Factors Affecting the Equilibrium Reaction of Iron (III) and Thiocyanate ions
Research Question
How does the change in temperature of Iron (III) Thiocyanatoiron, containing iron (III) ions Fe3+ (aq) and thiocyanate ions SCN¬¬- (aq), affect the absorbance of the solution?
- Temperature at 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, and 60 °C (equilibrate the Iron (III) Thiocyanatoiron (aq) in various temperatures using a digital water bath, and temperature checked using a digital thermometer connected to a data logger)
- Production rate of thiocynate ion measured by the degree of change in color using a colorimeter after 600 seconds since the reactants are mixed.
- The quantitative data of the absorbance of the solution will allow the determination of the concentration of the Iron (III) Thiocyanatoiron using the Beer–Lambert Law. The difference in concentration of the solution per temperature point provides the precise effect of temperature on the reaction’s equilibrium position.
Introduction
This experiment investigates how changing a factor that affects the equilibrium reaction, in this case temperature, affects the equilibrium position.
Fe 3+ (aq) + S︎CN – (aq) ⇌ Fe ( SCN ) 2+ (aq) ( ∆H = - ve )
Pale Yellow Colorless Blood Red
This experiment uses Iron (III) ion and thiocyanate ion; the two chemicals are yellow colored and colorless, respectively. The product of the forward reaction is Iron (III) Thiocyanatoiron, which has a blood red color.
Dynamic equilibrium is when the macroscopic properties of the reaction are in constant at a specific temperature when the rate of the forward reaction is equal to that of the reverse reaction in a closed system. (Derry, Connor & Jordan, 2009)
Le Chatelier's Principle states that the change in temperature, pressure, or concentration will cause a shift in the reversible. (Derry, Connor & Jordan, 2009) Temperature, pressure, and concentration of a chemical are factors that may cause a shift in equilibrium position; the shift is to compensate the changes made by one of the three factors.
Since the forward reaction is exothermic, the increase in temperature increases the rate of the reversed reaction, meaning more Fe 3+ (aq) and S︎CN – (aq) will be formed, thus shifting the equilibrium position to the left, so the solution will be in yellow.
In this essay, the author
Explains how the change in temperature of iron (iii) thiocyanatoiron affects the absorbance of the solution.
Compares the iron (iii) thiocyanatoiron (aq) in various temperatures using a digital water bath.
Analyzes the production rate of thiocynate ion measured by the degree of change in color using a colorimeter after 600 seconds since the reactants are mixed.
Explains that the absorbance of the solution will determine the concentration of iron (iii) thiocyanatoiron using the beer–lambert law. the difference in concentration provides the precise effect of temperature on the reaction’s equilibrium position.
Analyzes the temperature of the iron (iii) thiocyanatoiron solution containing iron ions and thiophenate ion (aq) at 25 °c, 30, 35, 40, 45, 50, 55, and 60 degrees celsius.
Analyzes the light absorbance of iron (iii) cyanatoiron (measured using the shimadzu uvmini-1240 uv-vis spectrophotometer) in order to determine the equilibrium concentration.
Explains that different spectrophotometers have slight differences in operating mechanism; the difference may cause unbalanced data collection, causing deviation in results.
Recommends turning on the shimadzu uvmini-1240 uv-vis spectrophotometer and letting it heat up for 15 minutes.
Explains how to transfer 1 cm3 blanking solution (distilled deionized water) to the 1cm3 square es quartz cuvette.
Recommends rinsing the cuvette using distilled deionized water for three times.
Explains drying the cuvette by inverting the apparatus up side down on a sheet of laboratory tissue.
Extracts 4.0 g of iron (iii) nitrate crystal to a 10 cm3 beaker, measured by the electronic balance.
Explains how to fill the 10 cm3 beaker with distilled deionized water until it reaches the 10-cm3 mark.
Explains how to turn on the hot plate without turning the heat component on.
Explains how to drop the magnetic stirrer into the 10 cm3 beaker containing the iron (iii) nitrate and distilled deionized water.
Explains how to remove the magnetic stirrer from the beaker using a magnet.
Adds additional distilled water to the conical flask, until the solution reaches a volume of 100 cm3.
Explains how to repeat stage 21 to 30 with 1.6 g of potassium thiocyanate.
Explains that after the iron (iii) nitrate and potassium thiocyanate are transferred into separate 250 cm3 conical flasks, label the conically containing alpha; and bravo.
Explains how to extract 10 cm3 solution from alpha using a volumetric pipette.
Explains how to extract 10 cm3 solution from bravo using another volumetric pipette into the other 20cm3 test tube.
