Chromatography Trail and Investigation
Chromatography Investigation Aim: I am working for a trading standards office, a local market stall is selling some red and blue sweets that are suspected of containing illegal and possibly toxic colourings. I am going to find out using chromatography whether the dyes are illegal/ legal. Chromatography is a technique which is used for separating and identifying mixtures which are coloured for example, pigments. Chromatography is the collective term for a set of laboratory techniques for the separation of mixtures. It involves passing a mixture dissolved in a mobile phase through a stationary phase, which separates the analyte to be measured from other molecules in the mixture based on differential partitioning between the mobile and stationary phases. Subtle differences in compounds partition coefficient results in differential retention on the stationary phase and thus separation. Reference: http://en.wikipedia.org/wiki/Chromatography#History Equipment List: 250ml Beaker Chromatography Paper Pencil Dyes (Red Food Colouring, Blue Food Colouring, Dylon Red, Dylon Blue) Distilled Water Capillary Tube Ruler Hairdryer Method: ) First get a ruler and pencil and then a pencil line 1cm from the bottom of the chromatography paper. Put four crosses on the line just made. 2) Using the pencil write the name of each colour dye by the matching spot. 3) Take a Capillary
How does the primary sequence of a protein dictate its structure and function?
Biology How does the primary sequence of a protein dictate its structure and function? * Explain all the different types of structures. * Use a range of proteins stating their functions linking back to their primary structure. * Use diagrams. First discovered in 1838, proteins are complex organic compounds containing the elements carbon, hydrogen, oxygen, nitrogen and sometimes sulphur. Other proteins can also form complexes with other molecules containing phosphorus, iron, zinc and copper. These are known as prosthetic groups. Proteins are macromolecules of high relative molecular mass (between several thousand and million) consisting of chains of amino acids. There are twenty different types of amino acids, as shown below with their chemical structure. These can be classified into three groups. These are polar, non polar and charged. Polar and charged amino acids will often be found on the surface of the protein interacting with the surrounding water (hydrophilic). Non polar (hydrophobic) amino acids will bury themselves in the interior. Amino acids are primary amines that contain an alpha carbon that is connected to an amino (NH3) group, a carboxyl group (COOH) and a variable side group (R) - amino acids shown above. This side group gives each amino acid a distinctive property and function. Linking an amino group to a carboxyl group on another amino acid then
Determining activation energy (Ea) of a reaction potassium between peroxodisulphate and iodine
Ho Ka Wing (9) Group: 3 Date: 09-11-09 Determining activation energy (Ea) of a reaction potassium between peroxodisulphate and iodine Objective To determine the activation energy for the reduction of peroxodisulphate(VI)ions. S2O82- (aq) by iodide ions I- , using 'clock reaction'. Theory Activation Energy (Ea)-The minimum amount of energy required to start a reaction. A certain amount of activation must be supplied to initiating a reaction (even if the reaction is exothermic) because this energy must be absorbed to weaken or even break the bond holding the atoms in the reactant particles before the bond formation. The activation energy is used to overcome the energy barrier in the reaction. If the reactants do not gain energy that is greater or equal to the activation energy, the reaction won't occur. The equation for the reduction of peroxodisulphate(VI)ions by iodide ions : S2O82- (aq)+2I-(aq) -> 2SO42-(aq) +I2(aq) The equation of the reaction between thiosulphate ions and iodine formed in the above equation: 2S2O32-(aq) +I2 (aq) ->S4O62-(aq) +2I-(aq) Controlled Variables: . Concentration of potassium peroxodisulphate(VI)solution, potassium iodide solution,sodium thiosulphate solution and starch solution 2. Volume of potassium peroxodisulphate(VI)solution, potassium iodide solution, sodium thiosulphate solution and starch solution Dependent variable: - Time
Determining the Concentration of Sulphuric acid
