Phenolphthalein) is used to show the equivalence point has reached by changing colours. Titration experiments are used to determine the concentration of an acid or a base, if either acid or base concentration known, the other unknown concentration can be find out by measuring how much it takes to neutralize, which is a useful experiment. The Bronsted-Lawry theory about acid and base, describes as follows; an acid a proton (hydrogen ion) donor, a base is a proton (hydrogen ion) acceptor, or any component that can transfer proton to any other component is and acid and any component that accepts the proton is base. The theory says a substance can function as an acid only when a base is presented, and also other way round, a substance can only function as a base in the present of an acid. This theory consider a large
Purpose The main objective of this lab is to use qualitative analysis to understand and recognize the chemical properties of certain Group 1 cations, which are Ag+, Pb2+, and Hg2+, and to use their inherent properties to identify whether they are present in an unknown sample. These three particular cations, known as the Silver Group, can be separated and isolated from each other by forming insoluble chloride salts. Introduction Chemistry is an analytical science, which is based heavily on experimentation and observation. The data that can be obtained through experimentation can be separated into two distinct types of data: qualitative and quantitative. Quantitative data deals primarily with numerical characteristics, such as the weight or amount of a particular substance.
37 Rb Rubidium 85.4678 Atomic Number: 37 Atomic Weight: 85.4678 Melting Point: 312.46 K (39.31°C or 102.76°F) Boiling Point: 961 K (688°C or 1270°F) Density: 1.53 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 5 Group Number: 1 Group Name: Alkali Metal What's in a name? From the Latin word for deepest red, rubidus. Say what? Rubidium is pronounced as roo-BID-i-em. History and Uses: Rubidium was discovered by the German chemists Robert Bunsen and Gustav Kirchoff in 1861 while analyzing samples of the mineral lepidolite (KLi2Al(Al, Si)3O10(F, OH)2) with a device called a spectroscope.
Acid and Base Titration Aim: To determine the concentration of a dilute solution of sodium hydroxide which is approximately 0.1 mol dm-3 Introduction: Titration is an example of redox reaction and is a process of chemical analysis in which the quantity of some constituent of a sample is determined by adding to the measured sample an exactly known quantity of another substance with which the desired constituent reacts in a definite, known proportion. The process involves the gradual adding of standard solution of titrating reagent from a burette. The addition is stopped when the equivalence point is reached. From this point an exact equivalent of titrant will be added to the earlier solution. The completion of the reaction is marked by some signal; this signifies the end point.
The Ka expression, Ka=H+In-HIn [1] (1) is the equilibrium for the dissociation of the weak acid, where HIn is the acid and In- is the conjugate base. This is represented by the chemical equation: HIn ⇌H++ In- [1]Figure 1: Chemical equation for the dissociation of an acid-base indicator. Methyl red is a monoprotic organic acid. Figure 2 is a structural model of methyl red. Figure 2: Chemical structure of methyl red By plotting the data as the pH versus the log term of the Henderson-Hasselbach Equation, pH=pKa+logIn-HIn [2] (2) the pKa was
