Since molecules of potassium contain only single potassium atoms, molecules of iodine contain two atoms, and moles of potassium iodide contain one atom of each element, 2.5 moles of iodine are needed to react completely with 5 moles of potassium.
It sounds like you're describing Lugol's iodine. It's not technically "required," it's just that's what the recipe is. Actually, in Lugol's iodine, KI is needed to improve the dissolution of iodine in water.
Iodometric titration means the titration of triiodide. Preparation of triiodide can be prepared by adding solid iodine to excess potassium iodide, however since iodine sublimes it is more difficult to weigh than potassium iodate. The triiodide would then need to be standardized with primary standard grade arsenious oxide. A better way is to weigh potassium iodate and add to a small excess of potassium iodide. The two ions (iodide and iodate) will also form the needed triiodide in an acidic environment. If the reagent is made fresh this way it can be used to standardize thiosulfate. Iodide iodate of known normality can also be used to titrate unknown concentrations of sulfite. For example, steam boiler treatment applications.
Potassium iodide has a high melting point because of its strong ionic bonds between potassium and iodine atoms. To overcome these bonds and separate the ions, a high temperature is required to provide enough energy to break the bonds and transition the solid to a liquid state.
One atom of potassium will react with one atom of iodine according to the balanced chemical equation for the reaction between potassium and iodine: 2K + I2 → 2KI.
To find the number of moles of potassium iodide needed, multiply the volume of the solution (750 ml) by the molarity (1.8 moles/L). First, convert the volume to liters (750 ml = 0.75 L), then multiply 0.75 L by 1.8 moles/L to get 1.35 moles of potassium iodide.
It sounds like you're describing Lugol's iodine. It's not technically "required," it's just that's what the recipe is. Actually, in Lugol's iodine, KI is needed to improve the dissolution of iodine in water.
The leaf was rinsed in water to rehydrate it. Iodine solution is an aqueous solution of iodine/potassium iodine - potassium tri-iodide; water is needed inside the leaf to enable penetration by diffusion.
- The atomic weight of iodine is 126,90447; for a 0,1 N solution, dividing by 10 the result is 12,69. - The iodide (KI) is added to increase the solubility of iodine in water or alcohol.
Potassium is K1+, and Iodine is I1-. As a result, Potassium iodide is made. It's ionic becuase Potassium has a positive charge, so it needs one more electron to have its orbitals filled. Iodine on the other hand, has an electron that isn't needed. If Iodine can give up its electron, then all of its orbitals will be filled. As a result, iodine gives it's extra electron to the potassium, and they both have filled orbitals. When an electron is being given and accepted, that's called an ionic bond. So Potassium iodide is ionic.
Iodized salt is a combination of regular table salt, sodium chloride, with a small amount of a salt of iodine, potassium iodide. Iodized salt has gained popularity in some countries because iodine is needed by the thyroid to function properly and iodine deficiency can cause the thyroid disease called goiter.
Iodometric titration means the titration of triiodide. Preparation of triiodide can be prepared by adding solid iodine to excess potassium iodide, however since iodine sublimes it is more difficult to weigh than potassium iodate. The triiodide would then need to be standardized with primary standard grade arsenious oxide. A better way is to weigh potassium iodate and add to a small excess of potassium iodide. The two ions (iodide and iodate) will also form the needed triiodide in an acidic environment. If the reagent is made fresh this way it can be used to standardize thiosulfate. Iodide iodate of known normality can also be used to titrate unknown concentrations of sulfite. For example, steam boiler treatment applications.
530,3 g potassium iodide are needed.
Potassium iodide has a high melting point because of its strong ionic bonds between potassium and iodine atoms. To overcome these bonds and separate the ions, a high temperature is required to provide enough energy to break the bonds and transition the solid to a liquid state.
The amount of excess potassium iodide depends on the stoichiometry of the reaction between potassium iodide and copper sulfate. One equivalent of potassium iodide is needed to react with one equivalent of copper sulfate. Excess potassium iodide would be any amount added beyond this stoichiometric ratio.
KF has small size than KCl. So the packing of atoms / ions in KF is more than that in KCl. So a larger energy is needed to separate the atoms from solid state to liquid state and hence KF has higher melting point than KCl.
One atom of potassium will react with one atom of iodine according to the balanced chemical equation for the reaction between potassium and iodine: 2K + I2 → 2KI.
A barium ion has a charge of 2+ and an iodide ion has a charge of 1-, therefore, two iodide ions are needed to balance the barium ion. Ba2+ + 2I- --> BaI2