The Liquid Nitrogen Cloud

Liquid Nitrogen Cloud

One of my favorite experiments to conduct is the liquid nitrogen cloud. As long as you can get some liquid nitrogen, it is incredibly easy to carry out. All you have to do is pour some hot water into liquid nitrogen and a massive cloud results. Check it out (also, be sure to check out the video posted further below):

 

 

What a fantastic experiment! It’s hard to imagine that such absolutely remarkable results originate from an experiment that is so easy to set up and carry out. I’ve wondered for some time how the cloud forms in this experiment. I’ve seen claims that the cloud forms as hot water vaporizes the liquid nitrogen upon contact, and the resulting cold, rising nitrogen vapor cools atmospheric water vapor, condensing it into a cloud.1 I’m not convinced of this explanation for two reasons. First, you will note that the cloud formed is massive and thick. It seems to me that there isn’t enough atmospheric water vapor in the immediate vicinity of the rising, cold nitrogen gas to produce a cloud of this size. Also, this experiment is reminiscent of the dry ice cloud, in which a cloud forms when dry ice is placed in water. During the dry ice experiment, it is easy to show that the cloud forms not from atmospheric water vapor, but rather from the water into which the dry ice is placed.2,3 I decided to run some experiments to see if the water in the liquid nitrogen cloud originated from the water poured onto the nitrogen rather than atmospheric water vapor. I ran various trials of pouring water into liquid nitrogen – and also liquid nitrogen into water – and observed the results. The results of my explorations led to a working hypothesis that the cloud originates at the interface between liquid nitrogen, hot water, and expanding nitrogen gas (Figure 1). In this scenario, the contact of the two liquids causes rapid vaporization of nitrogen, resulting in large pockets of expanding nitrogen gas that rises and pushes through the liquid water (Figure 1, middle). Some of this liquid water evaporates into these expanding plumes of cold nitrogen gas (Figure 1, right, blue arrows), and then rapidly condenses into large pockets containing condensed water vapor – a cloud (Figure 1, right, red equations).

 

Figure 1: Diagram summarizing the hypothesis for the formation of the cloud during the liquid nitrogen experiment.

 

The image in Figure 1 is overly schematic; the explosive nature of this process certainly pulverizes the liquid water into innumerable liquid droplets. The basic idea, however, is that all surfaces of contact between liquid water and cold gaseous nitrogen results in tiny droplets of condensed water vapor. To summarize in equations:

H2O (l, in bulk water and pulverized droplets) à H2O (g, in pockets of cool gaseous nitrogen)

H2(g, in pockets of cool gaseous nitrogen) à H2O (l, droplets, in cool gaseous nitrogen)

You can see the results of my experiments in the video below, and judge for yourself what you think of my working hypothesis.

 

 

If you have comments or criticisms about how I think the liquid nitrogen cloud forms, I’d love to hear from you – especially if you have suggestions for possible experiments to improve my understanding of what is happening in this fascinating experiment.

References:

1. See for example, (Accessed July, 2019).

2. (Accessed July, 2019).

3. Kuntzleman, Thomas S., Ford, Nathan, No, Jin-Hwan, Ott, Mark E., J. Chem. Ed.201592

Collection: 

Safety

General Safety

For Laboratory Work: Please refer to the ACS .  

For Demonstrations: Please refer to the ACS Division of Chemical Education .

Other Safety resources

: Recognize hazards; Assess the risks of hazards; Minimize the risks of hazards; Prepare for emergencies

 

Safety: Video Demonstration

Demonstration videos presented here are not meant as tools to teach chemical demonstration techniques. They are meant as a tool for classroom use. The demonstrations may present safety hazards or show phenomena that are difficult for an entire class to observe in a live demonstration.

Those performing the demonstrations shown in this video have been trained and adhere to best safety practices.

Anyone thinking about performing a chemistry demonstration should first read and then adhere to the  These guidelines are also available at ChemEd X.

NGSS

Asking questions and defining problems in grades 9–12 builds from grades K–8 experiences and progresses to formulating, refining, and evaluating empirically testable questions and design problems using models and simulations.

