid | Present in cheese | 8.Tannic acid | Present in tea | 3.Most commonly used acids found in a school laboratory are not naturally occurring. They are manufactured. They are called mineral acids. Common mineral acids include: Name of mineral acid | Common use | Hydrochloric acid (HCl)...
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...Alkali metals Cations occur in wide variety of important chemicals The metals are all very reactive when pure – strongly reducing Their cations (with the exception of lithium) have low charge densities – often leads to good solubility and an ability to stabilize anions that can not be formed along with any other cation Alkali metal physical properties Element Li Na K Rb Cs Density (gcm-3) 0.53 0.97 0.86 1.53 1.87 Melting point (oC) 180 98 64 39 29 ∆Hatm (kJmol-1) 162 108 90 82 78 1 Reactivity towards Bronsted acids The alkali metals react even with weak Bronsted acids such as water – The rate of reaction depends upon the acidity of the medium 2Na + 2H2O 2Na + 2EtOH 2Na + 2NH3 2NaOH + H2 2NaOEt + H2 2NaNH2 + H2 – very slow reaction in absence of catalyst Alkali metals and liquid NH3 Alkali metals react very slowly with liquid ammonia – however, they typically dissolve rapidly in ammonia to form highly colored solutions Na(s) --(ammonia)--> Na(am) + e-(am) – fast 2e-(am) + 2NH3 2NH2- + H2 – slow in absence of catalyst 2 Sodide anions and electrides 2Na(s) + C12H24O6 [Na(C12H24O6)]+Na– complexing or chelating agent is used to stabilize the cation » Na- is the sodide anion. It is the most stable alkalide ion Other complexing agents have been used to form solid salts where e- is the anion – electrides Lithium Lithium is the most reducing of all the alkali metals – but not the most reactive Unlike the other alkali metals it reacts with nitrogen to form a nitride Used...
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...(NH4NO3), Potassium Nitrate (KNO3) * Industrial: Modifying properties of cement mixtures, paint formulations, fillers in plastics, inks, medical industry * aHarvesHh ccscHarvesting sea salts, via evaporation, we know it’s a salt cos when you remove the metal and add h , you getan acid * the saltsttttttTHe salts are formed when the H of an acid is replaced by a metal * NaOH + H2So4 -->2NaOH + H2SO4 Na2SO4 + 2H2O * Oxides OosdoidikcxzjOxides and hydroxides are not salts * SoCcCCCCos when you replace the Metal with H, you get H2O =/= Acid * However, water can be considered an acid, sometimes * Nitrates | * All soluble | * Sulfates | * All soluble except clb (calcium lead barium) | * | * Mnemonics: Chinese language b | * Chloride | * All soluble except lms (lead, mercury, silver | * | * Learning management system, | * Carbonate | * All insouluble except spa (sodium, potassium, ammonium) | * | * Science practical assessment | * Precipitation: Prepare insoluble salt: 2 aqueous solutions combine to fom an insoluble solution * Method 2: Excess method. If acid +MCB(insol), use excesss * Method 3: Titration, Acid + MCB(sol), use titration * HNO3 + NaOH= NaNO3. Since Na2CO3 is soluble, use titration * Why use Naoh instead of Na2Co3, bcos, after reaction na2co3 liberates co2, which increases acidity of solution. innacurate * How to determine method...