Name : Syahrul Anwar Bin Jamaludin Student ID : J13012996 Date of Experiment : Partner’s name : Chong yen leng Title QUALITATTIVE ANALYSIS OF CATIONS (2) Mn2+, Ni2+, Fe3+, (Fe2+), Al3+ and Zn2+ Aim To identify the presence of common transition metal cations using qualitative analysis Procedure Please refer to CHM152 lab manual procedures page 27-31 Results Procedure Number and Ion | Test reagent of Technique | Evidence of Chemical Change | ChemicalResponsible for observation | Equation(s) for observed reaction | 1 | Centrifugation | Brown-Black Precipitate | Mn(OH)2Ni(OH)2Fe(OH)2 | Mn2+ + 2OH- → Mn(OH)2Ni2+ + 2OH- → Ni(OH)2Fe3+ + 3OH → Fe(OH)3 | 2 | Decanting | Light yellow solution | [Al(OH)4]-[Zn(OH)4]2- | Zn2+ + 4OH- ↔[Zn(OH)4]2- Al3+ +4OH ↔[Al(OH)4]- | 3 | Concentrated NH3 | Dissolved precipitate | Mn2+, Ni2+, Fe3+ | Mn(OH)2→ Mn2+ +2OH-Ni(OH)2→ Ni2+ +2OH-Fe(OH)3→ Fe3+ +3OH- | 4 (Mn2+) | NaBiO3 | Deep purple solution | MnO4- | 2Mn2+ +5BiO- + 14H+ → 2MnO4-+ 5Bi3+ + 7H2O | 5 (Fe3+(2+)) | Concentrated NH3 | Precipitate with colorless solution | Fe(OH)3[Ni(NH3)6]2+ | Fe3+ + 3NH3 +3H2O→ Fe(OH) Fe(OH)3 +3NH4+ | 6 | Decanting | Clear solution | | Ni2+ +6NH3 →[Ni(NH3)6]2+ | 7 | HCl, NH4SCN | Blood red precipitate | Fe3+ | Fe3+ + SCN- → [FeNCS]2+ | 8 (Ni2+) | H2DMG | Pink precipitate | H2DMG | [Ni(NH3)6]2+ +2H2DMG → Ni(HDMG)2 + 2NH4+ +4NH3 | 9 (Ai3+) | Ammonia | Gelatinous solution | Ammonia | [Al(OH)4]- +4H+ → Al3++ 4H2O + 3NH3 → Al(OH)3 + 3NH4+ + H2O | 10 | Centrifuge & Decant | Dark precipitate | Al(OH)3[Zn(NH3)4]2+ | [Zn(OH)4]2- + 4H+ → Zn2+ + 4H2O + 4NH3 → [Zn(NH3)4]2+ | 11 | NH3 | Red precipitate | Al(OH)3 | Al3+ +3NH3 + 3H2O + aluminon → Al(OH)3. aluminon + 3NH4+ | 12 (Zn2+) | K4[Fe(CN)6] | Light green precipitate | Zn2+ | 3[Zn(NH3)4]2+ + 4NH+ → 3Zn2+ + 4NH4+ + 2K4[Fe(CN)6] → K2Zn3[Fe(CN)6]2 + 6K+ | Conclusions The
Another bottle from the same laboratory is labeled “Compound B (isomer of A).” Compound B also reacts with 1 mol equiv of hydrogen, but yields cyclohexanone after treatment with acidic [pic]. a. Suggest structures for A and B. Answer: b. What was the other product formed in the [pic] oxidation of B?
Assessed Practical: Planning Introduction: The aim of this experiment is to find the enthalpy change for the decomposition of sodium hydrogen carbonate. 2NaHCO = Na2CO3 + CO2 + H2O Using the enthalpy change of the following reactions. Sodium Hydrogen Carbonate: NaHCO3 + HCl = NaCl + CO2 + H2O Sodium carbonate: Na2CO3 + 2HCl = 2NaCl + CO2 + H2O Apparatus Sodium hydrogen carbonate Sodium carbonate Polystyrene Cup x 2 Measuring cylinder 50cm³ x 2 Weighing scale Weighing boats Thermometer degrees Spatula HCl acid 2M Prediction Background Information Hess' Law states that the enthalpy change for a reaction is the same whether the reaction occurs directly or in steps. This is a direct consequence of the fact that enthalpy, is a state function. One of the applications of Hess' Law is to determine the enthalpy change for a reaction by combining other reactions to get the desired reaction, then combining the enthalpy changes for the reactions to get delta H for the reaction under consideration.
UNIVERSITI TUNKU ABDUL RAHMAN Faculty Course Year/ Semester Session : : : : Faculty of Science Bac. of Science (Hons) Chemistry Year 3 Semester 1 201105 or May 2011 Unit Code Unit Title Lecturer Assignment : : : : UDEC3254 Spectroscopy and Chromatography II Dr. Lim Chan Kiang 2 Answer all questions 1. A mixture of steroid hormones consisting of cortisone, cortexone and corticosterone was separated using a HPLC silica column eluted with a binary mixture of acetone and hexane (20:80). (i) What is the order of elution time for the above compounds from the HPLC column? (3 marks) (ii) What is the chromatographic mechanism involved?
Title Page Experiment Title: Experiment 4: Qualitative Analysis of Cations III – Mg2+, Ca2+, Fe3+, Ba2+. Aim To determine the presence of the cation II , Mn2+, Ni2+, Fe3+, (Fe2+), Al3+, Zn2+ by using separation method to confirm the presence of cation II in the test solution. Procedure Please refer to the laboratory manual page 30-31. Results Procedure Number and Ion | Test Reagent or Technique | Evidence of Chemical Change | Chemical(s) Responsible for Observation | Equation(s) for Observed Reaction | 1 | Centrifuge the solution. | A brown precipitate was formed.