Ethanol, C2 H5 OH, boils at 78.29^∘ C . How much energy, in joules, is required to raise the tem

Ethanol, C2 H5 OH, boils at 78.29^∘ C . How much energy, in...

Ethanol, $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH},$ boils at $78.29^{\circ} \mathrm{C} .$ How much energy, in joules, is required to raise the temperature of $1.00 \mathrm{kg}$ of ethanol from $20.0^{\circ} \mathrm{C}$ to the boiling point and then to change the liquid to vapor at that temperature? (The specific heat capacity of liquid ethanol is $2.44 \mathrm{J} / \mathrm{g} \cdot \mathrm{K},$ and its enthalpy of vaporization is $855 \mathrm{J} / \mathrm{g} .$ )

Key Concepts

Specific Heat Capacity

Specific heat capacity is a property of a substance that indicates the amount of energy required to raise the temperature of a unit mass of the substance by one degree Celsius (or one Kelvin). It is a key concept in thermal physics and is used to calculate the sensible heat needed to change the temperature of a substance without changing its phase.

Enthalpy of Vaporization

Enthalpy of vaporization is the amount of energy required to convert a unit mass of a liquid into vapor at its boiling point without a temperature change. This concept is crucial in understanding phase transitions and is particularly important in processes involving boiling, distillation, and evaporation.

Temperature Change

Temperature change refers to the difference between the final and initial temperatures of a substance. In thermal calculations, this difference is used in conjunction with the specific heat capacity to determine the total energy required to change the substance's temperature.

Unit Conversion

Unit conversion is the process of converting measurements from one unit system to another to ensure consistency in calculations. In thermodynamic problems, converting masses (e.g., kilograms to grams) is often necessary because the given material properties, such as specific heat capacity or enthalpy of vaporization, may be expressed in different units.

Transcript

00:01 Okay, so for this question, they want us to calculate how much energy is needed to raise the temperature of ethanol from 20 degrees celsius to 78 .29 degrees celsius and then evaporate the ethanol.

00:14 So we have one kilogram of ethanol.

00:17 They give us the specific heat to be 2 .44 joules per gram times kelvin and they give us the heat of vaporization to be 855 joules per gram.

00:27 So we need two equations solve this.

00:29 We need q is equal to m.

00:30 C delta t.

00:32 This is used for used to determine how much energy is needed to turn 20 degrees celsius to 78 .29 degrees celsius and q is equal to mhv.

00:47 This is needed to calculate how much energy is needed to evaporate the ethanol.

00:52 Right.

00:52 So we have the temperature in celsius so we need to convert that into kelvin.

00:59 Right.

00:59 So in order to convert that into kelvin.

01:00 Right.

01:00 So in order to convert celsius to kelvin, all we need to do is add 273 to whatever the celsius temperature is.

01:07 We get 293 kelvin.

01:09 Then we have 78 .2929 plus 273 and we get 3501 .29.

01:18 Now we have one kilogram of ethanol, but we see that in both of the sea and the heat of vaporization...

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