observable

Examples of observable in the following topics:

• The Uncertainty Principle

  • Historically, the uncertainty principle has been confused with a somewhat similar effect in physics, called the observer effect, which notes that measurements of certain systems cannot be made without affecting the systems.
  • Heisenberg offered such an observer effect at the quantum level as a physical explanation of quantum uncertainty.
  • The uncertainty principle actually states a fundamental property of quantum systems and is not a statement about the observational success of current technology.
  • It must be emphasized that measurement does not mean only a process in which a physicist-observer takes part, but rather any interaction between classical and quantum objects regardless of any observer.
  • Since the uncertainty principle is such a basic result in quantum mechanics, typical experiments in quantum mechanics routinely observe aspects of it.

• Glow of Space Shuttles

  • The glow observed as a space shuttle re-enters the atmosphere is due to excited NO2 releasing light to return to its ground state.
  • When space shuttles return from space and being to re-enter the Earth's atmosphere, a glow, especially around the tail end of the shuttle, can often be observed.
  • Recall that excited-state nitrogen dioxide is responsible for the glow observed as space shuttles re-enter Earth's atmosphere.

• Introduction to Intermolecular Forces

  • The molecule is the smallest observable group of uniquely bonded atoms that represent the composition, configuration and characteristics of a pure compound.
  • Since all observable samples of compounds and mixtures contain a very large number of molecules (ca. !

• Spin-Spin Splitting

  • This is usually observed if the spin-coupled nuclei have very different chemical shifts (i.e.
  • Thus, when the perturbing nucleus becomes the observed nucleus, it also exhibits signal splitting with the same J.
  • They may actually be spin-coupled, but the splitting cannot be observed directly.
  • Longer-range coupling may be observed in molecules having rigid configurations of atoms.
  • The magnitude of the observed spin-splitting depends on many factors and is given by the coupling constant J (units of Hz).

• Precipitation Reactions

  • Aqueous silver nitrate (AgNO3) is added to a solution containing potassium chloride (KCl), and the precipitation of a white solid, silver chloride (AgCl), is observed:
  • Observing precipitation reactions can be useful in the laboratory to determine the presence of various ions in solution.
  • For instance, if silver nitrate is added to a solution of an unknown salt and a precipitate is observed, the unknown solution might contain chloride (Cl-).

• Emission Spectrum of the Hydrogen Atom

  • All observed spectral lines are due to electrons moving between energy levels in the atom.
  • Typically, one can only observe these series from pure hydrogen samples in a lab.
  • Lines outside of the visible spectrum typically cannot be seen in observations of sunlight, as the atmosphere absorbs most infrared and ultraviolet wavelengths through the action of water vapor and ozone molecules respectively.
  • Some of the most common and readily observable series have been named as shown in this image, where n1 is the ground state and n2 are excited states.

• Optical Activity

  • A sample cell holder is located in line with the light beam, followed by a movable polarizer (the analyzer) and an eyepiece through which the light intensity can be observed.
  • The observed rotations (α) of enantiomers are opposite in direction.
  • To be absolutely certain whether an observed rotation is positive or negative it is often necessary to make a second measurement using a different amount or concentration of the sample.
  • Thus it is common practice to convert the observed rotation, α, to a specific rotation, [α], by the following formula:
  • A 50:50 mixture of enantiomers has no observable optical activity.

• Experimental Determination of Reaction Rates

  • There are two main ways to measure the concentrations of reactions: by measuring the changes in an observable physical property, or by taking samples of the reaction solution and measuring concentration directly.
  • By Beer's law, the absorbance of the solution is directly proportional to the concentration of the C60O3 in solution, so observing the absorbance as a function of time is essentially the same as observing the concentration as a function of time.
  • The absorbance is proportional to the concentration of the C60O3 in solution, so observing the absorbance as a function of time is essentially the same as observing the concentration as a function of time.

• Reactions of Aromatic Compounds

  • The electrons in the pi system of the benzene ring are responsible for the reactivity observed.
  • A number of patterns have been observed regarding the reaction of substituted benzene rings.
  • These observations have been generalized to provide a predictive rule for electrophilic aromatic substitutions.

• Physical and Chemical Properties of Matter

  • Physical properties are properties that can be measured or observed without changing the chemical nature of the substance.
  • You can observe its mass by feeling how heavy it is when you try to pick it up; you can observe its volume by looking at it and noticing its size.