To determine which solvent system gives the best resolution of separation of the individual amino acids.
Ratio of volumes (Methanol: Chloroform: Water) Ds* /cm Alanine Aspartic Acid Leucine Glycine Alone In Mixture Alone In Mixture Alone In Mixture Alone In Mixture Da* /cm Rf* /cm Da* /cm Rf* /cm Da* /cm Rf* /cm Da* /cm Rf* /cm Da* /cm Rf* /cm Da* /cm Rf* /cm Da* /cm Rf* /cm Da* /cm Rf* /cm 8:1:1 4.30 9.10 0.63 8.80 0.62 6.10 0.43 5.70 0.40 1.40 0.80 1.30 0.79 6.20 0.43 5.70 0.40 :8:1 :1:8 6:2:2 2.40 8.20 0.66 7.80 0.63 4.80 0.39 4.70 0.38 1.00 0.89 0.80 0.87 5.50 0.44 4.70 0.38 2:6:2 2:2:6 4:3:3 8.80 7.50 0.85 7.60 0.86 7.30 0.83 7.50 0.85 8.30 0.94 8.00 0.91 6.60 0.75 6.40 0.73 3:4:3 3:3:4 Key: Ds represents the distance moved by the solvent up the chromatography paper Da represents the distance moved by the individual amino acid up the chromatography paper Rf represents the Rf value of the individual amino acids, that is, (Rf = Da / Ds) The asterix, * indicates the uncertainty in the values calculated, which is, + 0.05cm. Ratio of volumes (Methanol: Ammonia: Water) Ds* /cm Alanine Aspartic Acid Leucine Glycine Alone In Mixture Alone In Mixture Alone In Mixture Alone In Mixture Da* /cm Rf* /cm Da* /cm Rf* /cm Da* /cm Rf* /cm Da* /cm Rf* /cm Da* /cm Rf* /cm Da* /cm Rf* /cm Da* /cm Rf* /cm Da* /cm Rf* /cm 8:1:1 8.80 6.40
Enthalpy of formation of calcium carbonate
EXPERIMENT 6 Enthalpy of formation of calcium carbonate Objective To determine the enthalpy of formation of calcium carbonate Procedures A. Reaction of calcium with dilute hydrochloric acid . 1.0909 g of calcium metal was weighed out accurately. 2. 100 cm3 of approximately 1 M hydrochloric acid was pipetted.and placed in a plastic beaker. 3. The initial temperature of the acid was determined 4. The weighed calcium was added into the acid and stirred thoroughly with the thermometer until all the metal had reacted. 5. The maximum temperature attained by the solution was recorded. 6. The experiment was repeated with 1.0538g calcium metal. Results: Experiment no. 2 Mass of Ca used/ g .0909 .0538 Initial temp. of solution/ ? 27 26 final temp. of solution/ ? 55 52 Temperature change/ ? 28 26 Calculations and Discussion: . What does the term "heat of formation" of a substance mean? Heat of formation refers to the heat change when one mole of a substance is formed from its constituent elements is their standard states under standard conditions. 2. What are "standard conditions" for thermochemical calculations? Standard conditions is defined as elements or compounds appear in their normal physical states at a pressure of 1 atm (101325 Nm-2/760mmHg) and at temperature of 25 oC (298 K).Moreover, the solution should have unit activity(1mol dm-3 ). 3. Write
Organic Molecule – Lysine.