Recommends placing a digital thermometer into the water bath to monitor the temperature of the digital bath.
Explains that if the temperature concurs to 25 °c, proceed to the next step.
Explains how to position the test tubes rack vertically into the water bath, with the solutions beneath the surface.
Explains how to position thermometers into both test tubes to confirm if the temperature of the solution is at 25 °c.
Explains mixing the solution from charlie into delta and starting the stopwatch simultaneously.
Recommends allowing the new solution in test tube delta to react for 10 minutes (600 seconds) in order for the equilibrium to occur.
Explains how to position the constant temperature cell holder by connecting it with the spectrophotometer’s cuvette receptacle.
Recommends extracting 1 cm3 of solution using a volumetric pipette from test tube delta into the square es quartz cuvette.
Advises to inset the cuvette into the receptacle with the clear sides facing left and right if the wavelength is set correctly.
Explains that the uvmini-1240 uv-vis spectrophotometer will automatically determine the absorbance of the solution and display it on the screen.
Explains how to record the absorbance value of the solution shown on the machine display screen into a spreadsheet document.
Recommends rinsing the cuvette three times with distilled deionized water.
Explains drying the cuvette by inverting the apparatus up side down on a sheet of laboratory tissue.
Recommends repeating stages 33 to 57 with unused test tubes. after 5 trials at the same temperature, proceed to stage 54.
Repeats stage 33 to 58 with unused test tubes. increase the temperature of the water bath and the constant temperature cell holder by 5°c each time.
Explains that after 10 trials, the iron (iii) nitrate and potassium thiocyanate solutions in the 250 cm3 conical flask made in stage 32 would be used up.
Explains derry et al. (2009) chemistry for use with the ib diploma programme standard level.
Explains precision cells' method of calibrating a spectrometer using nsg spectrophotometer calibration standards.
Explains that the experiment investigates how changing a factor that affects the equilibrium reaction, in this case temperature, impacts the balance position.
Explains that the beer–lambert law of light absorption provides a great insight to this phenomenon.
Explains that temperature should be controlled within the trial, as it is one of the factors affecting the equilibrium reaction. the digital water bath provides a temperature-monitored environment for the reactants and the solution.
Explains that chemical concentration should be controlled, as it is one of the factors affecting the equilibrium reaction. inconstant concentration of chemicals could change the final solution’s concentration.
Explains that the volume of the solution in the cuvette should always be controlled at 1.00 cm3 in order to maintain the same concentration for all trials.
Explains how the shimadzu uvmini-1240 uv-vis spectrophotometer allows experiment conductors to set the apparatus to produce light at a specific wavelength for all trials.
Explains that different electronic balances have slight discrepancies in terms of their precision to specific mass, increasing apparatus uncertainty in the experiment.
Explains that the size of the cuvette affects the results generated by the spectrophotometer. other variables ( & l) must be kept constant, as the only changing variable is a, solution absorbance.
Explains that a fixed time for each trial allows the reaction to reach equilibrium before the spectrophotometry stage.
Integrated rate laws are used to determine concentrations of reactants at certain times. However, these integrated equations can only be used after the experimental data is collected. Temperature has an effect on the rates of reactions. Swedish chemist, Svante Arrhenius, discovered that the rate constant of a reaction increased logarithmically in proportion to the reciprocal of the absolute temperature. This is expressed mathematically as:
In this essay, the author
Explains that integrated rate laws are used to determine concentrations of reactants at certain times. temperature has an effect on the rates of reactions.
Explains that the complete procedure can be found at blackboard.com under the course documents file labeled reaction kinetics.
Explains that the straight line was found to be the 1/h graphs. the reaction was a simple second order reaction.
Concludes that the reaction was simple second-order. the rate constants were 2.62 x 10-3 at 0 degrees c, and 3.22 x 10-2 at room temperature.
Explains the purpose of the experiment, which is to find the order of t-bb graphically, the k (rate constant) at 0˚ c and at room temperature, and the ea (activation energy).
Describes the process of adding water/isopropyl alcohol to a 250 ml earlenmeyer flask along with 15 drops of phenolphthalein.
However, there is no color change at end point of these reactions, so an indicator had to be added into the solutions to indicate the end point. An indicator is a chemical which is used to indicate the presence of the another substance in the solution; it changes colors when the ions H+ are added or removed by dissociation reaction. In this experiment, phenolphthalein was used as an indicator to indicate the presence of base in a solution by changing the color of the solution from colorless into pink. When the concentration of H+ is low, the solution becomes pink, and when the concentration of ions H+ is high, it becomes clear. The equivalent point is determined when there is a color change from colorless into light pink, and it is also an approximation of the end point. The concentrations were calculated by the equation M1V1 = M2V2, which means that the moles number of the base must equal to the moles number of an acid. The mole ratio in these reactions are 1:1 that means the moles’ number of the first reactant is equal to the moles’ number of the second one at the end
In this essay, the author
Explains that the purpose of experiments was to determine the concentration of sodium hydroxide by titrating with khp, and the molarity of the second solution.
