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Saturday, May 3, 2014

How Mood Rings Work

One of the more popular beach accessories where I live is a mood toe ring. These are similar to the 1970s mood rings, except they are smooth bands of color instead of the classic rounded domes. Also, I've seen reddish tones in the newer rings that weren't available in the first rings. The original mood rings had a nasty habit of self-destructing if you got them wet, which I can verify isn't a problem with the modern rings.

Mood rings supposedly change color to show your emotions.

How a Baking Soda and Vinegar Volcano Works

The baking soda and vinegar volcano is a popular science project, but the science part of the project involves explaining how the reaction models a real volcano or explaining the science behind the reaction that produces the lava. In a nutshell, the reaction between baking soda and vinegar produces sodium acetate, water, and carbon dioxide. The carbon dioxide is trapped by detergent to form bubbly lava, which flows down the side of the model because carbon dioxide is more dense than air. However, sometimes you'll want to explain or write the chemical reactions that occur to produce the carbon dioxide. Here's a look at ways to write the reactions.

Glow in the Dark Geode

It's very easy to make a glow in the dark crystal geode. The 'rock' is a natural mineral (eggshell). You can use one of several common household chemicals to grow the crystals. The glow comes from paint, which you can get from a craft store.

Glow in the Dark Geode Materials
  • eggs
  • glow in the dark paint (I used GlowAway™ washable glowing paint)
  • very hot water (I used my coffee maker)
  • borax, alum, epsom salts, sugar, salt, or use another crystal recipe
  • food coloring (optional -- I used neon green coloring)
Prepare the Glowing 'Geode'
  1. There are two ways to crack your eggs. You can carefully crack the top of the egg by tapping it on a countertop. This will give you a deep geode with a smaller opening. Alternatively, you can crack the equator of the egg or carefully cut it with a knife. This will give you a geode you can open and put back together.
  2. Dump the egg or make scrambled eggs or whatever.
  3. Rinse out the inside of the eggshell with water. Peel away the interior membrane so you are left with only the shell.
  4. Allow the egg to air dry or carefully blot it dry with a paper towel or napkin.
  5. Use a paintbrush, swab, or your fingers to coat the inside of the eggshell with glowing paint.
  6. Set the painted egg aside while you mix the crystal-growing solution.
Make the Crystal Solution
  1. Pour hot water into a cup.
  2. Stir borax or other crystal salt into the water until it stops dissolving and you see some solid at the bottom of the cup.
  3. Add food coloring, if desired. Food coloring does not get incorporated into all crystals (e.g., borax crystals will be clear), but it will stain the egg shell behind the crystals, giving the geode some color.

This Day in Science History - May 2 - George Pimentel

May 2nd is George Pimentel's birthday. He was an American chemist who produced the first chemical laser. Chemical lasers rely on an exothermic reaction to pump the necessary energy to create the coherent light of a laser. They are some of the most powerful lasers in use today with outputs in the megawatt range. They are used as industrial cutting or drilling tools, research and military weapons. To give an idea of the power - energy per unit area - of these lasers, the laser in your DVD player, computer mouse, or laser pointer has a power rating in the milliwatt range or 1/1000th of a watt. A megawatt laser is 1,000,000,000 or 1 billion times more powerful.

How Trick Candles Work

Trick birthday candles are the sort that mysteriously re-light themselves a few seconds after being blown out. If you put them on your birthday cake, especially if you are... how shall I put it... using lots of candles... then blowing out all of the candles at once can be a discouraging exercise.

Burning Driftwood - Pretty Fire, Pretty Toxic

Did you know you can burn driftwood, especially from the ocean, to get a fire with blue and lavender flames? The colored fire comes from excitation of the metal salts that have soaked into the wood. While the flames are pretty, the smoke given off of the fire is toxic. Specifically, driftwood releases a lot of dioxin from combustion of salt-soaked wood. Dioxins are carginogenic, so burning driftwood from beaches is not recommended. Some coastal communities have considered burn bans on driftwood to reduce the levels of pollution from the smoke. All smoke contains particulates which can cause health problems when the smoke is inhaled, but you may have been unaware of the additional issue with burning driftwood.

Friday, May 2, 2014

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Tuesday, April 29, 2014

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Solvent Effects and SN2 and SN1 reactions: Nucleop...

