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.
4. Pour hot water into one beaker and adjust the temperature to 39°C by adding colder water if needed
In terms of kinetics, specifically speaking, the rate of reaction as determined by the concentration, reaction orders, and rate constant with each species in a chemical reaction. By using the concentration of the catalyst and the temperature, the overall reaction rate was determined. The rate constants of K0, Kobs, and Kcat can be derived via the plotting of the absorption at 400nm of p-nitrophenol vs. the concentration of the catalyst imidazole. Lastly, the free energy of activation, G, that is necessary to force the reactant’s transformation of the reactant to the transition state structure will be determined by using the equation G = H – TS derived from the Eyring plot. Introduction: The purpose of the experiment is to study the rate of reaction through varying concentrations of a catalyst or temperatures with a constant pH, and through the data obtained the rate law, constants, and activation energies can be experimentally determined.
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+.
... : The difference in slope is positively correlated with a lower temperature. This slope becomes apparent
to an unfavorable free energy change for the process. Once added to a system, before equilibrium
Our most basic knowledge of chemical equilibria comes from a French man named Henry-Louis Le Chatelier. Through his studies of equlibria and the effects of changes provoked on these equilibria, he was able to come up with a principle that is studied widely today. Le Chatelier’s Principle, which was named after him, states that a change in one of the variables in a system at equilibrium will cause a shift in the position of the equilibrium that counteracts this system. Le Chatelier’s Principle is aimed at three changes that can cause a disruption in a system at equilibrium. These three changes include a change in the temperature of a reaction, a change in the concentration of one of the variable of a reaction, and a change in the pressure on a system. [1]
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
• An increase in the temperature of the system will increase the rate of reaction. Again, using the Maxwell-Boltzmann distribution diagram, we can see how the temperature affects the reaction rate by seeing that an increase in temperature increases the average amount of energy of the reacting particles, thus giving more particles sufficient energy to react.
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,
The aim of this investigation is to: 1) find the rate equation for the reaction between hydrogen peroxide, potassium iodide and sulphuric acid by using the iodine stop clock method and plotting graphs of 1/time against concentration for each variable. Then to find the activation energy by carrying out the experiment at different temperatures using constant amounts of each reactant and then by plotting a graph of in 1/t against I/T, 3) to deduce as much information about the mechanism as possible from the rate equation.
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.
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
When a metal cation (M) reacts with a ligand (L) a complex forms. The ligand acts as a Lewis base in the reaction and forms a coordinate covalent bond as the ligands lone pair goes to an empty orbital within the metal. To illustrate this: xM + yL → MxLy where x and y are stoichiometric ratios. To determine the ratios it is possible to use Job’s method. Also known as continuous variance, Job’s method carefully used reactant mixtures such that the total moles and volumes of reactants are constant [Harris, 2010].When just enough of the metal and ligand react the most product is formed. Measuring the absorbance of each solution, the absorbance can be plotted versus a mole fraction of metal or ligand. Using the two resulting equations the mole ratio can be determined. Absorbance is measured by ultraviolet-visible spectroscopy. This method uses visible light and ultraviolet light to excite an electron within a molecule. This will release a photon colored as what colors the molecule doesn’t absorb as the electron returns to its previous energy level. The UV-vis spectroscopic machine then uses this to measure absorbance [Misra 2002]. In this experiment, iron (II) will react with 1, 10-phenanthroline (shown below) to form iron (II)-phenanthroline. This reaction is shown as:
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.
No matter what the third body is, if the first and second bodies are in equilibrium, the third follows that pattern. The property of temperature in this law is a crucial cause of equilibrium due to the fact that increasing or decreasing the temperature varies the energy by creating disorder when it is absorbed into the body and disperses. For this law, “[w]hat is important is that the Zeroth Law establishes that temperature is a fundamental and measurable property of matter” and “it supersede[s] the other three laws” (“What is the Zeroth Law of Thermodynamics?”). In several reactions, especially in chemical reaction, temperature plays a major role in all of it. A potential comparison is that if a person shares a room with another person and both are organized, they will organize their room to their standards. The two people compare to the two bodies that are at equilibrium and the third body achieves equilibrium with the other two. In this case, organization is the property to achieve that equilibrium. In addition, relating to the first law, the transfer of energy can have increased strength based on the temperature such as in electricity in different reactions in the light bulbs. For the second law, energy relates to entropy where temperature can increase the energy that can increase the entropy, leading to further chaos and havoc.