Salters as Practical Assessment-Plan I am going to plan an experiment to determine the accurate concentration of sulphuric acid. It is thought to have the concentration between 0.05 and 0.15 moldm-3. I will be provided with a solid base which is anhydrous (powder) sodium carbonate (Na2CO3). To find the accurate concentration I will titrate the sulphuric acid against the sodium carbonate. The reaction following will take place: Na2CO3 (aq) + H2SO4 (aq) Na 2 SO4 (aq) + CO2 (g) + H2O(l)1 Deciding the Amounts Sulphuric acid has a concentration about 0.10 moldm-3 (half way between 0.05 and 0.15 moldm-3). I would like to use 25cm3 of sulphuric acid. This is because, it is not a wasteful amount and also it would reduce percentage errors because this is quite a large amount to use. It would be an ideal value to use. Furthermore, I will need to make up a standard solution from the solid base that I have been provided with, which is sodium carbonate. I would again ideally like to use 25cm3 of the standard solution per titre. This is because, the pipettes have the reading of 25cm3, which means the pipette is readily, available for this amount, therefore it is a sensible value. Consequently I will need to make up a standard solution of concentration 0.10moldm-3. This is because of the stoichiometry. The equation shows that for every one mole of
Analysis of Two Brands of Commercial Bleaches
PLK TANG YUK TIEN COLLEGE ADVANVED LEVEL CHEMISTRY (TAS) EXPERIMENT 3 Analysis of Two Brands of Commercial Bleaches Objective To determine the concentration of sodium chlorate(I) (NaClO) in two commercial bleaches and compare the two bleaches on both concentration and price. Procedures . 10.0 cm3 of the bleach "KAO" was pipetted into a clean 250 cm3 volumetric flask. It was made up to the mark using deionized water. 2. 25.0 cm3 of the diluted solution was pipetted into a conical flask. 3. 10 cm3 of 1 M potassium iodide solution and 10 cm3 of dilute sulphuric acid was added into the conical flask also. 4. The mixture in the conical flask was titrated against the 0.0992 M sodium thiosulphate solution. 5. Three drops of freshly prepared starch indicator are added into the conical flask when the reaction mixture turned pale yellow . 6. The mixture was titrated to the end-point. 7. At the end point, the solution turned from dark blue to colourless. 8. Steps (1) to (7) were repeated with another bleach "LION" Results Concentration of standard sodium thiosulphate solution : 0.0992M Brand 1 Trade Name : KAO Bleach Price : $7.33per dm3 ($11/1500mL) Trial 2 Final burette reading / cm3 1.90 23.40 35.00 Initial burette reading / cm3 0.20 1.90 23.40 Volume of Na2S2O3 / cm3 1.70 1.50 1.60 Brand 2 Trade Name : LION Price : $6.67per dm3
Determining the Rate Equation of a Reaction
Determining the Rate Equation of a Reaction Plan The aim of this experiment is to determine the rate equation for the reaction between sodium thiosulphate and hydrochloric acid using the order of the reaction with respect to each of the reagents. HCl (aq) + Na2S2O3 (aq) --> 2NaCl (aq) + SO2 (g) + S (s) When Hydrochloric acid is added to sodium thiosulphate, a solid ppt of sulphur is formed. I will use this to judge when the reaction has ended. The rate equation for this reaction is R = k [HCl]x [Na2S2O3]y In this equation: R = the rate of reaction k = the rate constant x and y = order of reaction with respect to HCl and Na2S2O3 (e.g. 0, 1, 2 etc...) [HCl] = the concentration of HCl [Na2S2O3] = the concentration of Na2S2O3 My experiment will enable me to calculate x and y through plotting the volume against the reciprocal of the time it takes for the ppt to form. Preliminary work: The demonstration done by my teacher show that 50 cm3 of thiosulphate and 20 cm3 of deionised water mixed with 5cm3 of hydrochloric acid took 14.93 seconds to form the ppt. I will use this as a guide to decide which set of concentrations I will use to get a reasonable time which I can plot. When I implement my plan, I will plot my results. Using the shape of the graph, I will then deduce the order of the reaction. The following graphs show the shapes I should get for each order
Investigating the Volume of a Drop
IB Chemistry HL Investigating the Volume of a Drop Criteria: - Planning (a) - Planning (b) - Data Collection - Data Processing and Presentation - Conclusion and evaluation Laura Hu Lab Partner: Tu Tai Kuong Started January 20, 07 Completed January 27, 07 5 pages + raw data Planning (a) and (b) Objective: To accurately measure the volume of a drop of water and saturated salt water under two set temperatures. Hypothesis: Since the mass of a substance changes as the temperature changes, we believe that the volume of a liquid would change as temperature changes. This is because we know that density is equal to mass divided by volume. Density is different depending on its temperature and mass is constant. Therefore, with a difference in temperature, there will be a difference in volume. The second thing we predict is that salt water will have a smaller volume per drop than water. This is because the density of salt water and the mass of salt water will be greater than normal water due to the added salt in the water. This will make it heavier than regular water.. Independent Variables: Forces affecting the drop as it is about to come down (gravity and shaking of hand) Where to drop lands (may land on the sides of the beaker, making the drop stick to the sides instead of dropping to the bottom) Water evaporation Atmospheric pressure Dropping
