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What is the mechanism of DNPH react with acetone?
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Kaori Kitao
What is the mechanism of DNPH react with acetone?
The mechanism of the reaction between 2,4-dinitrophenylhydrazine (DNPH) and acetone to form a hydrazone is PADPED: Protonation, Addition, Deprotonation, Protonation, Elimination, Deprotonation. This applies to formation of imines, oximes and hydrazones. You can read the details here.
Note that I have no connection, monetary or otherwise, with the linked site, I am simply passing it on to you as a source of accurate scientific information. Quora moderation – valid information is not spam.
The mechanism of the reaction between 2,4-dinitrophenylhydrazine (DNPH) and acetone to form a hydrazone is PADPED: Protonation, Addition, Deprotonation, Protonation, Elimination, Deprotonation. This applies to formation of imines, oximes and hydrazones. You can read the details here.
Note that I have no connection, monetary or otherwise, with the linked site, I am simply passing it on to you as a source of accurate scientific information. Quora moderation – valid information is not spam.
Well, there may be something wrong with the question. There are two ways to solve this question. The first, and the way at least 2 others have responded, is with the ideal gas law. OK, so we will go that way, first. The ideal gas law is
PV=nRT
and we want to know n, the number of moles, so
n = PV/RT
P is pressure in atm (here = 1.02 atm), V = volume in liters (here, 0.055 L), T is temperature in K (here, 358 K), and R is a constant, 0.0821. Putting in the numbers and solving gives
n = (1.02)(0.055)/((0.0821)(358)) = 0.00191 moles of acetone.
Now, it seems to me, that there is a second way to do this problem, and perhaps easier. The question states that the vapor weighs 7.23 g. Now, if the vapor is only acetone then given the molecular mass of acetone (58 g/mol) then we should be able to just divide the mass of the vapor by the molar mass of acetone to get the number of moles.
n = 7.23 g / 58 g/mol = 0.125 mol
Given the values for P, V, T I am inclined to believe the ideal gas law result and assume that someone made a mistake weighing.
Someone might say the flask was not evacuated when the acetone was put in the flask so it already had a gas in it and the weight of the vapor is the acetone + gas, but, if so, this would have an effect on the first calculation because ’n’ would refer to the number of moles of all gases, not just acetone. If so, then the answer calculated by the ideal gas is wrong.
Well, there may be something wrong with the question. There are two ways to solve this question. The first, and the way at least 2 others have responded, is with the ideal gas law. OK, so we will go that way, first. The ideal gas law is
PV=nRT
and we want to know n, the number of moles, so
n = PV/RT
P is pressure in atm (here = 1.02 atm), V = volume in liters (here, 0.055 L), T is temperature in K (here, 358 K), and R is a constant, 0.0821. Putting in the numbers and solving gives
n = (1.02)(0.055)/((0.0821)(358)) = 0.00191 moles of acetone.
Now, it seems to me, that there is a second way to do this problem, and perhaps easier. The question states that the vapor weighs 7.23 g. Now, if the vapor is only acetone then given the molecular mass of acetone (58 g/mol) then we should be able to just divide the mass of the vapor by the molar mass of acetone to get the number of moles.
n = 7.23 g / 58 g/mol = 0.125 mol
Given the values for P, V, T I am inclined to believe the ideal gas law result and assume that someone made a mistake weighing.
Someone might say the flask was not evacuated when the acetone was put in the flask so it already had a gas in it and the weight of the vapor is the acetone + gas, but, if so, this would have an effect on the first calculation because ’n’ would refer to the number of moles of all gases, not just acetone. If so, then the answer calculated by the ideal gas is wrong.
The mechanism of the reaction between 2,4-dinitrophenylhydrazine (DNPH) and acetone to form a hydrazone is PADPED: Protonation, Addition, Deprotonation, Protonation, Elimination, Deprotonation. This applies to formation of imines, oximes and hydrazones. You can read the details here.
Note that I have no connection, monetary or otherwise, with the linked site, I am simply passing it on to you as a source of accurate scientific information. Quora moderation – valid information is not spam.
The mechanism of the reaction between 2,4-dinitrophenylhydrazine (DNPH) and acetone to form a hydrazone is PADPED: Protonation, Addition, Deprotonation, Protonation, Elimination, Deprotonation. This applies to formation of imines, oximes and hydrazones. You can read the details here.
Note that I have no connection, monetary or otherwise, with the linked site, I am simply passing it on to you as a source of accurate scientific information. Quora moderation – valid information is not spam.
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Well, there may be something wrong with the question. There are two ways to solve this question. The first, and the way at least 2 others have responded, is with the ideal gas law. OK, so we will go that way, first. The ideal gas law is
PV=nRT
and we want to know n, the number of moles, so
n = PV/RT
P is pressure in atm (here = 1.02 atm), V = volume in liters (here, 0.055 L), T is temperature in K (here, 358 K), and R is a constant, 0.0821. Putting in the numbers and solving gives
n = (1.02)(0.055)/((0.0821)(358)) = 0.00191 moles of acetone.
Now, it seems to me, that there is a second way to do this problem, and perhaps easier. The question states that the vapor weighs 7.23 g. Now, if the vapor is only acetone then given the molecular mass of acetone (58 g/mol) then we should be able to just divide the mass of the vapor by the molar mass of acetone to get the number of moles.
n = 7.23 g / 58 g/mol = 0.125 mol
Given the values for P, V, T I am inclined to believe the ideal gas law result and assume that someone made a mistake weighing.
Someone might say the flask was not evacuated when the acetone was put in the flask so it already had a gas in it and the weight of the vapor is the acetone + gas, but, if so, this would have an effect on the first calculation because ’n’ would refer to the number of moles of all gases, not just acetone. If so, then the answer calculated by the ideal gas is wrong.
Something is wrong with the question, I think.
Well, there may be something wrong with the question. There are two ways to solve this question. The first, and the way at least 2 others have responded, is with the ideal gas law. OK, so we will go that way, first. The ideal gas law is
PV=nRT
and we want to know n, the number of moles, so
n = PV/RT
P is pressure in atm (here = 1.02 atm), V = volume in liters (here, 0.055 L), T is temperature in K (here, 358 K), and R is a constant, 0.0821. Putting in the numbers and solving gives
n = (1.02)(0.055)/((0.0821)(358)) = 0.00191 moles of acetone.
Now, it seems to me, that there is a second way to do this problem, and perhaps easier. The question states that the vapor weighs 7.23 g. Now, if the vapor is only acetone then given the molecular mass of acetone (58 g/mol) then we should be able to just divide the mass of the vapor by the molar mass of acetone to get the number of moles.
n = 7.23 g / 58 g/mol = 0.125 mol
Given the values for P, V, T I am inclined to believe the ideal gas law result and assume that someone made a mistake weighing.
Someone might say the flask was not evacuated when the acetone was put in the flask so it already had a gas in it and the weight of the vapor is the acetone + gas, but, if so, this would have an effect on the first calculation because ’n’ would refer to the number of moles of all gases, not just acetone. If so, then the answer calculated by the ideal gas is wrong.
Something is wrong with the question, I think.
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