The principle is that iodine is liberated by adding sulphuric acid to a solution of iodised salt. Potassium iodide solution is added to keep the iodine in the dissolved state. Iodine liberated is titrated with sodium thiosulphate solution to form sodium iodide and sodium tetrathionate.
- 1 What is the principle of iodometric titration?
- 2 How does an iodine titration work?
- 3 Why do we use iodometric titration?
- 4 Why is iodine solution unstable?
- 5 Why is sodium thiosulfate used in iodometric titration?
- 6 How is iodine solution prepared in the laboratory?
- 7 Why iodometric titrations are done in dark?
- 8 Why is iodine a strong reducing agent?
- 9 What are the differences between weak and strong iodine solution?
- 10 Is iodine brittle or malleable?
- 11 What is iodine malleability?
- 12 Is iodine good conductor of electricity?
- 13 Does iodine lose or gain electrons?
- 14 How many electrons does iodine need to gain or lose to become stable?
- 15 What charge does iodine have when it becomes an ion?
- 16 Why is iodine a anion?
- 17 How is iodine converted to iodide?
- 18 Is iodine corrosive to metal?
- 19 Why are iodine oxides more stable?
- 20 Why is iodide more stable than chloride?
- 21 Which is more stable fluorine or iodine?
- 22 Why does the halide stability decrease down the group?
- 23 Which halide is most stable?
- 24 Why hexafluoride are only stable halides?
What is the principle of iodometric titration?
The Basic Principle of iodometric titration is to determine the concentration of an oxidising agent in solution. iodometry involves indirect titration of iodine liberated by reaction with the analyte.In an iodometric titration, a starch solution is used as an indicator since it can absorb the I2 that is released.
How does an iodine titration work?
As the iodine is added during the titration, the ascorbic acid is oxidised to dehydroascorbic acid, while the iodine is reduced to iodide ions. Due to this reaction, the iodine formed is immediately reduced to iodide as long as there is any ascorbic acid present.
Why do we use iodometric titration?
Iodometric methods can be used for the quantitative determination of strong oxidizing agents such as potassium dichromate, permanganate, hydrogen peroxide, cupric ion and oxygen. As has been mentioned above, the endpoint in a titration of iodine with thiosulfate is signaled by the color change of the starch indicator.
Why is iodine solution unstable?
Iodine is very weakly soluble in the water, and can be easily lost from the solution due to its volatility. However, in the presence of excess iodides iodine creates I3– ions. This lowers free iodine concentration and such solutions are stable enough to be used in lab practice.
Why is sodium thiosulfate used in iodometric titration?
Iodometry is used to determine the concentration of oxidizing agents through an indirect process involving iodine as a mediator. In the presence of iodine, thiosulphate ions are quantitatively oxidized to tetrathionate ions.
How is iodine solution prepared in the laboratory?
Dissolve KI in about 20-30 ml of distilled water. Add iodine and heat gently with constant mixing until iodine is dissolved. Dilute to 100 ml with distilled water. Store in amber glass-stoppered bottle in the dark.
Why iodometric titrations are done in dark?
The reaction mixture should be kept in the dark before titration because light accelerates a side reaction in which iodide ions are oxidized to iodine by atmospheric oxygen.
Why is iodine a strong reducing agent?
The iodide ion is a strong reducing agent; that is, it readily gives up one electron. Although the iodide ion is colourless, iodide solutions may acquire a brownish tint as a result of oxidation of iodide to free iodine by atmospheric oxygen.
What are the differences between weak and strong iodine solution?
Aqueous iodine solutions do not contain any alcohol. Strong iodine solution contains alcohol. Weak iodine solutions do not contain alcohol.
Is iodine brittle or malleable?
Iodine has the highest melting and boiling points of the halogens. This is caused by iodine’s relatively large size which results in the strongest van der Waals interactions between the molecules of iodine. Like many nonmetals, solid iodine is very brittle (the opposite of ductile).
What is iodine malleability?
Explanation: Malleability, the ability of a material to be hammered out into a sheet (from the Latin, malleus, hammer , is a fundamental property of metals. Solid non-metals, e.g. diamond, sulfur, iodine, do not tend to have this property.
Is iodine good conductor of electricity?
Non-metals are the bad conductor of electricity except one i.e Graphite(made of carbon). Hence iodine,sulphur and bromine do not conduct electricity.
Does iodine lose or gain electrons?
Iodine is more likely to gain one electron. It will become I− ion.
How many electrons does iodine need to gain or lose to become stable?
The iodine atom also changes when it combines to form potassium iodide. An iodine atom has seven electrons in its outer energy level. A stable outer energy level has eight electrons. When the iodine atom reacts with the potassium atom, the iodine atom gains one electron from potassium.
What charge does iodine have when it becomes an ion?
Answer and Explanation: The element iodine will exist as an anion with a charge of -1.
Why is iodine a anion?
Iodide salts are mild reducing agents and many react with oxygen to give iodine. Iodide is a halide anion and a monoatomic iodine. It has a role as a human metabolite. It is a conjugate base of a hydrogen iodide.
How is iodine converted to iodide?
Add 1.5 mL of concentrated hydrochloric acid (or about 1.8 mL of hardware store muriatic acid) to the test tube and swirl to mix the solutions. Add about 10 mL of drugstore 3% hydrogen peroxide. The solution immediately turns dark brown as the iodide ions are oxidized to elemental iodine, which precipitates out.
Is iodine corrosive to metal?
Iodine reacts violently or explosively with ACETYLENE; ACETALDEHYDE; METAL AZIDES; METAL HYDRIDES; and METAL CARBIDES. Iodine forms explosive or shock-sensitive compounds when mixed with REDUCING AGENTS (such as LITHIUM, SODIUM, ALUMINUM and their HYDRIDES) and liquid AMMONIA.
Why are iodine oxides more stable?
The stability of oxides of iodine is greater than those of chlorine while bromine oxides are the least stable. Iodine-oxygen bond is stable due to greater polarity of the bond while the stability of the chlorine-oxygen bond is due to multiple bond formation involving d-orbitals of the chlorine atom.
Why is iodide more stable than chloride?
My textbook says that HI is a stronger acid than HCl because Iodide ion is more stable than Chloride ion due to the bigger size of Iodine. But the electron affinity of Chlorine is -347J while the electron affinity of Iodine is -295J.
Which is more stable fluorine or iodine?
Generally, the ease of oxidation increases as the atomic number increases for the halogens. Fluoride being the most stable to oxidation and iodide being rather easy to oxidize.
Why does the halide stability decrease down the group?
As we go down the group, ionic radius increases and so, the bond length of metal halide also increases. Due to the longer bond length, stability of halides decreases.
Which halide is most stable?
Stability of carbon tetrahalides decreases with increase in the size of halogen atom. So, CF4 is the most stable halide among the given options.
Why hexafluoride are only stable halides?
Among hexa halides, only hexa fluorides are stable because of the small size of fluorine. Fluorine is very small in size, as a result of which six fluorine atoms can be easily accommodated around the central atom.