Describes the reactions between bases and acids, which are both neutralization reactions and will result in salts and water as the products. an indicator is used to indicate the presence of another substance in a solution.
Explains that the mole ratio between naoh and khp is 1:1, and the molarity of the solution is equal to 0.0004.
Explains that the end point's color and molarity of each trial were less consistent than in the first experiment. the percentage of error is equal to 7.97%.
My aim in this piece of work is to see the effect of temperature on the rate of a reaction in a solution of hydrochloric acid containing sodium thiosulphate.
In this essay, the author
Explains the equation for the reaction that will occur in the experiment is: sodium thiosulphate + hydrochloric acid →
Explains the symbol equation for na2s2o3 + 2hcl →, s + so2+2na + h2ob, so that they can understand the effect of temperature on the rate of a reaction.
Explains that reactions occur when the particles of reactants collide together continuously. the minimum amount of kinetic energy required for particles at the time of collision is called the activation energy.
Explains that reactions occur in all circumstances. chemicals are always combining and breaking up. there are signs for which one can observe to notice whether a reaction has taken place or not.
Explains how iron reacts with sulphur, forming a new substance. exothermic reactions give out heat, while other reactions take in heat.
Explains how they will research the various types of chemical reactions to give them a clearer understanding of chemicals and precipitation.
Explains that two substances combine to form a single new substance, such as magnesium, oxygen, and magnesium oxide. displacement- one substance pushes another and takes its place.
Explains that when a metal reacts with an acid, it displaces all hydrogen in the solution as all acids contain hydrogen.
Describes a redox reaction where copper(ii) oxide has lost oxygen and hydrogen has gained oxygen. reduction and oxidation always happen together.
Explains that a substance splits to form simpler substances, such as calcium carbonate and calcium oxide.
Explains that the rate of a reaction is the speed at which the reaction occurs and all the rates for these chemical reactions can vary between seconds to years.
Explains the method used to measure the rate at which a product is formed, precipitate formation, and disappearance of reactants.
Explains the method used to measure the rate at which a precipitate is formed. the loss in mass of zinc and hydrochloric acid as they change into hydrogen gas is measured every 10 seconds.
Explains that to increase the rate of a reaction there are two main methods:increase the number of collisions and increase kinetic energy.
Explains that people can be compared to particles that'react' if they?bump? or collide with enough energy. if you want to increase the rate at which people react, you could either put more people into the room or ask the people to move around at faster pace.
Explains that different things affect reactions, but what affects the rates of reactions? temperature, pressure, surface area, and catalysts can change the rate of a reaction.
Explains that higher temperatures cause faster collisions, whereas lower temperatures lead to less reaction.
Explains that the concentration of a solution is how strong it is. increasing concentration increases the number of collisions so the rate of reaction goes up.
Explains how the reaction on solids with smaller particle size, for example powders or small chips, can be explained using diagrams.
Explains that catalysts speed up a reaction without being used up themselves. most reactions can use them, but for some, they do not work.
Explains that the reaction would be very slow if the catalyst manganese oxide was not added. the catalyst provides a surface and lowers the activation energy.
Predicts, after collecting scientific information on the rates of reactions, that as the temperature is increased, the rate of their reaction will also increase.
Explains that they will need to keep certain factors in their experiment constant so that it is a fair test.
Explains that the paper marked with?x? has to be the same throughout the experiment as if another one was drawn. they also state that they will need to wash the equipment used each time a trial is carried out.
Explains that they will need to be careful with glass equipment, such as beakers, flasks, and biurets. if a thermometer breaks, the laboratory must be emptied and the windows left wide open.
Describes the equipment that they will be using for their experiment — 50cm3/ml paper pen sodium hydrochloricthiosulphate acidmeasuring 2 biurets beaker tongs cylinders kettle water bath
Explains that they will follow a set procedure before conducting their experiment. they will clear their work surface of obstructions, wear goggles, and tie back loose clothing.
Explains that they will add 50cm3/ml of sodium thiosulphate using the biuret to the measuring cylinder and then pour into the beaker.
Explains that they will rinse the measuring cylinder so that no traces of hydrochloric acid remain in it when used for sodium thiosulphate. they will place their cross on the heatproof mat and place the beaker on top.
