Primary and Secondary Standard solutions in chemistry (titration & colorimetry)
Primary standards, such as potassium hydrogen phthalate (KHP) (C8H5KO4), display unique characteristics such as high purity, maintain stability during storage within a long period of time whether in solid or liquid form, large molar mass as calculated to be 204 (RMM), low reactivity with the surrounding air, high stoichiometry and low hygroscopicity (property of absorbing water from its surroundings), which makes them ideal in making precise assessments of the unknown concentration of a known chemical. Secondary standards such as sodium hydroxide (NaOH) do not have the properties listed above, therefore it is low in purity, it is highly liable in absorbing the water molecules (H2O) from the atmosphere, it has high reactivity, it’s concentration changes over time, has lower molar mass known to be 40 (RMM). They are used in standardisations by comparing against primary standards. Primary standards are high in purity; whereas secondary standards have a low purity. Primary standards such as potassium hydrogen phthalate (C8H5KO4) remain stable when stored and the concentration does not alter over time whether it is in solid form or liquid form; however, secondary standards, for e.g. sodium hydroxide (NaOH), does not remain stable and the concentration changes rapidly over time. The primary standard, potassium hydrogen phthalate for example, has a higher molar mass (204 RMM)
Comparing High Pressure Liquid Chromatography and Gas Chromatography
Comparing High Pressure Liquid Chromatography and Gas Chromatography HPLC and GC have different approaches to separating components in mixtures. HPLC deals with separating particularly non-volatile and liquid substances such as ions, polymers and other complex structured molecules into their components; whereas, GC deals with volatile and gaseous substances or the substances could be vaporised (organic or inorganic molecules such as alcohols) while they are in the injection unit. In HPLC high pressures are given from a pump in order to force the mobile phase through the column and interact with the components within the mixture. This is because compounds that react very slowly due to their complex structure are being separated within the column. A vacuum degasser is also present in HPLC and it removes the air bubbles that are in the mobile phase; otherwise these air bubbles will give false peaks in the chromatogram. On the other hand, Gas Chromatography, highly volatile substances such as alcohols are being separated in a mixture, therefore a very high pressure is not necessary because in GC the components are volatile and they do not have to be forced to interact with the mobile phase and the stationary phase because the components themselves are reactive; instead components travel through the stationary phase with capillary action. Heat is being used instead in GC to turn
AQA As Applied Science Unit 3. Colorimetry experiment on Ribena juices
Colorimetry Aim: * The aim behind this science is to measure colours and to predominantly quantify the colour of light sources or objects from visual colour matches. (This means that the eye(s) are used as a tool to identify if the colour is identical or not. Scenario: I am a scientist, my first task is to go into a laboratory and test the concentrations of different Ribena juices, then I am going to find out the unknown dilutions for both Tesco and Asda Ribenas. Hypothesis: The more expensive the higher quality it will be therefore the stronger the concentration of the drink. The cheaper the Ribena juice the lower quality it will be therefore a weaker concentration of the drink. Scientific Background: A specific solution will be used to measure and determine the absorbance of particular wavelengths of light by a specific solution. This is the procedure is used to measure the amount of light something absorbs, this is then measured in units of absorbance, this is also directly proportional to its concentration, this method is used to determine concentration. Colorimetry is also the technology and science used to quantify and describe the human colour perception. What is colorimetry used for? Colorimetry is used in most industries such as: * Food * Paint manufacturing * Colour printing * Textile manufacturing * Chemistry ASDA Equipment: * Ribena *
Comparing the commercial production process of iron and aluminium in relation to their properties
Comparing the commercial production process of iron and aluminium in relation to their properties The molten iron is usually used in moulded into cast or pig iron and transformed into many kind of steel, some of which includes stainless steel, high speed steel or chromium steel. During the transformation of iron and aluminium into these products, these elements go through two production processes, the batch process and the continuous process. The cost of extracting these metals can be extremely high because of the high amount of electricity that it requires. The continuous process is used to manufacture iron because of its high demand in the industry and this demand is due to its good quality and ability around other substances, heat and electricity. The manufacture of aluminium can be done through both processes depending on the rise of its demands in the market and industry where it is mostly used. Continuous process In the continuous process, the production is always running 27/7 and it never stops. The continuous production process is mostly used to manufacture large quantity of chemicals needed. An example of a continuous production process is the Haber process. This production process is used to manufacture Ammonia. The rate of production in the continuous process is much more higher compared to the rate of production in the batch process simply because the
Purification of aluminium from Bauxite
Purification of aluminium from Bauxite http://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Bayer-process-en.svg/500px-Bayer-process-en.svg.png Key features of the production process * First, we have the crushing stage which enables people to separate the metal-rich ore from the other rocks that are attached to it * The ore is roasted sometimes which helps remove sulphur * The metal goes through electrolysis to be able to extract the aluminium. But first is melted through molten cryolite so that the electricity can be able to pass through it. This is done to in order to ease the melting of the aluminium because it has a really high melting point of 660.3 °C because of the strong bonds between atoms. If it was to by processed without cryolite if would take too much electricity which would be a waste. * The metal is finally extracted; it can be cast and rolled. Sometimes other metals are added to it while it is molten in order to make alloys with useful properties. Overall process Mine bauxite – mix with cryolite – met by electrolysis- lower anodes into electrolysis – pass large electric current- tap off molten aluminium – replace carbon anodes http://www.elmhurst.edu/~chm/onlcourse/chm110/outlines/images/elecaluminum.GIF http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/electrolysis/electrolysisrev3.shtml The final product (aluminium) is
