Its chemistry, appearance, and behaviour are very similar to those of the more widely encountered potassium dichromate. The hazard fields include special hazard alerts air and water reactions, fire hazards, health hazards, a reactivity profile, and details about reactive groups assignments and potentially incompatible absorbents. Equivalent weight of potassium dichromate molecular mass6 294,1856 49,0308. Stable under normal temperature and pressure, potassium dichromate is in no way. Potassium dichromate potentiometric titration of iron in. What is gram equivalent weight of potassium dichromate. What is the equivalent mass of potassium dichromate. Potassium dichromate, k 2cr 2o 7, is a common inorganic chemical reagent, most commonly used as an oxidizing agent in various laboratory and industrial. Estimate the equivalent weight of potassium dichromate in acidic. The equivalent weight of k2cr2o7 in acidic medium is.
Equivalent weight of substances required in volumetric analysis on globalspec. Aug 09, 2009 hexavalent chromium compounds the form present in the dichromate ion are carcinogenic, and this fact should be considered when evaluating potassium dichromate against other oxidizers such as ceric sulfate, potassium iodate and potassium permanganate. It is a strong oxidising agent and is highly corrosive. A specific weight of the compound is titrated with a known concentration of acid or base until the equivalence point has been reached. Mar 16, 2010 i would like to know the change in oxidation number for k2cr2o7 in order to calculate its equivalent weight. Potassium dichromate formula is k2cr2o7 and its formula becomes 294.
Potassium dichromate is commonly used in acid solution to standardize ferrous salt solutions using ferroin indicator. If the formula used in calculating molar mass is the molecular formula, the formula weight computed is the molecular weight. Potassium dichromate is a versatile, powerful oxidizing agent although not as powerful as. The gram equivalent weight of potassium dichromate is 149. Equivalent weight, in chemistry, the quantity of a substance that exactly reacts. Eye contact rinse immediately with plenty of water, also under the eyelids, for at least 15 minutes.
What is the equivalent mass of potassium dichromatek2cr2o7. Potassium dichromate, k 2 cr 2 o 7, is a common inorganic chemical reagent, most commonly used as an oxidizing agent in various laboratory and industrial applications. For a redox reaction, equivalent weight molecular weight. The equivalent weight is the gram molecular weight divided by the number of electrons lost or gained by each molecule. Mar 26, 2018 for a redox reaction, equivalent weight molecular weight. Refer to the definition of equivalent iupac gold book. The iodine formed in the reaction oxidizes sodium thiosulphate giving sodium tetrathionate ion and the end point is detected by starch solution. Mass is the amount of matter in something, while weight is the gravitational pull on a mass. From the volume and concentration of added acid or base and the initial weight of the compound, the equivalent weight, and thus the number of. Sodium dicromate produces toxic chromium vapours when heated. The blood sample was analyzed to assess oxidative stress and cellular damage. From the half reaction for dichromate it can be seen that one mole of dichromate ion requires six moles of electrons. Titration and substances used chemical formula equivalent weight acidalkali titration sodium carbonate washing soda na 2co 3 m.
Potassium dichromate formula potassium dichromate uses. Mice in group b and c received potassium dichromate and magnesium sulfate of 5. The percentage by weight of any atom or group of atoms in a compound can be computed by dividing the total weight of the atom or group of atoms in the formula by the formula weight and multiplying by 100. It is a crystalline ionic solid with a very bright, redorange color. Potassium dichromate formula is k2cr2o7 and its formula weight is 294. The formula to calculate equivalent weight is as follows. Potassium dichromate is a versatile, powerful oxidizing agent although not as powerful as potassium permanganate that also meets the requirements of being a primary standard. The sodium salt is, however, around twenty times more soluble in water than the potassium salt 49 gl at 0 c and its equivalent weight is also lower, which is often desirable. Therefore, the equivalent weight of k2cr2o7 is 294. Hexavalent chromium compounds the form present in the dichromate ion are carcinogenic, and this fact should be considered when evaluating potassium dichromate against other oxidizers such as ceric sulfate, potassium iodate and potassium permanganate. The burette was rinsed with potassium dichromate solution and was filled up to zero mark.
The chromate ion is the predominant species in alkaline solutions, but dichromate can become the predominant ion in acidic solutions. Convert grams potassium dichromate to moles or moles potassium dichromate to grams. It is a strong oxidizing agent and is highly corrosive. Component casno weight % potassium dichromate 7778509 95 4.
