The Physics Classroom » Physics Interactives » Chemistry » Ammonia Factory » Teacher Notes

Teacher Notes

Notes:

The Ammonia Factory Interactive is an adjustable-size file that displays nicely on smart phones, on tablets such as the iPad, on Chromebooks, and on laptops and desktops. The size of the Interactive can be scaled to fit the device that it is displayed on. The compatibility with smart phones, iPads, other tablets, and Chromebooks make it a perfect tool for use in a 1:1 classroom.

 

Teaching Ideas and Suggestions:

This Interactive was designed with the Next Generation Science Standards in mind. It provides a student an interactive experience in engineering design. Students play the role of chemical engineer as they conduct a pilot study of a production line at an ammonia factory. The goal of the simulation is to determine how to adjust variables in order to optimize ammonia production. Students can adjust the following variables:
  • Reactor Temperature (0°C to 1500 °C)
  • Reactor Pressure (1 atm to 1500 atm)
  • Nitrogen Flow Rate (0 L/min to 200 L/min, at STP conditions)
  • Hydrogen Flow Rate (0 L/min to 200 L/min, at STP conditions)
Once variables have been modified, the simulation can be run with such values for a day and the NH3 production rate and profits are reported along with the percent yield and some other output variables. Students have 180 days (i.e., 180 trials) to determine the conditions that result in the greatest ammonia yield and company profits. According to the storyline, they must file a report of their findings to the Board of Directors after completion of the study.

Results for all 180 trials are collected and displayed on the screen. A tap on the Clipboard will slide in a table of accumulated data. The last 10 trials are displayed. Arrows below the table allow a student to navigate to previous trials. The column headings of the table are interactive. A tap on a column heading will slide in a field with an explanation of that quantity and a few brief sentences hinting at how to improve the outcome.

The percent yield of ammonia is an important output variable in this study. Students will need to find what set of parameters optimize the percent yield. As is the case in the real work of ammonia production, the percent yield is impacted by equilibrium principles, kinetics, stoichiometry, and thermodynamic stability. While low temperatures favor ammonia production from an equilibrium viewpoint, higher temperatures increase reaction rates and increase the rate of ammonia production. Similarly, while higher temperatures may increase reaction rates, they also increase decomposition rates of the product. Finally, stoichiometry will need to be used to determine the proper reactant ratio of hydrogen and nitrogen.

On start-up, a cost of the raw materials (hydrogen and nitrogen) and a sale price of ammonia are selected at random from a collection of 10 possible values. As such, two side-by-side students cannot assume the same results from their studies. A two-character price index code is reported to the student on start-up. They are encouraged to write it down. If they shut down the browser or exit the page, a new price index would be randomly issued to the student on their next visit. But by using the original two-character code, they can receive the same market prices that were used during their first visit. If a student shuts down the browser, saved data will be lost. We encourage periodic screenshots of the data tables (every 10 trials) or old-fashioned data collection. 

 

Student Activity Sheet

This Interactive is accompanied by a Student Activity Sheet. The activity provides guidance and structure to students in order to conduct the study described in the above paragraphs. Teachers are permitted to print and distribute the activity sheet to their classes. View Student Activity Sheet.

We have completed an interactive Science Reasoning Center accompaniment to this activity that provides a follow-up and is aligned quite closely with Next Generation Science Standards. The activity can be found here: Ammonia Factory Science Reasoning Center activity.


 

Next Generation Science Standards

When designing this simulation, we were targeting some of the following Next Generation Science Standards and performance expectations:
  • Performance Expectation; Chemical Reactions, HS-PS1.5: Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.
  • Performance Expectation; Chemical Reactions, HS-PS1.6: Refine the design of a chemical system by specifying a change in conditions that would produce increased amounts of products at equilibrium.
  • Performance Expectation; Engineering Design, HS-ETS1-3: Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including cost, safety, reliability, and aesthetics as well as possible social, cultural, and environmental impacts.
  • Performance Expectation; Engineering Design, HS-ETS1-4: Use a computer simulation to model the impact of proposed solutions to a complex real-world problem with numerous criteria and constraints on interactions within and between systems relevant to the problem.
  • Science and Engineering Practices;Asking Questions and Defining Problems: Define a design problem that involves the development of a process or system with interacting components and criteria and constraints that may include social, technical and/or environmental considerations.
  • Science and Engineering Practices; Developing and Using Models: Develop a complex model that allows for manipulation and testing of a proposed process or system.
  • Science and Engineering Practices; Developing and Using Models: Develop and/or use a model (including mathematical and computational) to generate data to support explanations, predict phenomena, analyze systems, and/or solve problems.
  • Science and Engineering Practices; Planning and Carrying Out Investigations: Manipulate variables and collect data about a complex model of a proposed process or system to identify failure points or improve performance relative to criteria for success or other variables.
  • Science and Engineering Practices; Analyzing and Interpretting Data: Analyze data to identify design features or characteristics of the components of a proposed process or system to optimize it relative to criteria for success.
  • Science and Engineering Practices; Constructing Explanations and Designing Solutions: Evaluate a solution to a complex real world problem, based on scientific knowledge, student-generated sources of evidence, prioritized criteria, and tradeoff considerations.
  • Science and Engineering Practices; Obtaining, Evaluating, and Communicating Information: Communicate scientific and/or technical information or ideas (e.g. about phenomena and/or the process of development and the design and performance of a proposed process or system) in multiple formats (including orally, graphically, textually, and mathematically).
  • Cross-cutting Concepts; Patterns: Patterns of performance of designed systems can be analyzed and interpreted to reengineer and improve the system.
  • Cross-cutting Concepts; Cause and Effect: Systems can be designed to cause a desired effect.
  • Cross-cutting Concepts; Systems and System Models: Models can be used to predict the behavior of a system, but these predictions have limited precision and reliability due to the assumptions and approximations inherent in models.
  • Cross-cutting Concepts; Structure and Function: Investigating or designing new systems or structures requires a detailed examination of the properties of different materials, the structures of different components, and connections of components to reveal its function and/or solve a problem.
  • Cross-cutting Concepts; Stability and Change: Much of science deals with constructing explanations of how things change and how they remain stable.
  • Disciplinary Core Idea; Chemical Reactions, PS1.B: In many situations, a dynamic and condition-dependent balance between a reaction and the reverse reaction determines the numbers of all types of molecules present.
  • Disciplinary Core Idea; ETS1.B: Developing Possible Solutions: When evaluating solutions, it is important to take into account a range of constraints, including cost, safety, reliability, and aesthetics, and to consider social, cultural, and environmental impacts.