Calculate the amount of heat required to completely sublime 75.0 g of solid dry ice (CO 2 ) at its sublimation temperature. The heat of sublimation for carbon dioxide is 32.3 kJ/mol.

Hello. Everyone in this video, we're trying to calculate the amount of heat for the sublimation of 33.50 g of ammonia. So, we also have some given information. So the first thing that we're given is that the land heat of sublimation of ammonia is equal to this value right here. Another thing that's not told to us, but we can easily calculate is going to be the molar mass of ammonia. All right. And the molar mass of Ammonia is it is going to equal to 17.03 g Permal. So again, we have this piece of giving information and we found this on the side. All right. So to calculate for the amount of heat of sublimation, there's a formula. That formula is going to be Q equals M. L. So using this formula, my mass, that's going to be 33.5 grams. Then I'm going to go ahead and convert this grams to moles by using the molar mass which we have over here. So To cancel the g, I'll put 17.3 g on the bottom and on top. My numerator will be just be one more. Then what you can do next is canceling out the moles to get our killer jewels. We'll go ahead and use that given land heat of sublimation And to cancel out the most. We'll put one more on the dominator On top, we'll have 28 .97 Killer Jewels. As you can see here that the grams will cancel out moles will cancel out given us if you put everything here until the calculator. you got a Q value Of 56.99 killer jewels. And that's actually going to be our final answer, Which is the amount of heat for the sublimation of 33.5 programs of ammonia. Thank you all so much for watching.

Ch.12 - Liquids, Solids & Intermolecular Forces

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Tro 6th Edition

Ch.12 - Liquids, Solids & Intermolecular Forces

Problem 74

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Chapter 12, Problem 74

Calculate the amount of heat required to completely sublime 75.0 g of solid dry ice (CO₂) at its sublimation temperature. The heat of sublimation for carbon dioxide is 32.3 kJ/mol.

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Identify the given information: mass of dry ice (CO_2) is 75.0 g and the heat of sublimation is 32.3 kJ/mol.

Calculate the molar mass of CO_2. The molar mass of carbon (C) is approximately 12.01 g/mol and that of oxygen (O) is approximately 16.00 g/mol. Therefore, the molar mass of CO_2 is 12.01 + 2(16.00) g/mol.

Convert the mass of CO_2 from grams to moles using the formula: \( \text{moles of CO}_2 = \frac{\text{mass of CO}_2}{\text{molar mass of CO}_2} \).

Use the heat of sublimation to calculate the total heat required. Multiply the moles of CO_2 by the heat of sublimation: \( \text{heat required} = \text{moles of CO}_2 \times 32.3 \text{ kJ/mol} \).

The result from the previous step gives the total amount of heat required to completely sublime the given mass of dry ice.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Sublimation

Sublimation is the phase transition in which a substance changes directly from a solid to a gas without passing through the liquid phase. In the case of dry ice (solid CO2), it sublimates at temperatures below -78.5°C. Understanding sublimation is crucial for calculating the heat required for this process, as it involves energy changes associated with breaking intermolecular forces.

Heat of Sublimation

The heat of sublimation is the amount of energy required to convert one mole of a solid directly into a gas at a constant temperature and pressure. For carbon dioxide, this value is 32.3 kJ/mol, indicating the energy needed to overcome the forces holding the solid together. This concept is essential for calculating the total heat needed for the sublimation of a given mass of dry ice.

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). For carbon dioxide (CO2), the molar mass is approximately 44.01 g/mol. Knowing the molar mass is vital for converting the mass of dry ice (75.0 g) into moles, which allows for the application of the heat of sublimation in the heat calculation.