Lysine is one of the twenty amino acids that make up natural proteins. Eleven of these amino acids can be made by the human body from other amino acids, while the remaining nine cannot be synthesized by the body they must be derived nutritionally from protein intake - these are the "essential amino acids". Lysine is one of nine essential amino acids and therefore an important molecule as proteins are made up of a melange of most of the amino acids. Formed in plants, algae, and fungi by two distinct biosynthetic pathways (see Figures 1 and 2) it helps maintain growth, lean body mass, tissue repair and the body's store of nitrogen. Lysine is a polar molecule that has a net positive charge at physiological pH values making it one of the three basic (with respect to charge) amino acids. It therefore mostly prefers to substitute for the other positively charged amino acid arginine, though in some circumstances it will also tolerate a change to other polar amino acids. Lysine frequently plays an important role in structure. It can be considered to be somewhat amphipathic as the part of the side chain nearest to the backbone is long, carbon containing and hydrophobic, whereas the end of the side chain is positively charged. Due to this lysine is located where part of the side-chain is buried, and only the charged portion is on the outside of the protein. However, this is by no
Analysis of Neutralizing Power of Anti-acid tablets
Analysis of Neutralizing Power of Anti-acid tablets Content . Introduction 2. Work Schedule of our Project 3. Project Proposal 4. Experiment A: Investigate the neutralizing power of different brands of anti-acid tablets 4.1 Objective 4.2 Chemical Principle 4.3 Chemicals and Apparatus 4.4 Procedures 4.5 Results 4.6 Calculations 4.7 Discussion 5. Experiment B: 5.1 Objective 5.2 Chemical Principle 5.3 Chemicals and Apparatus 5.4 Procedures 5.5 Results 5.6 Calculations 5.7 Discussion 6. Conclusion 7. Reflection 8. Work List 9. Reference Introduction The reason why we chose this experiment is because we are very familiar with the topic on neutralization since we have been studying it for a few years. So, we have more confidence in dealing the problems that might occur when we perform the experiment. Although we seldom use anti-acid tablets to relieve our stomachache, it is still a very good opportunity to know more about these drugs. As we all know, Hong Kong people are usually under stress, having stomachache is thus very common. Under a plethora of anti-acid tablet brands available in the market, it is really difficult for us to choose the best buy. Therefore, we would like to investigate which brands of anti-acid tablets could help the most. We plan to spread our results to our friends and relatives so that they could not only save money, but also
Chemistry Open-book Paper - Periodic table and Atomic structure
Chemistry Open-book Paper In 1817 a scientist by the name of Johann Dobereiner was the first to attempt to classify elements using their relative atomic mass. He found that some elements had similar properties, and put them into a group called a triad, for instance Li, Na and K. He found that the middle element in each group had a mass which is equal to the average of the other two. This also applies to several other groups. The British chemist, John Newlands arranged the elements in order of relative atomic mass in 1866. H Li Be B C N O F Na Mg Al Si P S Cl K Ca Newlands noticed that similar elements appeared at regular intervals in the list. He arranged the elements in the following columns: H Li Be B C N O F Na Mg Al Si P S Cl K Ca Cr Ti Ma Fe Newlands drew up a law of octaves where by he compared his chemical 'octaves' with musical octaves. It was a Russian chemist, Dimitri Mendeleev, who developed Newlands idea and persuaded chemists to use it. Mendeleev summarised his periodic law in the statement: "The properties of chemical elements are not arbitrary, but vary with their relative atomic masses in a systematic way". Mendeleev's Periodic Table of 1871 He arranged the elements in his periodic table by increasing a relative atomic mass. His periodic table is still used today but is updated. Two spaces were
I predict that the juice will have at least 2 or more of the same amino acids as the ones in the amino acid mix. I predict that the amino acid more likely to occur is aspartic acid, as lemon juice is acidic.
CHROMATOGRAPHY Hypothesis I predict that the juice will have at least 2 or more of the same amino acids as the ones in the amino acid mix. I predict that the amino acid more likely to occur is aspartic acid, as lemon juice is acidic. Method * We first extract some lemon juice from a lemon. Cut the lemon around the equator and squeeze it with a juicer. * Pour the juice into six tubes at approximately the same level each. * Place the tubes in a beaker and weigh them (remembering to tare the beaker first). Make pairs of tubes of equal mass by adding or taking out juice with a clean pipette) and place them opposite each other in the centrifuge and set it to run for 5 minutes. * After centrifuging the juice, pour all the supernatant into a beaker and wash out the solid precipitate from the tubes. * Take 2 samples of the raw centrifuged juice in tubes, label and put them away. * Add alcohol to the remaining juice with the ratio of 1:3 (1unit of juice to 3 units of alcohol). * Centrifuge the juice + alcohol after weighing out pairs of equal mass in the tubes again. * Pour the supernatant into a beaker and take 2 samples if the juice + alcohol, label them and put them in a beaker to be put away. Results of centrifuged juice: Pair no. Mass of 1st tube Mass of 2nd tube Places in centrifuge 1 7.85g 7.85g 1,7 2
Aspirin-its preparation, history and applications
Aspirin-its preparation, history and applications * How drugs are discovered and developed Pharmacologist along with chemist focus on a specific disease and unmet patient needs in order to discover new drugs. They search for biological targets within the body that play a role in a given disease. Unique molecules are found or created that some day might be medicines. Lead Compound Selection, is the testing of compounds that might undergo the long expensive drug develop process. Random Screening- uses existing 'library' of chemical agents. This is the simplest method but the odds are low and patience is needed. Combinational Chemistry Screening- uses a compound (from existing library) as a base, then randomly adding amino acids or molecule segments of other agents to the base compound in order to enhance the base compounds activity and disease fighting potential. The enhanced compounds are then tested in rapid screening test. However this method is complex and costly but it improves the odds. Target Synthesis- targets the disease for drug intervention. For example High Blood Pressure would be studied in detail. Consequently this method still requires screening of hundreds of compounds and extensive amount of research to understand a particular disease process. Drug Modeling- uses more high technology. This method manipulates chemical structures by computers so that they
Chromatography experiment.
