Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 12: Problem 76

Freeze-dried coffee is prepared by freezing a sample of brewed coffee and then removing the ice component by vacuum-pumping the sample. Describe the phase changes taking place during these processes.

Short Answer

Expert verified
The process of freeze-drying involves two phase transitions. Initially, the liquid coffee freezes into solid ice. Then, vacuum pumping causes the ice to undergo sublimation, directly transitioning from solid to gas, leaving the coffee behind in a solid, dried state.

Step by step solution

01

Identify Initial State

Initially, the coffee is in a liquid state. This is the initial state before any phase changes occur.
02

Freezing the Coffee

When the coffee is frozen, it undergoes a phase transition from liquid to solid. This is known as freezing. The water in the coffee forms solid ice crystals.
03

Removing Ice by Vacuum Pumping

The process of vacuum-pumping to remove the ice brings about a process called sublimation. In sublimation, substances transition directly from a solid state to a gas state, bypassing the liquid state. Here, the solid ice turns directly into water vapor.
04

Final State

After the ice has been sublimated, the coffee is left behind in a dried state. Thus, from the initial liquid state, the coffee undergoes phase transitions to finally reach a solid dried state.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Explain in terms of intermolecular forces why (a) \(\mathrm{NH}_{3}\) has a higher boiling point than \(\mathrm{CH}_{4}\) and \((\mathrm{b}) \mathrm{KCl}\) has a higher melting point than \(\mathrm{I}_{2}\).

Crystalline silicon has a cubic structure. The unit cell edge length is \(543 \mathrm{pm}\). The density of the solid is \(2.33 \mathrm{~g} / \mathrm{cm}^{3}\). Calculate the number of \(\mathrm{Si}\) atoms in one unit cell.

The molar heats of fusion and sublimation of molecular iodine are \(15.27 \mathrm{~kJ} / \mathrm{mol}\) and \(62.30 \mathrm{~kJ} / \mathrm{mol}\), respectively. Estimate the molar heat of vaporization of liquid iodine.

Vapor pressure measurements at several different temperatures are shown here for mercury. Determine graphically the molar heat of vaporization for mercury. \(\begin{array}{cccccc}t\left({ }^{\circ} \mathrm{C}\right) & 200 & 250 & 300 & 320 & 340 \\ P(\mathrm{mmHg}) & 17.3 & 74.4 & 246.8 & 376.3 & 557.9\end{array}\)

A solid is hard, brittle, and electrically nonconducting. Its melt (the liquid form of the substance) and an aqueous solution containing the substance do conduct electricity. Classify the solid.
See all solutions

Recommended explanations on Chemistry Textbooks

Inorganic Chemistry

Read Explanation

Chemistry Branches

Read Explanation

Chemical Reactions

Read Explanation

The Earths Atmosphere

Read Explanation

Physical Chemistry

Read Explanation

Making Measurements

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free