Calculate the heat change at 100^∘ C for each of the following and indicate whether heat was abs

step 1 Problem 46, we're still on calculating heat change. Okay, so we have condensation and vaporizati

Calculate the heat change at 100^∘ C for each of the...

Calculate the heat change at $100^{\circ} \mathrm{C}$ for each of the following and indicate whether heat was absorbed or released: a. calories to condense $10.0 \mathrm{g}$ of steam b. joules to condense $7.60 \mathrm{g}$ of steam c. kilocalories to vaporize 44 g of water d. kilojoules to vaporize $5.00 \mathrm{kg}$ of water

Calculate the heat change at $100^{\circ} \mathrm{C}$ for each of the following and indicate whether heat was absorbed or released:
a. calories to condense $10.0 \mathrm{g}$ of steam
b. joules to condense $7.60 \mathrm{g}$ of steam
c. kilocalories to vaporize 44 g of water
d. kilojoules to vaporize $5.00 \mathrm{kg}$ of water

Key Concepts

Energy and Unit Conversion

Energy calculations in phase change processes often require conversion between different units such as calories, joules, kilocalories, and kilojoules. Accurate unit conversion is crucial for ensuring consistency and correctness in thermodynamic calculations. This concept involves understanding conversion factors and applying them correctly to obtain the desired energy unit.

Enthalpy of Vaporization/Condensation

The enthalpy of vaporization is the heat required to vaporize a unit mass of a liquid at its boiling point, while the enthalpy of condensation is the heat released when the vapor condenses into a liquid. Although these values are equal in magnitude, the sign is opposite: vaporization is endothermic (absorbing heat) and condensation is exothermic (releasing heat). These concepts are fundamental in calculating the energy changes during phase transitions.

Latent Heat

Latent heat is the amount of energy released or absorbed by a substance during a phase change at a constant temperature and pressure. It is specific to the substance and the particular phase transition (e.g., vaporization or condensation) and is typically expressed per unit mass. During a phase change, all added or removed energy is used in overcoming intermolecular forces rather than changing the temperature of the substance.

Phase Change (Vaporization and Condensation)

Phase changes involve the transformation of a substance from one state of matter to another, such as from liquid to gas (vaporization) or from gas to liquid (condensation). The processes require or release energy in the form of latent heat. In vaporization, energy is absorbed to convert liquid to vapor, while in condensation, energy is released when vapor turns into liquid.

Transcript

00:01 Problem 46, we're still on calculating heat change.

00:04 Okay, so we have condensation and vaporization.

00:08 And for that reason, what i have here are the values for heat of vaporization of water.

00:14 Okay.

00:16 So, let's start with identifying whether we are absorbing or releasing heat.

00:21 Parts a and b is condensation.

00:24 Okay, so we're turning gas to liquid.

00:27 Okay, so when you're turning gas to liquid, that means you are taking out heat from gas.

00:35 Okay, so if you're taking out heat, that means that steam is releasing it.

00:43 And on the other hand, if you're vaporizing, you're turning liquid to gas, that means you're putting in heat to water.

00:50 So that means that water is absorbing it.

00:56 So moving on to our calculations, starting with part a.

01:00 So i'll just put it right over here.

01:05 Part a i got 10 .0 kilograms of water or steam actually and first i need to convert this to grams okay since our values here use the unit grams so 1 ,000 grams is equal to 1 kilogram okay and next we are multiplying that by 540 calories per because part a is asking for the unit calories.

01:40 So i'm using 540 calories per gram.

01:47 So the units would cancel, kilogram and kilogram and grams and grams.

01:54 Okay, all that's left here is our calculator...

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