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...chlorite hypochlorite periodate iodate hypoiodite bromate hypobromite hydrogen carbonate (bicarbonate) hydrogen sulfate (bisulfate) hydrogen sulfite (bisulfite) hydrogen oxalate (bioxalate) hydrogen phosphate dihydrogen phosphate Acid Formula Acid hydrogen sulfide Name borate HNO3 Nitric Acid tetraborate HNO2 Nitrous Acid hexafluorosilicate (not really an acid) HOH Water HCN Hydrocyanic Acid SCNThiocyanate HSCN Thiocyanic Acid C2HClO2-acetate (an write ) Perchlorate* alternate way to HClO4 acetate is CH3COOPerchloric Acid 3O 4 ClO3 Chlorate* HClO3 Chloric Acid ClO2 Chlorite* HClO2 Chlorous Acid There are only two positive polyatomic ions: ClOHypochlorite* HClO Hypochlorous Acid + H O2 C2is3calledI the ammonium ion and Acetate HC2 H3 O2 Acetic Acid NH4Chemistry MnO4 Permanganate HMnO4 Permanganic Acid 2+ Hg2 Polyatomic Ions mercury(I) ion is called the SO4 2Sulfate* H2 SO4 Sulfuric Acid 2Sulfite* Sulfurous Acid ! acids:Ion SO3 - a list of common polyatomic ions and acids: H2 SO3 tomic ions and Here’s Tests HSOFormula Hydrogen sulfate or H2 SOFormula Sulfuric Acid 4 Acid 4 Acid Name Ion Name Acid Acid Name September 23, 2005: Positive Ion Test: All of the monatomic ions and these polyatomic ions: + ! Bisulfate* um* NH4 2Ammonium* ammonium and mercury(I) Nitric Acid S2...
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...CHEMISTRY REVISION KINETIC THEORY 3 States of matter: Solid, Liquid, Gas Solubility of a solute in water, at a given temperature is the maximum amount of it that will dissolve in 100g of water at that temperature. Solubility = solution divided by solvent ATOMIC STRUCTURE: Plum Pudding- Thompson Thomson’s "Plum Pudding Model" each atom was a sphere filled with a positively charged fluid Rutherford-Proton predicted Neutron Chadwick-Neutron (No Charge hard to find) Mass proton and electron-1 Neutron-0 Mass number- Protons and Neutrons Atomic Number-Protons OR Electrons Isotope-A molecule with more than one type of atom Element-A substance which contains one type of atom Electronic configuration: 2,8,8,8,8,8 Ionic Bonding: Ionic bonding is between a metal and non metal. Metal gives up its electrons and becomes positively charged. Ionic bonding is caused by attraction. Ionic Compound Properties; High Melting and Boling Points require lots of energy to break apart. Conduct electricity when in molten. Covalent Bonding: Atoms share electrons. Simple molecular covalent compounds: Low Melting and Boling points. Strong in atoms. Weak in electrons. Easy to break apart. Cannot conduct electricity. Giant Molecular Covalent Compounds; Diamond-Very Hard. Very high melting and boiling points. Cannot Conduct Electricity. Graphite-Soft. High Melting and Boiling Points. Conducts Electricity. Metallic Bonding: A ladus of ions in a sea of electrons...
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...purity and high oil yield refined cottonseed oil. Available with both physical and chemical refinery technology, we are able to provide customers the most affordable cottonseed oil refining machines including design, manufacturing, installation with guaranteed quality and reliable service. Main Refining Process of Cottonseed Oil Refining Machine: (1).P-acid degumming operation of Cottonseed Oil Refining Machine Drawing the filtered or settled crude oil into the neutral pot, control oil te- mperature 40 ° C, liquid level cover the neutral pot volume about 80 %.Add into the neutral pot P-acid with 85% concentration, 0.1-0.2% oil weight.Start up neutral pot, make main shalf stirring at 60-70 r/min, finish de-gumming in 30 min. (2)alkali de-acid operation of cotton Cottonseed Oil Refining Machine After finish de-gumming process, at once add into lye carrying alkali refini- ng de-acid, lye concentration 16 ° Be ′, super alkali is 0.1-0.3% oil weight, afterfinish adding, continuous stirring 30min, when soap particles accumulated condensing, should reduce stirring speed, 30r/min avoid emulsion. After adding alkali, gradually rising temp to the end temp 65 ° C, see to th- at the rising temp speed should control at 1 degree per minute, not too fast. Shut off neutral pot drive part, the oil settled in the pot 6-8 hours, make oil separate from soap. (3)Water rinse operation of cottonseed oil refining machine Adjust the neutral pot oil temp to about 85 ° C, add into...