How to prepare potassium dichromate to calculate the chemical. Sodium dichromate is similar to potassium dichromate, especially in its reactivity and physical features, however, the sodium salt is more soluble in water and its equivalent weight is less. The equivalent weight of potassium dichromate is the ratio molar mass change in the oxidation number. How to calculate equivalent weight of potassium dichromate quora. K2cr2o7 potassium dichromate ii oxidation state, colour. From this equation it follows that the equivalent weight of potassium dichromate is 16th of the molecular weight i. Potassium dichromate in acidic medium is a strong oxidizer.
Thus, potassium permanganate reacting by double decomposition has an equivalent weight equal to its gram molecular weight, 158. One equivalent of oxygen is 162 or 8 grams which means that the consumption of 6. Potassium dichromate in acidic solution results in. Mohrs salt solution using potassium dichromate k 2 cr 2 o 7 solution as an intermediate solution provided with a known. Molecular weight of potassium dichromate convert units. How to prepare potassium dichromate to calculate the. Sodium dichromate produces toxic fumes of chromium when heated. Potassium dichromate is used to standardize sodium thiosulfate solutions. Potassium dichromate k2cr2o7 or cr2k2o7 cid 24502 structure. In the standardization of na2s2o3 using k2cr2o7 by. Potassium dichromate titration of iron in natural magmas. The information in cameo chemicals comes from a variety of data sources. What is gram equivalent weight of potassium dichromate answers. The aim was to gather sufficient information and data to enable a thorough comparison with the baseline and ultimately, to advise on the best method to employ for future effluent water testing.
Equivalent weights may be calculated from molar masses if the chemistry of the substance is well known. In acidic solution, potassium dichromate oxidizes potassium iodide to iodine. If we look at the defining ratio of equivalent weight of a compound ab formed of two radicals say a and b, then we can rearrange the ratio as. Potassium dichromate is highly corrosive and is a strong oxidizing agent. If the equivalent weight of potassium dichromate is. In terms of reactivity and appearance, sodium dichromate has properties similar to potassium dichromate, however, the sodium salt is more soluble in water and has a lower equivalent weight to the potassium salt. In the standardisation of n2s2o3 using k2cr2o7 by iodometry.
The concept of equivalent weight allows you to explore the fact that atoms combine to form molecules in fixed number ratios, not mass ratios. Equivalent weight, in chemistry, the quantity of a substance that exactly reacts with, or is equal to the combining value of, an arbitrarily fixed quantity of another substance in a particular reaction. Results showed high malondialdehyde mda and low levels of antioxidant enzymes catalase cat. It can be achieved by following these steps, namely. In the standardization of na2s2o3 using k2cr2o7 by iodometry.
How to calculate equivalent weight of potassium dichromate. In aqueous solution, chromate and dichromate anions exist in a chemical equilibrium 2 cro 2. From the volume and concentration of added acid or base and the initial weight of the compound, the equivalent weight, and thus the number of acidic or basic groups, can be computed. Potassium dichromate is commonly used in acid solution to standardize ferrous salt solutions using ferroin. That is, while element masses differ, when it comes to bonding with other atoms, the number of atoms, expressed in moles, is the determining factor in how much of a given element or compound will react with a given mass of another. The dichromate ion is a somewhat weaker base than the chromate ion.
The molar mass of potassium permanganate is 158 gmol. The chemical formula for potassium dichromate is k 2 cr 2 o 7 and its molar mass is 294. Preparation and standardization of sodium thiosulphate labmonk. Firstaid measures general advice show this safety data sheet to the doctor in attendance. Aug 18, 2010 the equivalent weight is the gram molecular weight divided by the number of electrons lost or gained by each molecule. Equivalent weight is the mass of the substance that combines with a fixed quantity of another substance. To determine the strength in gl of the given unknown strength ferrous ammonium sulphate feso 4. Substances react with each other in stoichiometric, or chemically equivalent, proportions, and a. As with all hexavalent chromium compounds, it is acutely and chronically harmful to health. Jan 16, 2018 potassium dichromate in acidic medium is a strong oxidizer.
Hence, based on the above theory our aim is to prepare and standardize sodium thiosulphate using potassium. Potassium dichromate oxidizes the iodide ion in acidic medium to equivalent amount of iodine. Potassium dichromate has a melting point of 398 degrees celsius and molecular weight of 294. The predominance diagram shows that the position of the equilibrium depends on both ph and the analytical concentration of chromium. Estimate the equivalent weight of potassium dichromate in acidic medium.
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