Summary:

Asking questions and defining problems in grades 9–12 builds from grades K–8 experiences and progresses to formulating, refining, and evaluating empirically testable questions and design problems using models and simulations.

questions that challenge the premise(s) of an argument, the interpretation of a data set, or the suitability of a design.

Assessment Boundary:
Clarification:

Scientific questions arise in a variety of ways. They can be driven by curiosity about the world (e.g., Why is the sky blue?). They can be inspired by a model’s or theory’s predictions or by attempts to extend or refine a model or theory (e.g., How does the particle model of matter explain the incompressibility of liquids?). Or they can result from the need to provide better solutions to a problem. For example, the question of why it is impossible to siphon water above a height of 32 feet led Evangelista Torricelli (17th-century inventor of the barometer) to his discoveries about the atmosphere and the identification of a vacuum.

Questions are also important in engineering. Engineers must be able to ask probing questions in order to define an engineering problem. For example, they may ask: What is the need or desire that underlies the problem? What are the criteria (specifications) for a successful solution? What are the constraints? Other questions arise when generating possible solutions: Will this solution meet the design criteria? Can two or more ideas be combined to produce a better solution?

Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories.

Summary:

Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories. Construct and revise an explanation based on valid and reliable evidence obtained from a variety of sources (including students’ own investigations, models, theories, simulations, peer review) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.

Assessment Boundary:
Clarification:

Modeling in 9–12 builds on K–8 and progresses to using, synthesizing, and developing models to predict and show relationships among variables between systems and their components in the natural and designed worlds.

Summary:

Modeling in 9–12 builds on K–8 and progresses to using, synthesizing, and developing models to predict and show relationships among variables between systems and their components in the natural and designed worlds. Use a model to predict the relationships between systems or between components of a system.

Assessment Boundary:
Clarification:

Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories.

Summary:

Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories. Construct and revise an explanation based on valid and reliable evidence obtained from a variety of sources (including students’ own investigations, models, theories, simulations, peer review) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.

Assessment Boundary:
Clarification:

Engaging in argument from evidence in 9–12 builds on K–8 experiences and progresses to using appropriate and sufficient evidence and scientific reasoning to defend and critique claims and explanations about natural and designed worlds. Arguments may also come from current scientific or historical episodes in science.

Summary:

Engaging in argument from evidence in 9–12 builds on K–8 experiences and progresses to using appropriate and sufficient evidence and scientific reasoning to defend and critique claims and explanations about natural and designed worlds. Arguments may also come from current scientific or historical episodes in science.
Evaluate the claims, evidence, and reasoning behind currently accepted explanations or solutions to determine the merits of arguments.

Assessment Boundary:
Clarification:

Planning and carrying out investigations in 9-12 builds on K-8 experiences and progresses to include investigations that provide evidence for and test conceptual, mathematical, physical, and empirical models.

Summary:

Planning and carrying out investigations in 9-12 builds on K-8 experiences and progresses to include investigations that provide evidence for and test conceptual, mathematical, physical, and empirical models. Plan and conduct an investigation individually and collaboratively to produce data to serve as the basis for evidence, and in the design: decide on types, how much, and accuracy of data needed to produce reliable measurements and consider limitations on the precision of the data (e.g., number of trials, cost, risk, time), and refine the design accordingly.

Assessment Boundary:
Clarification:

Students who demonstrate understanding can plan and conduct an investigation of the properties of water and its effects on Earth materials and surface processes.

More information about all DCI for HS-ESS2 can be found and further resources at.

Summary:

Students who demonstrate understanding can plan and conduct an investigation of the properties of water and its effects on Earth materials and surface processes.

Assessment Boundary:
Clarification:

Emphasis is on mechanical and chemical investigations with water and a variety of solid materials to provide the evidence for connections between the hydrologic cycle and system interactions commonly known as the rock cycle. Examples of mechanical investigations include stream transportation and deposition using a stream table, erosion using variations in soil moisture content, or frost wedging by the expansion of water as it freezes. Examples of chemical investigations include chemical weathering and recrystallization (by testing the solubility of different materials) or melt generation (by examining how water lowers the melting temperature of most solids).