Question

How much energy is required to vaporize 98.6 g of ethanol (C2H5OH) at its boiling point, if its ΔHvap is 40.5 kJ/mol? How much energy is required to vaporize 98.6 g of ethanol (C2H5OH) at its boiling point, if its ΔHvap is 40.5 kJ/mol? 52.8 kJ 11.5 kJ 86.7 kJ 39.9 kJ 18.9 kJ

Answer 1

86.7 kJ

Further explanation

Given:

Molar mass (Mr) of ethanol = 46.07 g/mol

$\Delta H_{vap} \ C_2H_5OH = 40.5 \ kJ/mol$

Question:

How much energy is required to vaporize 98.6 g of ethanol (C₂H₅OH) at its boiling point?

The Process:

Observe this $\Delta H_{vap} \ C_2H_5OH = 40.5 \ kJ/mol$. This means that 40.5 kJ of energy is required to vaporize every 1 mole of ethanol at its boiling point. Therefore we must first convert grams into moles.

Question:

Step-1:

Let us count the number of moles of 98.6 g of ethanol.

$\boxed{moles \ (n) = \frac{mass}{Mr}}$

$\boxed{moles \ (n) = \frac{98.6 \ g}{46.07 \ g/mol}}$

We obtain 2.14 moles of ethanol.

Step-2:

Let us calculate how much energy is required to vaporize 2.14 moles of ethanol at its boiling point.

The amount of energy required is $\boxed{n \times \Delta H_{vap}}$

$\boxed{ \ The \ energy = 2.14 \ moles \times 40.5 \ \frac{kJ}{mol} \ }$

$\boxed{ \ The \ energy = 86.67 \ kJ \approx 86.7 \ kJ \ }$

Thus, the amount of energy required to vaporize 98.6 g of ethanol at its boiling point is 86.7 kJ.

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Quick Steps

$\boxed{ \ The \ energy \ required = 98.6 \ g \times \frac{1 \ mol}{46.07 \ g} \times 40.5 \ \frac{kJ}{mol} \approx 86.7 \ kJ \ }$

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Keywords: how much, energy required, to vaporize, ethanol, C₂H₅OH, its boiling point, ΔHvap, molar mass, moles, converts, kJ/mol

Answer 2

Answer:

The amount of energy required will be 86.7 kJ.

Explanation:

Mass of ethanol = 98.6 g

Moles of ethanol = $\frac{98 g}{46 g/mol}=2.1434 moles$

Enthalpy of vaporization of ethanol =$\Delta H_{vap}=40.5 kJ/mol$

To vaporize 1 mol of ethanol we need 40.5 kJ of energy.

Then for 2.1434 moles the energy required will be:

$40.5 kJ\times 2.1432 kJ=86.79 kJ$

The closest answer from the given options is 86.7 kJ.