Main Pages

The Game of Poisons

Book Reviews
Links & Comments

Chem 534


Monthly Question

Crystal Ball

Solutions to 1999 Monthly Puzzles

  • January 1999: Colours in Space
  • February 1999: An Ill-Advised Demonstration
  • March 1999: Vitamin Supplements Versus Natural Ones
  • April 1999: To See the World In a Grain Of Snow
  • May 1999: Olber's Paradox: Should the Night Sky Be Dark?
  • June1999: How toTell Vodka From Water Without Taste, Sight and Smell?
  • July1999: A Downhill Question
  • August 1999: Exotic Nuclei
  • September 1999: Hats Off to Minnesotans
  • October 1999: Hydrogen's True Colours
  • November 1999: Cooking with Potatoes and Liver
  • December 1999: Atomic Spin

  • Solutions to 2007 Questions
  • Solutions to 2006 Questions
  • Solutions to 2005 Questions
  • Solutions to 2004 Questions
  • Solutions to 2003 Questions
  • Solutions to 2002 Questions
  • Solutions to 2001 Questions
  • Solutions to 2000 Questions
  • Solutions to 1999 Questions
  • Solutions to 1998 Questions
  • Solutions to 1997 Questions
  • Solutions to 1996 Questions
  • Questions Sorted By Topic

  • Solution to January 1999 Puzzle of the Month

    The question was:

    Why are so many nebulae red?


    To begin with, we have to realize that the light from nebulae is too dim for colours to be seen, even through telescopes. The red and other colours only appear in photographs after the film has been exposed for several hours.

    A nebula is, pardon the pun, a nebulous term. It can refer to different astronomical phenomena. Some nebulae like the Orion nebula are regions where stars are being formed. As this happens, UV light is released and is absorbed by hydrogen atoms in the dust clouds surrounding young stars. The energy causes the electron in each atom to jump to a higher energy level. Upon returning to a lower level, energy is emitted in the form of visible light. Although the emissions are not always of the same frequency, only a few colours of specific wavelengths ( red, blue-green and blue) are emitted, because the number of energy levels of electrons are limited. As a result we see a reddish or puplish ( red + blue) colour in pictures of nebulae.

    Solution to February 1999 Puzzle of the Month

    The question was:

    A teacher decides to demonstrate the softness of sodium by sticking a spatula into a small Na cube. Then to demonstrate sodium's reactivity towards water, he carelessly adds the sodium and the spatula into a beaker of water. Why is this a dangerous demonstration, more hazardous than the normal reaction between water and sodium?


    Normally , if sodium is simply dropped in water the hydrogen released by the reaction keeps the sodium afloat. Less of the metal reacts with water instantaneously, and thus although one still has to be careful , a small piece leads to a controlled and generally safe experiment. But by sticking a spatula into the sodium, the combined density is too high for the sodium to remain buoyant. More surface is exposed, more energy and hydrogen are released, and the sudden increase in pressure and temperature can easily shatter the beaker, leading to a violent explosion and fire.

    Solution to March 1999 Puzzle of the Month

    The question was:
    Are fresh fruits and vegetables a better alternative to Vitamin pills?


    Synthetic vitamins are chemically identical to their natural counterparts. But there is more to it than that.

    For example,synthetic vitamin C supplements are equally effective in preventing scurvy and in acting as a catalyst for the previously mentioned physiological processes. These facts, however, do not exclude the possibility that other compounds found in fruit and not in supplements help accentuate some of Vitamin C' s functions. In Schwartz's March 7 1999 column for the Montreal Gazette, he cites a Cornell study ( no exact reference given , unfortunately) which clearly showed that vitamin C as an integral part of fruit juices was more effective in reducing the formation of carcinogenic nitrosamines in the body than when taken as a supplement. Chlorogenic acid ( C16H18O9 ), supposedly boosts vitamin C activity.
    The Merck Index describes chlorogenic acid as an important factor in plant metabolism. Chlorogenic acid and two of its isomers occur in leaves, fruits and other tissues of dicotyledenous plants (Most commonly eaten fruit are dicots). Like vitamin C, it is a reducing agent . It has long been known as the compound that causes potatoes to blacken when they are cut and exposed to air. (Chem. & Ind. (London) 1958,627) So it is not surprising that it too would attack electron-seeking free radicals. The Vitamin C-chlorogenic acid teamwork reminds us of how numerous carotenoids assist Vitamin A in its physiological role.

    Solution to April 1999 Puzzle of the Month

    The question was:

    Describe the flurry of molecular events that occurs when granular snow is dropped into a puddle of muddy water.


    The water molecules in the puddle are rotating and vibrating. Upon colliding with the granular snow crystals, the liquid molecules transfer some of their energy to the solid, causing their vibrational energy to increase to the point that some of the molecules begin to rotate. At this point some of the snow has melted. At the same time, some of the water and mud particle suspension slips inside the crystal structure of the granular snow, displacing the air within it and causing the snow to turn from white to brown.

    Solution to May 1999 Puzzle of the Month

    The question was:

    Why is the sky dark at night? After all, doesn't every line of sight eventually lead to the surface of a bright star? And even if the starlight of distant stars gets absorbed by dust in the way, shouldn't that dust eventually glow? Explain.


    The sky would be bright at night if the universe was both infinitely large and infinitely old. With no limit to the number of stars, then every point in the sky would be on a line to a galaxy. With all the time in the world, either the galaxy's light or its effect on interstellar dust would have reached our planet. This is known as Olber's paradox.

    But in an expanding universe, the density of galaxies is low enough that most our sight-lines do not cross any stars.

    Solution to June 1999 Puzzle of the Month

    The question was:

    You're in the kitchen with a glass of water and a glass of vodka. The problem is you cannot remember which is which. You have an awful cold and cannot smell them apart. Tasting them is out of the question because you absolutely hate vodka. How then do you tell them apart without smelling, tasting or weighing them---( since there is no balance in the kitchen)?