20/10/01 Chromatography Experiment by Emma Walters Aim: To identify different unknown amino acids, within given substances. Apparatus: List 1 List 2 * 2 test tubes * Test tube rack * 2 bungs * 2 pins * 5 known amino acids: * Proline * Leucine * Lycine * Asparagine * Arginine * 1 unknown amino acid * Paper Chromatography * Paper Solvent * Pencil * Ruler * Tweezers * Paper Towel * Pipette * Ninhydrin * Incubator * Scissors * 1 Jam Jar * Treated Orange Juice * Untreated Orange Juice * TLC * TLC Solvent * Pencil * Ruler * Tweezers * Pipette * Paper Towel * Ninhydrin * Incubator Diagram 1: Diagram 2: Method (Part 1): * Cut 2 strips of paper chromatography using tweezers and scissors while resting on paper towel * Measure 1cm from bottom of strip and draw a line across * Draw a cross in the centre of this line * Attach a pin to the top of the chromatography paper, and put pin in bung * Place inside test tube, and measure 5mm from where the bottom of the paper lies, draw a line across the test tube * Do the same with both strips * On the cross put 10 drops of a known amino acid, wait for each drop to dry in between * On other strip put 10 drops of unknown amino acid * Pour paper solvent into both test tubes up to line drawn * Put bung in both test tubes, let solvent
Open Book Paper 2008
Chemistry (Salters) Skills for Chemistry: Open-Book Paper In radioactive decay, atomic nuclei play an important part in ?- and ?-decay. ?-decay involves the disintegration of an atomic nucleus to emit the ?-particle, whereas in ?-decay, a neutron inside the atomic nucleus is converted into a proton and an electron, which is released as the ?-particle. The particles released are different as well, since the ?-particle is made from two protons and two neutrons, similar to a helium-4 particle and the ?-particle is an electron. This means that if different elements are formed if the same element went through ?- and ?-decay. ?-decay 224Ra88 --> 220Rn86 + 4He2 ?-decay 225Ra88 --> 225Ac89 + 0e--1 ?-decay can happen to any element, from the smallest and lightest, to the largest and heaviest, while ?-decay only usually happens in the heavier elements. It usually does not happen in elements with atomic numbers smaller than 83[1]. This means that ?-decay usually does not continue past Bismuth and its' isotopes, whereas ?-decay can go all the way to Hydrogen-3, or Tritium (T)[2]: 3T1 --> 3He2 + 0e--1 Radioactive decay is different to Nuclear Fission by the way that the atomic nucleus acts. In Nuclear fission, the nucleus splits after the addition of a neutron, while in Radioactive decay, the nucleus starts off unstable and decomposes. The half-life of elements is also
The enthalpies of combustion are different depending on the number of carbons and hydrogens in each substance. For example, the enthalpy combustion for methane is -890 kJ mol-1, however the enthalpy change of combustion for ethane or propane will be grea
Introduction on enthalpy of combustion Standard enthalpy change of combustion is the energy change that occurs when 1 mol of fuel is completely burnt in oxygen under standard conditions. However, it is impossible for substances to be burnt under standard conditions. The enthalpies of combustion are different depending on the number of carbons and hydrogens in each substance. For example, the enthalpy combustion for methane is -890 kJ mol-1, however the enthalpy change of combustion for ethane or propane will be greater because more bonds are involved and therefore more bonds are broken and made. All combustion reactions are exothermic because energy is given out to make bonds. Figure 1: Exothermic reaction Before you start doing calculations for enthalpy change of combustion you firstly need to balance the equation. For example: Methane CH4 (g) + 2O2 (g) 2H2O (g) + CO2 (g) Also it is important to note when making a combustion reaction balanced equation that the state symbols for all the substances are gaseous even water. Moreover, it is only in a combustion reaction that you use halves in an oxygen molecule. An example for octane is: C8H12 (g) + 12.5O2 (g) 8CO2 (g) + 9H2O (g) Method for the enthalpy of combustion for various alcohols . Set up a tri pod and place tiles around it. 2. Fill up a metal calorimeter with 200
