Various items (hot dogs, bananas, flowers, racquetballs, plastic cups) show properties akin to glass when chilled in liquid nitrogen.1-4 Objects such as racquetballs and plastics behave in this manner because they are made of polymers, and polymers can become cooled below what is known as the glass transition temperature (Tg) for the polymer.3-4 Above Tg plastics are elastic, near Tg plastics lose their elasticity, and below Tg plastics become brittle (Video 1).
Video 1: SCRUB DADDY vs. LIQUID NITROGEN, Tommy Technetium YouTube Channel, October 2022.
Did you know that some metals behave in a similar fashion? Many metals display what is known as a ductile to brittle transition temperature (DBT).5-9 When a metal is hammered above its DBT, the metal absorbs the energy from the impact, which causes the metal to be deformed. Thus, a metal above its DBT can be formed into a wire or sheet. That is, the metal is ductile and malleable. On the other hand, a metal below its DBT does not absorb energy from an impact when struck. Instead, it behaves like glass (Video 2).
Video 2: Pennies vs. Liquid Nitrogen, Tommy Technetium YouTube Channel, January 2023.
Interestingly, metals with atoms that arrange in a body centered cubic arrangement display a DBT, while metals arranging in face centered cubic or hexagonal close packed arrangements do not.6,7 Furthermore, the presence of dopants or impurities in a metal can drastically change its DBT.6-9 For example, measurements have demonstrated that higher amounts of manganese and sulfur were present in the steel used to construct the Titanic (Video 3).8,9 The presence of these elements in the steel lowered its DBT, contributing to the damage done to the Titanic on impact with the iceberg.8,9 Similar analyses of the metal used to construct the Liberty Ships has demonstrated a similar effect.6,7
Video 3: Chemistry and the Sinking of the Titanic, Tommy Technetium YouTube Channel, December 2022.
References:
- Kenneth H. Lothrop, Demonstrations in cryogenics, Journal of Chemical Education, 1978, 55, 8, 531-532.
- Lee Marek, Be Cool to Your School, Flinn Scientific.
- Thomas S. Kuntzleman, David Sellers, Rachel Hoffmeyer, "Having a Ball with Chemistry": More things to try, Journal of Chemical Education, 2008, 85, 11, 1478-1480.
- Dean Campbell,Polypropylene and the Cold Snap, ChemEd X, Feb 2021 (accessed 1/2/23)
- Rahul Wadher BEng, AMIMechE AIMMM, What is the Ductile-Brittle Transition Temperature?, ASAMS, May 2021 (accessed 1/2/23)
- Challenges 2016, 7, 20; doi:10.3390/challe7020020
- Jeremy Jordan, Ductile to brittle transitions in materials, Nov 2016 (accessed 1/2/23)
- John J. Gilman, In Defense of the Metallic Bond, Journal of Chemical Education, 1999, 76, 10, 1330-1331 (Titanic ductile brittle)
- Katherine Felkins, H. P. Leigh Jr., A. Jankovic, The royal mail ship Titanic: Did a metallurgical failure cause a night to remember? Journal of Metals, 1998, 50, 1, 12-18.
Preview image: Titanic Sinking, engraving by Willy Stöwer. https://en.wikipedia.org/wiki/
Safety
Safety: Video Demonstration
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 ACS Safety Guidelines for Chemical Demonstrations (2016) These guidelines are also available at ChemEd X.
General Safety
General Safety
For Laboratory Work: Please refer to the ACS Guidelines for Chemical Laboratory Safety in Secondary Schools (2016).
For Demonstrations: Please refer to the ACS Division of Chemical Education Safety Guidelines for Chemical Demonstrations.
Other Safety resources
RAMP: Recognize hazards; Assess the risks of hazards; Minimize the risks of hazards; Prepare for emergencies
NGSS
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.
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.
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.
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.
