To predict a number of redox reactions from a table of relative reactivities of some common oxidants and reductants, and then to check these predictions by experiment.
APPARATUS
The following materials are required in order to complete this experiment:,,X Reaction palette or set of semi-micro test tubes and stand,,X Clean plastic tray,,X Latex gloves,,X Goggles ,,X Set of small dropper bottles containing each of the following:
fæ Freshly prepared FeSO4
fæ 0.1M FeCl3 solution
fæ 1M sulfuric acid, H2SO4
fæ 0.1M H2O2 solution
fæ 0.1M KSCN solution
fæ 0.1M K3Fe(CN)6
fæ Freshly prepared 0.1M KI solution
fæ 0.1M sulfurous acid solution, H2SO3
fæ 0.1M K2Cr2O7
fæ Freshly prepared starch solution.
PROCEDURE
Add 10 drops of hydrogen peroxide solution to one test tube or to the palette, then a few drops of sulfuric acid. Then slowly add a few drops of iron (II) sulfate solution. Record your observations. If you predicted the formation of Fe3+ ions and a change appears to have occurred, test for the presence of the Fe3+ ions with the KSCN, as described above. Record the test result with your observations.
Continue testing the entire table by adding 10 drops of the first named substance to a fresh, clean test tube or hollow in the palette, then a few drops of sulfuric acid, then a few drops of the second named substance, drop by drop. Use one of the described tests or the natural color change of a reactant to detect or confirm if a reaction has occurred.
RESULTS
Table 1
Substance A Substance B Predicted Reaction Observations Prediction correct?
H2O2 (acidified) FeSO4 Fe2+ / Fe3+ Dark red Fe3+
H2O2 (acidified) KI I2 Brown I2
H2O2 (acidified) H2SO3 SO42- / SO3
KMnO4 (acidified) KI Mn2+ / I2 Brown I2
KMnO4 (acidified) FeSO4 Fe2+ / Fe3+ Dark red Fe3+
KMnO4 (acidified) H2SO3 SO42- / Mn2+ Brown
K2Cr2O7 (acidified) KI I2 / Cr3+ Brown I2
K2Cr2O7 (acidified) FeSO4 Fe2+ / Fe3+ / Cr3+ Dark red Fe3+
K2Cr2O7
(acidified) H2SO3 SO42- / Cr3+ Cr2+ / SO42-
FeCl3
(acidified) H2SO3 Fe2+ / Fe3+ Dark blue Fe2+
FeCl4
(acidified) KI I2 / Fe2+ / Fe3+ Dark blue Fe2+
DISCUSSION
The aim of this experiment is to predict a number or redox reactions from a table or relative reactivities of some common oxidants and reductants, and then to check these predictions by experiment. It can be said that redox reactions are those that transfer electrons. Therefore, one species accepts the electron, whilst the other loses it. The process of oxidation and reduction occur simultaneously. The oxidation number is greater in oxidation than in reduction. In addition, the E0 value in the electrochemical series for oxidation is positioned higher, and is usually a metal.
Redox reactions involve a transfer or altered sharing of electrons from one reacting species to another. If the oxidation number of an element in a reacting species changes, then that element is said to have undergone either oxidation or a reduction.
Objective: The objective of the experiment is to determine what factors cause a change in speed of a reaction. It is also to decide if the change is correlated with the balanced equation of the reaction and, therefore, predictable. To obtain a reaction, permanganate, MnO_4^(1-), must be reduced by oxalic acid, C_2 O_4 H_2. The balanced equation for the reaction is:
The purpose of this experiment was to examine how the stoichiometry, “the quantitative relationships between substances involved in a chemical reaction”, can be applied to determine the quantity of sodium hypochlorite found in a bleach product. This experiment allowed it to determine how much oxidizing agent is in a cleaner by using a redox reaction, which is a reaction involving the transfer of electrons from the compound being oxidized to the compound being reduced. To determine the amount of oxidizing agent, it is necessary to accurately measure out known amounts of redox reactants, know the stoichiometry
The procedure of the lab on day one was to get a ring stand and clamp, then put the substance in the test tube. Then put the test tube in the clamp and then get a Bunsen burner. After that put the Bunsen burner underneath the test tube to heat it. The procedure of the lab for day two was almost exactly the same, except the substances that were used were different. The
Put a label on each test tube. With a pencil, number each test tube from one to twelve.
The purpose of the experiment is to study the rate of reaction through varying of 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 rate law determines how the speed of a reaction occurs thus allowing the study of the overall mechanism formation in reactions. In the general form of the rate law it is A + B C or r=k[A]x[B]y. The rate of reaction can be affected by the concentration such as A and B in the previous equation, order of reactions, and the rate constant with each species in an overall chemical reaction. As a result, the rate law must be determined experimentally. In general, in a multi-step reac...
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Our first goal in Project 7 was to determine what our three unknown solutions were. We did this through a series of tests. Our first test was a series of anion tests. We performed anion tests to determine whether any of the following anions were present in our solution: chloride, sulfate, nitrate, carbonate, and acetate. Our first solution, labeled as B, had only the chloride test come out positive. The next solution, C, tested positive for acetate, as did our last solution, E. We next performed anion tests. These included flame test, as well as an ammonium test. For the flame test, certain cations turn flames different colors, so we used this knowledge to test to see which cations could be present in our solutions. During this test, the only solution that appeared to turn the flame any color was solution C, which turned the flame bright orange, indicating the sodium ion was present. This led us to the conclusion that solution C was sodium acetate. We next performed an ammonium test, which involved mixing our solutions with sodium hydroxide, and smelling the resulting solution in order to detect an ammonia smell. Solution B was identified as smelling like ammonia, indicating the presence of the ammonium cation. From this, we identified solution B as ammonium chloride. We next checked the pH of all three of the solutions, first by using litmus paper. Solution C was slightly basic, solution E and B were both acidic, with a pH around 4. Since we knew that solution E had acetate, and was acidic, and did not turn the flame any color, we determined it was acetic acid, as none of the ions in acetic acid would turn a flame any color.
Refer to Chemistry Lab # 2 – Investigating Changes. No changes have been made in this experiment. Methods = == ==
2.2.1. The analysis for the ability of the antioxidant activity to prevent the occurred of hydroperoxide.
In the reaction, potassium peroxodisulphate and potassium iodide will be used to provide the peroxodisulphate ions and iodide ions respectively. The ionic formula for the reaction is as follows:
... the reaction to shift to the right would be to remove products. A third way is to change the temperature. Since this is an endothermic reaction, +∆H, we can imagine that “heat” is a reactant. Thus, if we add heat, it will shift to the right. To be classified as a redox reaction, we need at least two elements to change oxidation states. The easiest way to look at a reaction and determine this is if you have an element by itself on one side of the reaction and it is in a compound on the other side. Most of the time, the oxidation number of each element in a compound is their common charge. The sum of oxidation numbers must equal the compounds overall charge. Elements in the natural state (by themselves) have an oxidation number of 0. The reducing agent is the species responsible for reducing the other chemical. Therefore, the reducing agent is oxidized itself.
The procedure for this experiment can be found in Inorganic Chemistry Lab Manual prepared by Dr. Virgil Payne.
== § Test tubes X 11 § 0.10 molar dm -3 Copper (II) Sulphate solution § distilled water § egg albumen from 3 eggs. § Syringe X 12 § colorimeter § tripod § 100ml beaker § Bunsen burner § test tube holder § safety glasses § gloves § test tube pen § test tube method = == = =
0.1M HCl, 10 mL of 0.1N KMnO4, 0.2 g. KI, 5 mL of alcohol, and 5 mL of