Explains that they will bring the stopwatch to their work surface and record the time taken for the reaction to fully occur.
Explains that they will set up the bunsen burner, leave the flame set on yellow flame, and place a tripod and gauze on the tripod. once the beaker and flask are dry, they'll bring them to their work surface.
Explains that they will wash the measuring cylinder, and transfer hydrochloric acid from its bottle into a measuring flask until they reach 10cm3/ml. no chemical bottles will be required.
Explains that they will fill the kettle and boil the water, then place the flask containing hydrochloric acid and place a thermometer in it.
Explains that they will place the beaker on the bunsen burner using tongs and then change the flame into a blue flame to ensure the sodium thiosulphate is heated to the desired temperature before the hydrochloric acid drops below 30°c.
Explains that they will bring the stopwatch to their work area and pour the hydrochloric acid into the beaker. they repeat steps 8 and 9.
Explains that they will repeat the experiment for a second time to obtain accurate results. each piece of equipment was effective in its purpose.
The objective of this lab is to find the equilibrium constant of Fe(SCN)2+ through multiple trials using a spectrometer. Since one chemical is colorless and the other is colored a spectrometer can be used to monitor amounts of each in the solution. By completing multiple trials an average can be reached for the value of the equilibrium constant of Fe(SCN)2+.
In this essay, the author
Explains that the lab's objective is to find the equilibrium constant of fe(scn)2+ through multiple trials using a spectrometer.
Explains the process of measuring and transferring chemicals to test tubes. the same process is used in the second part of the lab.
Explains how the lab demonstrated the process of determining equilibrium constant. the results of the experiment can be used to create a graph.
We took pictures of each other’s data once finished with the lab. For the paper chromatography, students began by grinding 5g of spinach along with 2g of anhydrous magnesium sulfate. Students added hexanes and acetone as specified by the lab protocols. Once, the solvent was a dark green color, we placed it in a centrifuge and transfer the liquid portion of the solution into a test tube. Throughout this portion of the experiment, students used weighting paper as a funnel poring the indicated solution as stated by the protocol, for instance pouring silica gel and sand into the column. After, we poured about 3ml of Hexanes into the column, making sure not to let the column dry. We then added, spinach extract to the column—after, we added about 1ml of hexanes. Adding hexanes caused the solution to gain a yellow colored band. We added hexanes until the yellow band reached the bottom of the column, thus began to collect all the yellow pigment into a test tube. Once the elutant become colorless, we once again placed a waste basket under it. Finally, we collected the green pigment into another test tube by a 70%/ 30% mixture and a bit of acetone. Once the two colored bands were collected, we obtained the wavelengths of each colored band using the
In this essay, the author
Explains that the purpose of the lab was to better understand the process of chromatography by separating different mixtures.
Explains that silica gel chromatography helps in separating compounds since they have interactions based on their nature of functional groups and the polarity of the compounds.
Explains that rf values help in identifying different compounds since a particular compound travels the same distance along the stationary phase.
Explains that from spinach, fragments of chlorophyll and beta-carotene can be extracted and identified by uv spectroscopy due to the conjugated system of double bonds in both chemicals.
Explains how one partner conducted the column chromatography experiment while the other partner performed the paper and spinach extract experiments. students used weighting paper as a funnel poring the indicated solution.
Describes the process of paper chromatography, where students placed 1-9 pencil dots at 2cm intervals along this line, dipped the end of a capillary tube in red #3 solution and applied it on dot #1.
Explains how students obtained a 9.5x14cm piece of filter paper and placed several dots. they then spotted the 3 cm spot with spinach extract, that was obtained in column chromatography.
Although the experiment produced varying results amongst the pairs of test tubes in each of the water temperatures, the Mean calculations proves that the temperature rising will increase the amount of kinetic energy in the movement of the Phosphate and Lipids in the cell membrane as well as breaking the hydrogen bonds of the proteins in the cell membrane,
In this essay, the author
Predicts that as the temperature rises, so does the amount of pigment being released.
Explains that as the temperature increases, the permeability of the cell membrane and the level of pigment being released increase.
Opines that the experiment was very controlled, but there were several variables that could have been controlled better, thus giving a higher level of accuracy and weight to the results obtained.
Recommends using a bunsen burner and thermometer controlled bath instead of an electronic water bath.
Recommends using three test tubes with samples in instead of two.
Explains the purpose of the experiment, which is to see what effects temperature has on the permeability of phospholipid bi-layer of beetroot cells and the amount of pigment released from the vacuole.