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...The chemistry of perming & rebonding Some of us have naturally curly hair but want it straightened; others have it naturally straight but want it curly. But whatever the style you like to wear, there's chemistry involved in it! The structure of hair Hair is made mostly of a protein called keratin, which is also present in nails. In hair, keratin molecules are arranged in straight bundles. These bundles are held together by disulphide bonds (-S-S-), which give strength to the hair. Disulphide bonds are made by the amino acid called cysteine. The cysteine of one keratin molecule forms a disulphide bond with the cysteine of the neighbouring keratin molecule. The more disulphide bonds there are in a strand of hair, the straighter it is. Ammonium thioglycolate: the perm salt Ammonium thioglycolate (HSCH2CO2NH4) is a compound that can break disulphide bonds. This is because it contains a thiol group (-SH). The thiol group replaces one of the sulphur atoms in the disulphide bond, like this: Keratin-S-S-keratin + 2HS-CH2CO2NH4 --> -HO2CH2CS-SCH2CO2H + 2NH3 + 2HS-keratin When the disulphide bond is broken, the keratin bundles come apart, and hair is weakened. Ammonium thioglycolate is therefore used widely in beauty parlours when customers want their hair re-styled. However, if you use too much of it, or if the reaction is left for too long, you could end up going bald. So do not, ever, try it at home! If you have watched the film Legally Blonde, you'll have seen Reese Witherspoon (acting...
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...area than with water alone. Disadvantages: 1. When used in hard water, soap can produce a scum - calcium and magnesium salts present in hard water react with the soap to cause this to happen. Soapless or synthetic detergents do not leave a residual film behind. 2. Considerable rinsing is required to remove soap scum. 3. Soap may produce a greasy build-up on the surface which can be slippery. 4. More expensive than synthetic detergents. Sample Products: 1. "Joy", "Ivory" (Procter & Gamble Co.) ANIONIC DETERGENTS Uses: 1. Commonly known as a "neutral" detergent. 2. The most widely used soapless detergent. 3. Available in both liquid or powder. 4. Manufactured from strong alkalis and weak acids. 5. Effectiveness is even greater when combined with a non-ionic detergent. 6. These detergents produce foam when used in excess quantities and, therefore, should only be used in the recommended amounts. Advantages: 1. Safe for...
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...strong acid and strong base and for a weak acid and a strong base Group size: Individual Introduction In thermometric titration we make use of the fact that reactions in solution are accompanied by temperature changes. For example, the neutralization reaction of hydrochloric acid and sodium hydroxide is an exothermic reaction. NaOH(aq) +HCl(aq) NaCl(aq) + H2O Hneut: negative The purpose of this experiment is to determine the concentration of two acids, hydrochloric acid, HCl, and ethanoic acid, CH3COOH in turn with a standardized solution of sodium hydroxide and record the temperatures of the mixtures during the course of the titration. In each case a plot of temperature against time will enable you to determine the maximum temperature rise, from which you calculate both the concentration of the acid and the enthalpy change of neutralization. --------------------------------------------------------------------------------------------------------------------------- Theory: Give principle/reason to explain how do you determine the concentration of hydrochloric acid and ethanoic acid by titrating with standardized sodium hydroxide and thermometric measurement is used. The following questions should be useful to you. 1. Define the term 'standard molar enthalpy of neutralization'. 2. Give an ionic equation for neutralization reactions. 3. Define the terms 'strong acid' and 'weak acid'. 4. The enthalpy change of neutralization for a very dilute strong acid reacting...
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...Atoms, Molecules and Ions. AN ATOM is the smallest particle of an element. They cannot be split into smaller particles in chemical reactions. Iron is made of iron atoms (Fe). Sulphur is made of sulphur atoms (S) A MOLECULE is a small group of atoms joined together. The atoms may be the same (e.g. O2) or different (e.g. H2O). The chemical formula shows the number and type of atoms present. Non-metal compounds are made of molecules: Carbon dioxide contains CO2 molecules Methane (natural gas) contains CH4 molecules AN ION is an atom or group of atoms with an electrical charge (+ or -). Metal compounds such as sodium chloride or copper sulphate contain ions. Sodium chloride is made of Na+ and Cl- ions Copper Sulphate is made of Cu2+ and SO42- ions Note that metals form positive ions while non-metals form negative ions. A solid is represented by (s). e.g. H2O(s) is ice. A liquid is represented by (l) e.g. Fe(l) is molten iron. A gas is represented by (g) e.g. H2O(g) is steam. A solution in water is represented by (aq). Salt dissolved in water is NaCl(aq). You should remember that the common gases are diatomic (have 2 atoms in each molecule). These are Oxygen O2; Hydrogen H2; Nitrogen N2; and Chlorine Cl2. Elementary Particles Atoms are made up of smaller particles called protons, neutrons and electrons. The protons and neutrons cluster together in a small nucleus at the centre of the atom while the electrons orbit the nucleus. The main properties...