Solvent Effects and SN2 and SN1 reactions: Nucleophilic Substitution
SN2 reactions and solvent effects
Polar aprotic solvents – solvents that do not have acidic proton such as DMSO, DMF, CH3CN, HMPA - accelerate the rate of SN2 reactions by solvating the cation thus making the nucleophile more available to react.
On the contrary, protic solvents such as alcohols or amines decrease the rate of SN2 reactions since they tend to solvate nucleophiles (Fig. 1). The partial positive charge that exists in the O-H hydrogens solvate the negative charge of the nucleophile (Nu:-).Solvated nucleophiles are held tightly and are unable to react with the electrophilic substrates – compounds that have leaving group.
Fig. 1: Partially positively charged hydrogens from polar O-H bonds solvate partially negative charge of the nucleophile. Solvated nucleophiles – as the one shown above – are unable to react with electrophilic substrates.
The effect of solvents on the rate of SN2 nucleophilic substitution reactions is shown in Fig. 2.
Fig. 2: Solvents and SN2 reactions rates.
The same electrophile - especially compounds having a leaving group in a secondary carbon – can react under SN2 or SN1 conditions by simply changing the solvent and the nucleophile. Under SN2 conditions and when a chiral carbon exists an inversion is observed in the product while under SN1 conditions a racemic mixture is produced (Fig. 3).
Fig. 3: The secondary substrate shown above reacts with CN-- a strong nucleophile - in a polar aprotic solvent acetone underSN2 conditions giving an inverted product at the secondary carbon. The same substrate reacts with OH-- a weak nucleophile – in a polar protic solvent like methanol under SN1 conditions giving a racemic mixture.
SN1 reactions and solvent effects
SN1 reactionsproceed more rapidly with more stablecarbocations, therefore the rate of reactivity is correlated to carbocation stability.Polar protic solvents, such as water and alcohols, organic acids and inorganic acids (H2SO4, H3PO4), stabilize the transition state by solvating the carbocation intermediate and therefore increase the reaction rate even more.
In general, polar protic solvents are able to solvate both cations and anions through hydrogen bonds. For example they dissolve salts such as NaBr by hydrogen bonding to the anion Br-and electron donation to the cation Na+.

Solvent Effects and SN2 and SN1 reactions: Nucleop...

Solvent Effects and SN2 and SN1 reactions: Nucleop...: S N 2 reactions and solvent effects Polar aprotic solvents – solvents that do not have acidic proton such as DMSO, DMF, CH 3...

Chemistry in our life: Loudspeakers in your window

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This lesson will introduce you the student to basic chemistry principles. An understanding of this basic information will allow you to learn the more advanced topics in your course lectures.
This lesson focuses on a number of areas related to basic Chemistry. You should review each page in order as they build upon one another. Many of these topics will be review. Others may be new to you. Either way you will learn the fundamentals of chemistry needed in this course.
Atoms are the basic unit of chemistry. They consist of 3 smaller things:
*.Protons- these are positively charged (+)
*.Electrons- these are negatively charged (-)
*.Neutrons- these have no charge
These 3 smaller particles are arranged in a particular way. In the center is theNucleuswhere you find the positive Protons and neutral Neutrons.
In orbit around the nucleus are the Electrons. These are found in a series of orbits (depending on the atom) with differing numbers of electrons as seen below.
Interaction of Atoms
It's the electrons in orbit around the nucleus that allow one atom to interact with other atoms so they can be linked together.
For example, H2O consists of an Oxygen atom linked to 2 Hydrogen atoms. The linkage or interaction between the electrons of the Hydrogen and Oxygen atoms is called a Chemical Bond. More on these later.
Atoms in the Human Body
The human body is made up of a couple dollars worth of chemicals.
The 12 most useful atoms for you to know about are listed below:
Sometimes atoms gain or lose electrons. The atom then loses or gains a "negative" charge. These atoms are then called ions.
*.Positive Ion- Occurs when an atomloses an electron(negative charge) it has more protons than electrons.
*.Negative Ion- Occurs when an atomgains an electron(negative charge) it will have more electrons than protons.
The following image shows Nalosingan electron and Clgainingan electron
*.Thus the Na becomes Na+
*.The Cl becomes Cl-
Here are some examples of common ions:

Chemistry in our life: Pi-stacking better without the aromatics?

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Monday, April 28, 2014

Analytics Blog: New: AdWords Reports for App download campaigns

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