dimethylglyoxime is used as a reagent in qualitative analysis to precipitate the nickel(II) ion. a solution is made by dissolving 57.0 grams of DMG in 430.0 g of ethanol.
(a) what is the mole fraction of DMG in this solution?
(b) what is the molality of this solution?
(c) what is the vapor pressure over the solution at ethanol's normal boiling point, 78.4 degrees Celsius?
(d) what is the boiling point of this solution (DMG does not dissociate)? Kb (ethanol) = +1.22 degrees celsius/m
A long series of questions. Have you thought about any of it. How much do you know how to do? What is your biggest hurdle to working the problems?
To solve these problems, we need to use the given information and apply some relevant formulas. Let's break down each question step by step:
(a) To find the mole fraction of DMG in the solution, we need to calculate the moles of DMG and moles of ethanol separately.
First, we calculate the moles of DMG:
Mass of DMG = 57.0 grams
Molar mass of DMG = 79.1 g/mol
Moles of DMG = Mass of DMG / Molar mass of DMG
Next, we calculate the moles of ethanol:
Mass of ethanol = 430.0 grams
Molar mass of ethanol = 46.07 g/mol
Moles of ethanol = Mass of ethanol / Molar mass of ethanol
Finally, we can find the mole fraction of DMG:
Mole fraction of DMG = Moles of DMG / (Moles of DMG + Moles of ethanol)
(b) To find the molality of the solution, we need to use the same values of moles calculated above and divide it by the mass of the solvent (ethanol) in kilograms.
Molality = Moles of DMG / Mass of ethanol (in kg)
(c) To find the vapor pressure over the solution at ethanol's normal boiling point, we need to use Raoult's law. According to Raoult's law, the vapor pressure of a component in an ideal solution is equal to its mole fraction multiplied by its vapor pressure in its pure form.
Vapor pressure over the solution = Mole fraction of ethanol * Vapor pressure of ethanol (at the normal boiling point)
(d) To find the boiling point elevation, we need to use the formula:
ΔT = Kb * molality
where ΔT is the boiling point elevation, Kb is the molal boiling point constant of the solvent (ethanol), and molality is the molality of the solution calculated in part (b).
Boiling point of the solution = Boiling point of pure ethanol + ΔT
By substituting the values into the formulas, you can calculate the answers for each part of the question. Remember to convert units when necessary.