Physical Change
Physical Change - Related Videos
05:21
General Approach to the Physical Exam
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2023
Source: Jaideep S. Talwalkar, MD, Internal Medicine and Pediatrics, Yale School of Medicine, New Haven, CT The examination of the body is fundamental to the practice of medicine. Since the Roman Empire, physicians have described the connection between alterations in function of specific parts of the body and specific disease states and have sought to further scientific understanding to improve bedside diagnosis. However, in this modern age of increasing technology within medical diagnostics, it...
02:57
Physical and Chemical Properties of Matter
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2020
The characteristics that enable us to distinguish one substance from another are called properties. Physical Properties of Matter A physical property is a characteristic of matter that is not associated with a change in its chemical composition. Familiar examples of physical properties include density, color, hardness, melting and boiling points, and electrical conductivity. We can observe some physical properties, such as density and color, without changing the physical state of the matter...
08:14
Climate Change - Student Protocol
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2019
Melting Land and Sea Ice ExpandNOTE: This activity is a simulation of land- and sea-ice melting and their effects on water levels. First, label one graduated cylinder as 'Sea Ice' and the other graduated cylinder as 'Land Ice.' Hypotheses: the experimental hypothesis might be that the land ice melting will cause the water level to rise more than the melting sea ice. The null hypothesis would be that there will be no difference in the change in water level between the two containers. Add 10 ice...
04:34
Climate Change - Concepts
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2019
The certainty of climate change remains a public controversy despite the consensus among approximately 97% of active climate researchers, who not only agree that the Earth’s climate is changing but also state that this change is intensified by human activity, predominantly carbon emissions 1. The disconnect between the public and the experts is partly due to poor understanding of the mechanisms involved in climate change as well as the differences among essential concepts such as weather and...
01:26
Technological Change
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2024
Total Factor Productivity (TFP) measures the efficiency with which inputs are transformed into outputs in production. It is the essence of economic growth, driven by technological advancement. Consider the agricultural sector, where production requires vast amounts of human labor and work animals. Today, modern farm machinery and agriculture technologies have revolutionized how we cultivate crops and produce food much more efficiently. TP = A*f(K, L) TFP is represented as a multiplier 'A' in...
FAQs
Energy transfer, temperature, and phase behavior provide three linked ways to examine a physical change. A sample may move between phases as particle motion and spacing change, while its molecular identity remains preserved. Recording temperature alongside the observed state helps chemistry investigations describe the transition and distinguish a change in state from a change in composition.
To distinguish a physical change from a chemical reaction, focus on whether the substance’s chemical composition and molecular identity are preserved. Changes in form, state, or appearance can occur without producing a new molecular identity. This distinction prevents a visible transformation from being classified as a reaction solely because the sample looks different afterward.
Reversibility is useful evidence when interpreting a transformation, although it should be considered alongside composition and phase behavior. Melting and freezing illustrate how the same substance can shift between forms as particle motion and spacing change. The ability to return to the prior form supports analysis of the process as a nonreactive transformation.
Physical change supports several separation and purification methods, including filtration, distillation, crystallization, and chromatography. These approaches exploit differences in physical properties rather than changing the chemical identities of the substances. In chemistry, selecting among them allows a mixture or sample to be treated through a property-based process while preserving the substances’ molecular identities.
A basic chemistry workflow can follow the observed form or state, record temperature, and examine energy transfer and phase behavior. These observations connect what is visible to particle motion and spacing, while the preserved molecular identity provides a check that the investigation concerns a physical change rather than a chemical reaction.
Dissolving belongs in the study of physical change when the process rearranges particles without altering molecular identity. This perspective separates the act of dissolving from a chemical reaction and places it alongside melting, freezing, evaporation, and condensation as a way to examine how particle arrangement, motion, or spacing can change while composition is preserved.