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DerKrebs [107]
3 years ago
13

Distillation is a process of vaporization a substance and chilling the vapor to collect it back the liquid form. How much heat i

s removed from 74.2 grams of ethanol vapor at 83 °C (Tb = 78.37 °C) if the collected liquid ethanol has a temperature of 26ºC?
Chemistry
1 answer:
stich3 [128]3 years ago
3 0

Answer:

72 kJ of heat is removed.

Explanation:

First, the ethanol vapor will reduce its temperature until the temperature of the boiling point, then it will occur a phase change from vapor to liquid, and then the temperature of the liquid will decrease. The total heat will be:

Q = Q1 + Q2 + Q3

Q1 = n*cv*ΔT1, Q2 = m*Hl, and Q3 = n*cl*ΔT2

Where n is the number of moles, cv is the specific heat of the vapor (65.44 J/K.mol, cl is the specific heat of the liquid (111.46 J/K.mol), Hl is the heat of liquefaction (-836.8 J/g), m is the mass, and ΔT is the temperature variation (final - initial).

Q = n*cv*ΔT1 + m*Hl + n*cl*ΔT2

The molar mass of ethanol is 46 g/mol, and the number of moles is the mass divided by the molar mass:

n = 74.2/46 = 1.613 moles

Q = 1.613*65.44*(78.37 - 83) + 74.2*(-836.8) + 1.613*111.46*(26 - 78.37)

Q = -72000 J

Q = -72 kJ (because it is negative, it is removed)

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The normal boiling point of iodomethane, CH3I, is 42.43 8C, and its vapor pressure at 0.00 8C is 140. Torr. Calculate (a) the st
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Answer:

a=28600J; b=90.6 J/K; c=402 torr

Explanation:

(a) considering the data given

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Using the Clausius-Clapeyron Equation

ln (P2/P1) = (ΔH/R)(1/T2 - 1/T1)

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The chemical symbol of sodium is Na. It is located in the group (colum) 1 and period (raw) 3. There you find that the atomic number is 11. Hence your drawing must show 11 protons.

Since the atom is neutral, the number of electrons is also 11. So, you must place the electrons in the following energy levels or shells:

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