The reduction reaction is the opposite of the oxidation reaction. In oxidation reactions, atoms gain electrons and atoms or molecules are transformed into new compounds. In comparison, in reduction reactions, atoms lose electrons and are transformed into new compounds.
Reduction reactions are typically described as the combination of a metal with a compound to form a new metal compound and electrons. These electron transfers make up the voltage of a cell which forces chemical change.
Sodium nitrate is a salt that has been used for many different applications. It has been used in food preservatives, in tobacco production for aroma, and in textile dyeing applications. For these uses, sodium nitrate is first synthesized from sodium chloride (common table salt) and nitric acid.
These processes require efficient sodium nitrate synthesis to ensure there is enough material for production. There are many ways to improve sodium nitrate synthesis, but one way is to use better filters during the reaction process.
List the reactants
Reactants are the molecules or ions that react with each other to form new compounds or molecular structures. In this case, the fluorine ion (fluoride), the sodium ion (sodium), and the iodine atom (iodine) will be used to form a new compound, tellurium.
Tellurium is a metalloid, which is a classification of elements that fall in between metals and nonmetals. Tellurium has several uses, one being in electronics. It is a part of some electronic devices such as TVs and computers.
To list the reactants for this reaction, we will have to break down what happens when fluoride, sodium, and iodine interact. First, fluoride and sodium ions will interact and form sodium fluoride. Then, iodine will interact with the sodium fluoride to form tellurium atoms.
List the products
In this reaction, the atoms in the sodium chloride dissociate and form sodium ion and chloride ion products. The fluorine atoms in the fluoride dissociate and form fluorine ions as products.
The aluminum in the alum dissociates into aluminum ions. The electrons from the oxide ion form an electron system, or an electrose. The selenium in the sulfide does not dissociate, so it remains as a product.
This is interesting because it shows how some elements do not react with hydrofluoric acid, while others do. All of these products play a role in determining the color of the solution that is formed after this reaction occurs.
For example, if there were no aluminum ions or no oxide ions in the solution, then it would be colorless. If there was only one of these compounds present, then only one of those colors would be shown.
Identify the species
The next step is to identify the species involved in the reaction. This is important because it determines what compounds can be produced in the reaction.
Sn(s) can be reduced to Sn(s)2- or Sn(l) by reacting with a reducing agent. A reducing agent is a molecule that has at least one electron available to transfer to another molecule.
Sn(s)2- can then be reacted with three Fe(s) ions to produce three FeSn2(s)- ions, which is linseed oil. Linseed oil has many uses, such as being a protective coating or cooking medium.
In this experiment, we will not be producing any Sn(l) or Sn2- due to the fact that we are using NaBH4 as our reducing agent.
Assign oxidation states
In this equation, sulfide has an oxidation state of -2. This is because there are two sulfur atoms that each have an electron in them, so they need to be paired with two iron atoms.
Since there are six iron atoms, each sulfide needs to be paired with two iron atoms, making the oxidation state of sulfide -2. Iron(II) has an oxidation state of +2, so the total oxidation state of the Fe in this reaction is +4.
Sodium has an oxidation state of +1, and oxygen has an oxidation state of -2. Since there is only one sodium atom and one oxygen atom in the reactant side, these do not need to be accounted for in the final product ratio.
The reactants do not have a net charge, so you do not have to worry about charging the products. The products are at zero charge.
Match species to formulas
A species is a set of atoms with the same atomic number and, usually, the same chemical properties. For example, hydrogen is a species; all atoms of hydrogen have 1 proton and they all behave similarly.
When you are given a formula for a compound, you must determine what species are included in the formula. This is an important step when determining what reactions a compound will undergo.
In the above reaction, we can see that there are three elements present: iron (Fe), sodium (Na), and sulfur (S). Therefore, the formula we want for this reaction is Fe(s)+3Na+(aq)→2Fe(s)Na+(aq).
You can check this by adding the Na+ in at the end and seeing if the solution changes color.
Assign Charges (+ or -)
Once you have determined what atoms are in the molecule, you must assign a charge to each atom. This is typically assigned based on the period table row the element comes from.
For example, sodium (Na) comes from the Group 1 column, and hydrogen (H) comes from the leftmost column of the Periodic Table. By convention, charges are assigned such that Group 1 elements have a +1 charge, and leftmost column elements have a -1 charge.
Other conventions exist, so make sure you check with your professor to make sure which one they require you to use!
Some molecules contain atoms of different charges within them. By convention, molecules containing an ionized atom with a negative charge are given a positive countercharge of equivalent magnitude. Ionized atoms with a positive charge are given an equivalent negative countercharge.
Solve for final charge on each ion using a quadratic equation and determine if there is a complex formation reaction
Once you have determined the total charge on the ions, you can then determine what type of reaction has occurred.
If the total charge on the ions is negative, then a dissolution reaction has occurred. If the total charge on the ions is positive, then a complex formation reaction has occurred.
Dissolution reactions occur when a single ion enters a solution and loses or gains an electron(s) to become another ion. These are also called electrophilic reactions as the reacting ion accepts an electron.
For example, if an iron(II) ion enters a solution it will dissolve and form an iron(III) ion. This is because it accepts an electron to become more negatively charged.
In complex formation reactions, an already formed complex (ion pair) dissociates and re-forms as two separate ions with different charges. For example, if an iron(III) oxide (rust) dissociates into an iron(III) and oxygen ion, it forms a complex formation reaction.
Write the balanced chemical equation
Next, you will write the chemical equation for this reaction. The chemical equation lists the types of atoms and how many of each atom are present in the reaction solution.
In this case, you would write:
2fe3+(aq)+3sn(s)→2fe(s)+3sn2+(aq)
This tells us that two ferrous ions combine with three tin ions and produce silver sulfide and sodium ions. The sodium ion is not involved in this reaction, it is only listed as a product.
Check your work by comparing your equation to the balanced chemical equation for this reaction.
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