    Drop an ice cube in any one. If it floats, there's water in the glass. If it sinks, there's vodka because vodka's density is less than that of ice.
    When ice melts, the volume of water is less than that of ice. In addition, water bonds to alcohol in solution, so that the total volume of liquid water and vodka is less than the the sum of the individual volumes. This effect creates the impression that someone has been drinking from your unattended glass of vodka on rocks.

    Solution to July 1999 Puzzle of the Month

    The question was:

    A big plastic ball glistens in the sun. As the ball rolls down a small hill, does the bright spot appear to move up and down the ball? Why or why not?Solution:

    No. The sun is so far away that it can be safely assumed that its rays are parallel to each other. So relative to the rest of the ball, the glistening spot will appear to be motionless.

    Solution to August 1999 Puzzle of the Month

    The question was:

    On earth and in most of space, the neutron to proton ratio for most isotopes rarely exceeds 1.6. Under what conditions would this ratio be significantly surpassed?


    Neutron stars have nothing but neutrons in their cores, but their outer layers have protons as well. Because of the outstanding pressures within these collapsed stars, reverse beta decay reactions occur,

    p + e --> n

    and the atoms have more neutrons than are normally found in nuclei. More specifically, the outer crust, a region with a density of 1010 to 1014kg/m3, can produce80Zn and 118Kr, which have neutron to proton ratios of 1.67 and 2.27, respectively.

    Solution to September 1999 Puzzle of the Month

    The question was:

    For global warming scenarios of the next three decades, which latitudes are expected to experience temperature increases that will be at least twice the global average increase?


    Greenhouse gases such as CO2 and CH4 will raise global averages by 1.5 to 4 oC, but mid latitudes will experience twice that average.By the year 2030, for instance, Minneapolis might approach winter averages of above 0oC. (Global Climatic Change, Scientific American, April 1989) Their 1970's winter average temperature was -7 oC

    Solution to October 1999 Puzzle of the Month

    The question was:

    Why does the spectrum of hydrogen feature four thin coloured lines ( red, blue-green, blue and violet) ?


    When hydrogen gas absorbs energy, be it in the form of electricity or UV light, the lone electron jumps from a lower energy level to one of 6 higher levels. If an excited electron jumps to the third energy level and falls back to the second, it will emit energy corresponding to the difference between the two levels. That difference happens to be of a frequency visible to the naked eye: red. An electron falling from the fourth to the second level emits more energy and it happens to correspond to the frequency of green light. Blue results from a fall of the 5th to the 2nd, and violet, from the 6th to the 2nd. The electron eventually falls from the second to the first level, but that fall does not correspond to a visible wavelength. For a good visual explanantion, see The Bohr Site. Because there are only a limited number of energy levels available, not all shades of those colours appear in hydrogen's spectrum. Thus the lines are very narrow, and certain colours of the rainbow such as yellow are missing entirely.

    Solution to November 1999 Puzzle of the Month

    The question was:

    If you add either a piece of potato or liver to hydrogen peroxide, it begins to fizz. What happens if you add peroxide to a boiled potato and, in a separate container, to boiled liver? Try it, and explain why.


    Hydrogen peroxide is a product of metabolism, meaning that it is naturally produced by both plant and animal cells alike. But contrary to the the beliefs of some faddists, what is natural is not always good for you, and peroxide because of its strong electron-stripping abilities must be reduced. Organisms break down hydrogen peroxide into oxygen and water with the help of an enzyme known as catalase. But the plant and animal versions of the enzyme are not alike. The animal versions are less sensitive to heat and will continue to break down peroxide after they've been placed in boiling water. That kind of heat denatures plant catalases, so that a boiled potato will no longer make peroxide fizz.

    Solution to December 1999 Puzzle of the Month

    The question was:

    A question from student Alec Sweet: Atomic particles are said to have spin. What does that imply?


    A good explanation for electron spin is provided by
    Spin is an intrinsic property of an electron, like its mass or charge. In elementary treatments, spin is often visualized as an actual spinning motion. However, it is a quantum mechanical property without a classical counterpart, and to picture spin in this way can be misleading. Nevertheless, for the present discussion, such a picture is useful. An electron has a fixed amount of spin, in the sense that every electron in the universe is continually spinning at exactly the same rate. Although the spin of an electron is constant, the orientation of the axis of spin is variable, but quantum mechanics restricts that orientation to only two possibilities. The two possible spin states of an electron are represented by the arrows and and are distinguished by the spin magnetic quantum number, ms, which takes the values +1/2 (for the spin) or -1/2 (for the spin). Because of its spin, an electron must obey a fundamental requirement known as the Pauli exclusion principle. This principle (which is a consequence of the more fundamental Pauli principle; see the article atom: Electrons) states that no more than two electrons may occupy a given orbital and, if two electrons do occupy one orbital, their spins must be paired (denoted ; that is, one electron must be and the other must be ). The Pauli exclusion principle is responsible for the importance of the electron pair in the formation of covalent bonds. It is also, on a more cosmic scale, the reason why matter has bulk; that is to say, all electrons cannot occupy the orbitals of lowest energy but are instead located in the many shells that are centred on the nucleus. Also owing to the existence of spin, two objects do not simply blend into one another when they are in contact; the electrons of adjacent atoms cannot occupy the same space, thereby prohibiting the combining of two atoms into one. Here again is an example of a seemingly trivial property, in this case spin, having consequences of profound and macroscopic importance. In this instance, the spin of the electron is responsible for the existence of identifiable forms of matter.

    Your Science Home

    Page Maintained by E. Uva


    Copyright UVA@LHAŠ 2014