Matter and its Interactions help students formulate an answer to the question, “How can one explain the structure, properties, and interactions of matter?” The PS1 Disciplinary Core Idea from the NRC Framework is broken down into three subideas: the structure and properties of matter, chemical reactions, and nuclear processes. Students are expected to develop understanding of the substructure of atoms and to provide more mechanistic explanations of the properties of substances. Chemical reactions, including rates of reactions and energy changes, can be understood by students at this level in terms of the collisions of molecules and the rearrangements of atoms. Students are able to use the periodic table as a tool to explain and predict the properties of elements. Using this expanded knowledge of chemical reactions, students are able to explain important biological and geophysical phenomena. Phenomena involving nuclei are also important to understand, as they explain the formation and abundance of the elements, radioactivity, the release of energy from the sun and other stars, and the generation of nuclear power. Students are also able to apply an understanding of the process of optimization in engineering design to chemical reaction systems. The crosscutting concepts of patterns, energy and matter, and stability and change are called out as organizing concepts for these disciplinary core ideas. In the PS1 performance expectations, students are expected to demonstrate proficiency in developing and using models, planning and conducting investigations, using mathematical thinking, and constructing explanations and designing solutions; and to use these practices to demonstrate understanding of the core ideas.
*More information about this category of NGSS can be found at https://www.nextgenscience.org/dci-arrangement/hs-ps1-matter-and-its-interactions.
"Matter and its Interactions help students formulate an answer to the question, “How can one explain the structure, properties, and interactions of matter?” The PS1 Disciplinary Core Idea from the NRC Framework is broken down into three subideas: the structure and properties of matter, chemical reactions, and nuclear processes. Students are expected to develop understanding of the substructure of atoms and to provide more mechanistic explanations of the properties of substances. Chemical reactions, including rates of reactions and energy changes, can be understood by students at this level in terms of the collisions of molecules and the rearrangements of atoms. Students are able to use the periodic table as a tool to explain and predict the properties of elements. Using this expanded knowledge of chemical reactions, students are able to explain important biological and geophysical phenomena. Phenomena involving nuclei are also important to understand, as they explain the formation and abundance of the elements, radioactivity, the release of energy from the sun and other stars, and the generation of nuclear power. Students are also able to apply an understanding of the process of optimization in engineering design to chemical reaction systems. The crosscutting concepts of patterns, energy and matter, and stability and change are called out as organizing concepts for these disciplinary core ideas. In the PS1 performance expectations, students are expected to demonstrate proficiency in developing and using models, planning and conducting investigations, using mathematical thinking, and constructing explanations and designing solutions; and to use these practices to demonstrate understanding of the core ideas."
Students who demonstrate understanding can apply scientific and engineering ideas to design, evaluate, and refine a device that minimizes the force on a macroscopic object during a collision.
*More information about all DCI for HS-PS2 can be found at https://www.nextgenscience.org/dci-arrangement/hs-ps2-motion-and-stability-forces-and-interactions.
Students who demonstrate understanding can apply scientific and engineering ideas to design, evaluate, and refine a device that minimizes the force on a macroscopic object during a collision.
Assessment is limited to qualitative evaluations and/or algebraic manipulations.
Examples of evaluation and refinement could include determining the success of the device at protecting an object from damage and modifying the design to improve it. Examples of a device could include a football helmet or a parachute.
At the high school level students are expected to engage with major global issues at the interface of science, technology, society and the environment, and to bring to bear the kinds of analytical and strategic thinking that prior training and increased maturity make possible. As in prior levels, these capabilities can be thought of in three stages—defining the problem, developing possible solutions, and improving designs.
Defining the problem at the high school level requires both qualitative and quantitative analysis. For example, the need to provide food and fresh water for future generations comes into sharp focus when considering the speed at which world population is growing, and conditions in countries that have experienced famine. While high school students are not expected to solve these challenges, they are expected to begin thinking about them as problems that can be addressed, at least in part, through engineering.
Developing possible solutions for major global problems begins by breaking them down into smaller problems that can be tackled with engineering methods. To evaluate potential solutions students are expected to not only consider a wide range of criteria, but to also recognize that criteria need to be prioritized. For example, public safety or environmental protection may be more important than cost or even functionality. Decisions on priorities can then guide tradeoff choices.
Improving designs at the high school level may involve sophisticated methods, such as using computer simulations to model proposed solutions. Students are expected to use such methods to take into account a range of criteria and constraints, to try and anticipate possible societal and environmental impacts, and to test the validity of their simulations by comparison to the real world.