Investigation (reaction of transition metal ions)
Investigation (reaction of transition metal ions) Aim- To find how hexaqua ions reacts with various substances (other ions) Equipment * Goggles * Apron * 5 test tubes * Beaker * Pipette * Hydrochloric acid * Copper hexaqua * Cobalt hexaqua * Chromium hexaqua * Ammonia * Sodium Hydroxide * sodium carbonate Method- * We collected our five boiling tubes and set them up in the test tube rack * We collected the ion we were going to use (the cobalt) and measured about 5cm of it and poured it in each of the boiling tubes * We put a few drops of HCL in each of the boiling tubes containing the cobalt, we then had to swirl the solution and observe what was happening, then add a few more drops to excess it and see how it changes * We noted the results of what we observed in a table like the one below * We Repeated the same process with other chemical ions (chromium and copper) Results Hexaqua ions Ph. HCL Ammonia Sodium Hydroxide Sodium carbonate Cobalt (red) Ph3 Blue. Produced heat, and smoke Went cloudy, produced a blue precipitate Light blue cloudy and dark Light pink Precipitate, cloudy liquid Copper (bleu) Ph1 Colour change to slightly green Light blue Slightly warm Cloudy Light blue, foamy state, and slightly warm Light blue, foamy, produces a fizzy sound, goes a bit warm Chromium (green) Ph1 Greyish Dark green, grey,
Rates of reaction experiment HCl and Sodium Thiosulphate
Rate of reactions The rate of reactions is how fast something changes from its reactants to its products. For a reactions to occur, the particles must strike with enough energy. At the start of the practical only some of the reactions will have enough energy to strike with each other and create energy for the reaction to happen. We can increase the rate of reaction by changing specific conditions in order to increase the rate of collision what will happen is that one of the things what can change it is the temperature because it provides the reactant with more energy. So this means the particles will be moving around more and therefore they are more likely to collide with each other. Another one is the concentration because by increasing the concentration of a reactant we are increasing the number of particles in a certain volume. This means there is more likely to be more collisions because they is more particles with in a small space. Another one could be pressure because by increasing the pressure we are decreasing the space in what the practices can move about in. so this means the practices will be more likely to collide with each other because there is less space for them to move around. Another one could be a catalyst because this is a lower activation energy required by particles to start a reaction and provides another route for the reaction to occur, thus speeding
Assignment 2 M3 Specialist and Non specialist lab
Assignment 2 M3 In this assignment I am going to compare a non-specialist and a specialist laboratory. Non-Specialist Laboratory: An example of a non-specialist laboratory would be a school science laboratory; the lab would have standard safety equipment such as safety goggles, protective clothing, aprons and gloves. The lab will only have equipment needed for a practical the students will be carrying out so the equipment they will use equipment such as Bunsen burner, test tubes, test tube racks, stands and clamps, thermometer and for a different experiment the students might use equipment such as power packs, batteries, cell holder and bulbs. The science lab will have a first aid kit and eye wash stations. The lab will also have other safety equipment such as fire extinguisher, fire blanket and a sand bucket. This kind of lab would be used by secondary school students to carry out general practicals such as animal dissections, titrations of a chemical and testing electric circuit for voltage and current change. My non-specialist lab has the following equipment: * New fast and efficient computers to be able to do research and type up work * New student benches with integrated gas taps and plug sockets so that they are easily accessible during a practical. * New teachers’ desk with draws and cupboard built in so storing documents and work is easy and also easily
The estimation of iron(II) and iron(III) in a mixture containing both
The estimation of iron(II) and iron(III) in a mixture containing both I have been given a solution that contains between 1.1g and 1.3g of iron ions; they are in a mixture of both Fe2+ and Fe3+. My aim is to work out the percentage of each of them in the solution. With my research I have found out that the best method would be to find out how many grams of Fe2+ ions there are first. I must then convert all the Fe3+ ions in to Fe2+ ions by reducing them with granulated zinc and H2SO4. This would enable me to then work out the total mass of all the iron ions in the solution. Total Mass - Mass of Fe2+ = Mass of Fe3+ After I know the mass of each different iron ion in the solution I can then convert these into percentages. Equipment 200cm3 of Fe2+/Fe3+ solution H2SO4 (1 mol dm-3) KMnO4 (0.0100 mol dm-3) Clamp stand Beaker Eye protection Burette White tile Graduated pipette Accuracy I am using 20cm3 of my solution each time as opposed to using 10cm3 as this will give me a lower percentage error. I will make sure all equipment I use is clean. When measuring out any amounts of solutions or acids I will always use a graduated pipette as these are the most accurate ones I can use. I will use the white tile as it will enable me to detect the slightest colour change. Safety It is vital that all actions are carried out safely to make sure that no harm comes to me or
the determination of a rate equation
The determination of a rate equation: Skill P This experiment will involve the determination of a rate equation derived from experimental data. The experiment will involve the reaction between hydrochloric acid and sodium thiosulphate. 2HCl(aq) + Na2S2O3(aq) › 2NaCl(aq) + SO2(aq) + S(s) + H2O(l) Background theory (1, 2, 3, 5): The rate expression tells us how the rate of reaction depends on the concentration of the species involved. The generalised equation for this experiment: Rate= k [HCl(aq)]a [Na2S2O3(aq)]b The orders of reaction, a, b and c, have to be determined by experiment. a and b are constants whose values are usually 0, 1 or 2, and k is the rate constant. The rate constant is the proportionality constant k in a rate equation. a is the order of reaction with respect to reactant HCl, and b is the order of reaction with respect to sodium thiosulphate. The overall order of reaction is the sum of the powers of the concentrations of the two individual reactants, hydrochloric acid and sodium thiosulphate, in the rate equation, that is (a+ b). By rate of reaction we mean the change in concentration of a reactant (or a product) in a given period of time. Order of a reaction is the power to which we have to raise the concentration to fit the rate equation. There are three main orders of reactions: zero-order, first-order and second-order of reaction. When
