Question

Which of these processes are nonspontaneous? Are the nonspontaneous processes impossible? a. a bike going up a hill b. a meteor falling to Earth c. obtaining hydrogen gas from liquid water d. a ball rolling down a hill

Short answer

The nonspontaneous processes are a bike going up a hill and obtaining hydrogen gas from liquid water. These processes are not impossible; they just require continuous external input of energy.

Step-by-step solution

Understanding Spontaneous Processes

A spontaneous process is one that occurs without any continuous external influence. To determine if a process is spontaneous or nonspontaneous, one should consider whether the process can progress on its own once it has been initiated.

Analyzing the Bike Going Up a Hill

A bike going up a hill would require continuous input of energy, typically from a cyclist pedalling. Without this input, the process would not occur on its own. Therefore, the process is nonspontaneous.

Evaluating the Meteor Falling to Earth

A meteor falling to Earth is an example of a spontaneous process. Once the meteor enters the Earth's atmosphere, gravity will cause it to continue falling without the need for any additional energy input.

Considering Obtaining Hydrogen Gas from Liquid Water

Obtaining hydrogen gas from liquid water through electrolysis requires a continuous supply of electrical energy to split water into hydrogen and oxygen. This process does not occur on its own without input of energy, making it nonspontaneous.

Assessing a Ball Rolling Down a Hill

A ball rolling down a hill is considered a spontaneous process as it will continue rolling down without the need for continuous external energy, due to the gravitational pull.

Understanding the Difference Between Nonspontaneous and Impossible

Nonspontaneous processes are not necessarily impossible; they simply require continuous external input of energy to occur. A bike going uphill and obtaining hydrogen from water are nonspontaneous, but not impossible as they can occur with the necessary energy input.

Key concepts

Spontaneous Processes

In thermodynamics, a spontaneous process is one that occurs naturally without the need for an ongoing energy input. For example, when you see a ball rolling downhill, it's displaying a spontaneous movement—it rolls without needing anything else to keep it going. Once started, it capitalizes on the gravitational pull to continue its journey downward.

This concept is pivotal in understanding why certain events happen around us without us having to do anything. For instance, ice melting on a warm day is a spontaneous process; the ambient temperature is all that's needed to drive the change from solid to liquid.

Thermodynamics

Thermodynamics is the study of heat, energy, and work, and how they interact. It's a branch of physics that plays a vital role in our understanding of spontaneous processes and nonspontaneous ones. The Laws of Thermodynamics lay the foundational principles that govern all energetic exchanges and transformations.

One aspect of thermodynamics is the concept of entropy, a measure of disorder or randomness. Spontaneous processes often lead to an increase in entropy, signifying a transition toward greater disorder or the spreading out of energy.

Energy Input

For certain processes to take place, an energy input is necessary. In thermodynamics, this energy can be of any form—electrical, chemical, mechanical, or thermal. Nonspontaneous processes, like pedaling a bike uphill, don't just happen on their own—they require a continuous supply of energy to progress.

When we provide energy to such systems, we're effectively pushing them to do something that wouldn't occur naturally. It's this input that can turn the nonspontaneous into reality. Though nonspontaneous, these processes are not impossible; they simply need a boost from an external energy source.

Electrolysis

Electrolysis is a classic example of a nonspontaneous chemical process, wherein electrical energy is used to provoke a chemical change. This technique is employed to separate the elements in a compound—a well-known application being the extraction of hydrogen and oxygen from water.

During electrolysis, an electric current is passed through the water, causing it to split into its constituent gases. Unlike a ball rolling down a hill, which happens on its own, electrolysis needs a constant supply of energy to maintain the reaction. Despite being nonspontaneous, with the right setup and energy source, electrolysis efficiently carries out its intended task.