detremining the rate equation
The determination of a rate equation Aim The aim of this experiment is to plan an experimental procedure leading to a graphical method to determine how the concentration or the volume of the components affects the rate of the reaction whose equation is given below: 2HCl(aq) + Na2S2O3(aq) --> 2NaCl(aq) + SO2(g) + S(s) + H2O(l) Introduction In this experiment in order for the reaction to take place the reactant particles must collide, and only some of those colliding particles lead to a chemical change. The rate of reaction is defined as the amount of in moles of a reactant which is used up in a given time, in this case it's the amount of sulphur formed in a given time. To work out the rate equation I will conduct two methods. In order to relate the rate of reaction with the concentration of the components involved I will have to obtain results to help me determine the rate of expression of the reaction. There are two methods used to determine the rate expression. This is done by measuring the concentration over time. The concentration has to be measured throughout the reaction. From the results obtained graphs are drawn and from that the order of the reaction is determined. The reason I'm not using this method is I don't have the right equipment to do that. The concentrations will be constantly changing and therefore
Objective; To determine the concentration of hydrogen peroxide, H2O2, in aqueous solution.
To determine the concentration of hydrogen peroxide, H2O2, in aqueous solution. In this practical examination I am provided with a '100-volume' hydrogen peroxide solution. Taking the '100-volume' into consideration I have to plan two experiments that would enable me to determine the exact concentration of H2O2, in mol dm-3. Titration: The first experiment I shall carry out will be a redox titration; between hydrogen peroxide and potassium manganate (VII). A titration will enable the reacting volumes of H2O2 and KMnO4 to be accurately determined. From this information and the stoichiometric ratio I will then be able to determine the concentration of H2O2. Prior to going into detail we must first understand what a'100-volume' solution is. By definition this means that 1cm3 of H2O2 will decompose to produce 100cm3 of O2 at STP. In simple terms it is just another way of indicating the strength of H2O2. 2H2O2 (aq) 2H2O(l) + O2(g) Equation 1. Consequently, we can understand that '100-volume' represents a very strong concentration of H2O2. Thus, before carrying out the titration the solution of H2O2 must be diluted. A reasonable dilution factor for this experiment is 100; hence from a 100-volume to a 1-volume solution. As I know the strength of the original (C1) and the new solution (C2), I can use the below formula: C1V1= C2V2 Formula 1. where V1 is
The Determination of rate equation
The determination of rate equation Aim: The aim of this investigation is to determine the rate equation of the reaction between sodium thiosulphate Na2S2O3 (aq) and hydrochloric acid HCl (aq), using a graphical method. Background information The experiment is based on the effect of varying the concentration of the respective solutions and finding out the effect it has on the rate of the reaction; in this investigation i will change both sodium thiosulphate and hydrochloric acid. When hydrochloric acid is in excess to the sodium thiosulphate, the reaction may be different to when sodium thiosulphate is in excess. This will show the effect of change in concentration on the rate of reaction. Even though the reaction equation is known, it is not possible to work out the rate equation from the reaction equation and therefore the experiment has to be conducted. Theory: The rate of a reaction can be explained in terms of the rate of decrease in concentration of a reactant or the rate of increase in concentration of a product. The most general method used to determine the rate of reaction is to measure the change in concentration of the reactant(s) per second. The rate of a reaction may be represented by a mathematical equation related to the chemical equation for a reaction. Rate equation has the form rate = k [A]x [B]y which shows how the rate of a chemical reaction