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...Edible Oil Refining Machine Main Parts: (1) Refining section: used to P-acid de-gumming, alkali refining de-acid and water rinsing. (2) Decoloring section: used to remove off pigments, bleaching oils and grease dehydrate. (3) Deodorizing section: to remove off the odor components in oil. (4) Dewax: used to remove off the wax in the oil, in order to get the high quality oil. (5) Heat-transfer oil stove: supply each device production needing heat energy, temperature reach above 280°C. (6) Steam generator: produce the needing steam for de-odoring and distillation. (7) Vacuum pump: supply needing vacuum for dehydrate, de-color, de-odor. Vacuum degree can reach above 755mm Hg. (8) Press filter: filter clay, filter out clear oil. (9) Air compressor: blow dry bleached clay, blow empty the leftover oil in the press filter. Edible Oil Refining Machine Working Process: (1)Pump crude oil into refining tank and heat with conduction oil, and the temperature will reach about 70°C-80°C after one hour. Add acid or alkali to separate according to the acid value. After one hour's processing and 4-6 hours deposit, then convey soap stock to storage tank. (2)Pump refined oil into decoloring tank. When it is up to 90-110°c after one hour's heating, add clay into tank for 20min's processing. Then separate clay and oil with filter. (3)Put discolored oil into deodorization tank with vacuum pump. Heat and process with steam for odor removal. After filtering...
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...UNIVERSITI TUNKU ABDUL RAHMAN FACULTY OF SCIENCE DEPARTMENT OF CHEMICAL SCIENCE PERAK CAMPUS BACHELOR OF SCIENCE (HONS) CHEMISTRY YEAR 1 UDEC 1134 CHEMISTRY LABORATORY I Name: Ong En-Ming Student ID: 1404405 Title of Experiment: Determination of The Enthalpy (Heat) of Reaction of A Monobasic Acid with Sodium Hydroxide No. of Experiment: 12 Date of Experiment: 2/2/2016 Date of Submission: 24/2/2016 Group members: 1)Chong Chi Wei 2)Mong Lai Wan 3)Ang Yen Yuan Name of Lecture: Dr. Sim Yoke Leng Title: Determination of the Enthalpy (Heat) of Reaction of A Monobasic Acid with Sodium Hydroxide Objective: 1. To understand the enthalpy chemistry. 2. To determine the calorimeter constant. 3.To determine the enthalpy of reaction of acid-base reactions. Introduction: Heat is associated with nearly all chemical reactions. In such instances, the reaction either liberates heat (exothermic) or absorbs heat (endothermic). When a reaction is carried out under constant pressure (as in an open beaker) the heat associated with the reaction is known as enthalpy. The symbol for enthalpy is ΔH. It is most often too difficult to direct measure the enthalpy change for a reaction. What can be done is to measure the heat changes that occur in the surrounding by monitoring temperature changes. Conducting a reaction between two substances in aqueous solution, allows the enthalpy of the reaction to be indirectly calculated with the following equation. ...
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...converted to biodiesel. J. curcas is probably the most highly promoted oilseed crop at present in the world. The availability and sustainability of sufficient supplies of less expensive feedstock in the form of vegetable oils, particularly J. curcas and efficient processing technology to biodiesel will be crucial determinants of delivering a competitive biodiesel. Oil contents, physicochemical properties, fatty acid composition of J. curcas reported in literature are provided in this review. The fuel properties of Jatropha biodiesel are comparable to those of fossil diesel and confirm to the American and European standards. The objective of this review is to give an update on the J. curcas L. plant, the production of biodiesel from the seed oil and research attempts to improve the technology of converting vegetable oil to biodiesel and the fuel properties of the Jatropha biodiesel. The technological methods that can be used to produce biodiesel are presented together with their advantages and disadvantages. The use of lipase as biotechnological solution to alkali and acid...
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