Connections with other science disciplines help high school students develop these capabilities in various contexts. For example, in the life sciences students are expected to design, evaluate, and refine a solution for reducing human impact on the environment (HS-LS2-7) and to create or revise a simulation to test solutions for mitigating adverse impacts of human activity on biodiversity (HS-LS4-6). In the physical sciences students solve problems by applying their engineering capabilities along with their knowledge of conditions for chemical reactions (HS-PS1-6), forces during collisions (HS-PS2-3), and conversion of energy from one form to another (HS-PS3-3). In the Earth and space sciences students apply their engineering capabilities to reduce human impacts on Earth systems, and improve social and environmental cost-benefit ratios (HS-ESS3-2, HS-ESS3- 4).
By the end of 12th grade students are expected to achieve all four HS-ETS1 performance expectations (HS-ETS1-1, HS-ETS1-2, HS-ETS1-3, and HS-ETS1-4) related to a single problem in order to understand the interrelated processes of engineering design. These include analyzing major global challenges, quantifying criteria and constraints for solutions; breaking down a complex problem into smaller, more manageable problems, evaluating alternative solutions based on prioritized criteria and trade-offs, and using a computer simulation to model the impact of proposed solutions. While the performance expectations shown in High School Engineering Design couple particular practices with specific disciplinary core ideas, instructional decisions should include use of many practices that lead to the performance expectations.
At the high school level students are expected to engage with major global issues at the interface of science, technology, society and the environment, and to bring to bear the kinds of analytical and strategic thinking that prior training and increased maturity make possible. As in prior levels, these capabilities can be thought of in three stages—defining the problem, developing possible solutions, and improving designs.
By the end of 12th grade students are expected to achieve all four HS-ETS1 performance expectations (HS-ETS1-1, HS-ETS1-2, HS-ETS1-3, and HS-ETS1-4) related to a single problem in order to understand the interrelated processes of engineering design. These include analyzing major global challenges, quantifying criteria and constraints for solutions; breaking down a complex problem into smaller, more manageable problems, evaluating alternative solutions based on prioritized criteria and trade-offs, and using a computer simulation to model the impact of proposed solutions. While the performance expectations shown in High School Engineering Design couple particular practices with specific disciplinary core ideas, instructional decisions should include use of many practices that lead to the performance expectations.
Defining the problem at the high school level requires both qualitative and quantitative analysis. For example, the need to provide food and fresh water for future generations comes into sharp focus when considering the speed at which world population is growing, and conditions in countries that have experienced famine. While high school students are not expected to solve these challenges, they are expected to begin thinking about them as problems that can be addressed, at least in part, through engineering.
Developing possible solutions for major global problems begins by breaking them down into smaller problems that can be tackled with engineering methods. To evaluate potential solutions students are expected to not only consider a wide range of criteria, but to also recognize that criteria need to be prioritized. For example, public safety or environmental protection may be more important than cost or even functionality. Decisions on priorities can then guide tradeoff choices.
Improving designs at the high school level may involve sophisticated methods, such as using computer simulations to model proposed solutions. Students are expected to use such methods to take into account a range of criteria and constraints, to try and anticipate possible societal and environmental impacts, and to test the validity of their simulations by comparison to the real world.
Evaluate a Solution to a Real World Problem is a performance expectation related to Engineering Design HS-ETS1.
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.
Evaluating potential solutions-In their evaluation of a complex real-world problem, students: Generate a list of three or more realistic criteria and two or more constraints, including such relevant factors as cost, safety, reliability, and aesthetics that specifies an acceptable solution to a complex real-world problem; Assign priorities for each criterion and constraint that allows for a logical and systematic evaluation of alternative solution proposals; Analyze (quantitatively where appropriate) and describe* the strengths and weaknesses of the solution with respect to each criterion and constraint, as well as social and cultural acceptability and environmental impacts; Describe possible barriers to implementing each solution, such as cultural, economic, or other sources of resistance to potential solutions; and Provide an evidence-based decision of which solution is optimum, based on prioritized criteria, analysis of the strengths and weaknesses (costs and benefits) of each solution, and barriers to be overcome.
Refining and/or optimizing the design solution: In their evaluation, students describe which parts of the complex real-world problem may remain even if the proposed solution is implemented.