What is entropy in chemistry series#

Good to know: spontaneous ≠ instantaneous! Even if a change is spontaneous, this doesn’t necessarily mean that it happens quickly.

Equal volumes of olive oil and vinegar dissolve together to make a salad dressing.

The smell of perfume spray spreads throughout a room.

Water in a glass on your desk decomposes to hydrogen and oxygen.

Water evaporates when it is spilled on a hot surface.

Ice melts when dropped in a cup of warm water.

Which of the following processes are spontaneous? Being able to predict what processes will be spontaneous is how we apply the second law. For example, you can drop a ball from above your head and it falls to the floor (spontaneous) but you need to provide energy to the ball to place it over your head again. What is a Spontaneous Change?Ī spontaneous change is any change that happens freely in time. In this activity we will use careful observations of the process of dissolving salts in water to more deeply understand the second law. It grew in the nineteenth century out of observations made about big things like steam engines, and today it is often used to illuminate the conceptual, chemical world of tiny things like atoms, ions, and molecules. The second law of thermodynamics may be expressed in many ways, and it has been used by chemists to understand everything from the work of a steam engine to the direction of time.

The underlined words have a very particular meaning that we need to know before we can understand the second law. For example, one way that chemists state the second law of thermodynamics is that in any spontaneous change, the entropy of the universe increases. The entire architecture of thermodynamics is built on carefully defined terms, many of which have an everyday meaning that is not exactly what chemists mean when they use the term. Thermodynamics is a way of describing energy transformations when a system changes from one state to another. This investigation could be incorporated into a unit on chemical changes or thermodynamics. What does spontaneous mean? What kinds of processes in your experience happen spontaneously? Are there any differences between them? Incorporating into the Curriculum This lab is designed for students to work together, discussing and answering the questions posed while proceeding through the step-by-step treatment of the second law. One class period, approximately 45–50 minutes.

3 150-mL beakers, stirring rod Optional Materials for the Post-Lab Demo.

10 g ammonium chloride or ammonium nitrate.

Dispose of solutions according to local regulations.

Vapor may cause weakness, fatigue, nausea, and headache. In the event of contact, wash affected areas with water.

Calcium chloride can be an irritant to body tissues.

May emit toxic vapors of NOx and NH 3 when heated to decomposition.

Ammonium nitrate is a strong oxidizer.

Ammonium chloride can be an irritant to body tissues.Be sure you and the students wear properly fitting goggles.Given prior knowledge of the thermodynamic terms entropy, enthalpy, and spontaneous processes, students will gain a deeper understanding of how ΔG = ΔH sys – T ΔS sys expresses the second law of thermodynamics by exploring energy transfer between system and surroundings as salts dissolve.

What is entropy in chemistry series#

In this investigation, students will explore basic thermodynamic concepts, including spontaneity, entropy, and enthalpy through a series of guided questions and procedures.