Analyzes how the experiment proved the original theory that the transference of kinetic energy to the water would cause the gaps in the cell membrane to expand, allowing the pigment to escape.
Explains that using a bunsen burner and thermometer bath enables higher control over the temperature of the water.
4. Pour hot water into one beaker and adjust the temperature to 39°C by adding colder water if needed
In this essay, the author
Describes alka seltzer, a form of aspirin in tablets, which fizzes in water due to the bicarbonate and hydrogen reacting, creating carbon dioxide to create fizzy water.
Explains how to drop one tablet in the beaker and time how long it takes to fully dissolve.
Explains that water at 16°c took the longest to dissolve the tablet at 72.88 seconds, while room temperature water took 37.18 seconds.
Explains how to remove ice cubes, drop tablets of alka-seltzer into the cold beaker of water, and time length of reaction with a stopwatch.
Explains that they set out to find out if water temperature has an effect on the length of the reaction of water and alka seltzer.
Looking at the table of results above and the graph, it is shown that the higher the temperature got, the shorter the reaction time. The obtained results have been plotted on a line graph of the temperature of hydrochloric acid (y-axis) against reaction time (x-axis). This line graph in fig.2 also clearly shows that as the temperature increases, so does the speed of the reaction, shown by a reduction in the time taken. This corroborates the collision theory, where as the temperature of particles increase, the particles gain more kinetic energy and react with each other upon collision. This is shown as to happen in the hydrochloric acid, where the hydrochloric acid particles collide more with the particles of the magnesium ribbon as the temperature was increased. The above graph shows a gradual sloping curve, which gets steeper at higher temperatures. This shows that the reaction will reach a peak rate of activity as the gaps between the temperature and reaction times continue to decrease. The experiment fulfills the aim and clearly shows that as the temperature of a reaction is increased so does it’s rate of reaction, proving the hypothesis to be correct.
In this essay, the author
Explains that chemical kinetics is the study and examination of chemical reactions regarding re-arrangement of atoms, reaction rates, effect of various variables, and more.
Explains that hydrochloric acid dissolves magnesium and produces hydrogen gas and magnesium chloride in a single displacement reaction. the reaction is irreversible.
Describes the study variables, including the extent of the reaction, the volume of hydrogen gas produced, and the temperature of hcl gas.
Explains how the temperature of hydrochloric acid affects the rate of reaction between hcl and magnesium. this hypothesis is based on the collision theory.
Explains that a lab coat must be worn to protect against acid spills, gloves should be used when handling the acid, and eye goggles should always be kept on.
Describes how the delivery tube was connected to the conical flask and then the measuring cylinder was filled with water and turned upside into the tub of water.
Describes how a 3cm piece of magnesium was cut and dropped into the conical flask. the reaction created lots of hydrogen bubbles.
Explains that the volume of hydrogen gas was recorded as the water in the measuring cylinder began to decrease at a 20 second interval, and the reaction stopped when no more hydrogen was produced.
Explains that the apparatus and materials that came into contact with the reaction were sterilised with water. the conical flask was placed in an ice bath and the initial temperature of the acid was recorded.
Explains that the experiment was carried out exactly as stated in the method. the graph shows that as the temperature of hydrochloric acid increases, so does the speed of the reaction.
Calculates the percentage yield of magnesium ribbon, which has a mass of 0.04 g and yields 40 cm3 of hydrogen when reacted with excess acid.
Argues that the same amount of hydrochloric acid and same length magnesium ribbon was used in every single trial.
Explains that the experiment was set out to find the effect of different temperatures of hydrochloric acid on the rate of reaction with magnesium.
This is the first reaction in the Harcourt Essen experiment. The iodine is oxidised to produce I2 wh...
In this essay, the author
Explains that k is a constant of proportionality and 1/t is directly proportional to the rate of reactant. the volume of ammonia molbydate is varied and the concentration of other reactants kept the same.
Describes the first reaction in the harcourt essen experiment. the iodine is oxidized to produce i2 when reacted with hydrogen peroxide.
Opines that to eliminate this inaccuracy they should have used a colorimeter to judge the end point of their experiment.
Opines that there is a possibility of human error within this experiment, such as finding the meniscus is important to get an accurate amount using graduated pipettes and burettes.
Explains the purpose of this investigation, which is to find the rate equation for the reaction between hydrogen peroxide, potassium iodide and sulphuric acid by varying the concentrations and plotting them against 1/time.
Explains the structure of hydrogen peroxide, which makes it a good oxidising agent because of the lone pair of electrons.
Explains how the first experiment investigates the order of reaction with respect to hydrogen peroxide in an uncatalysed system.