Saturday, February 1, 2014

This Day in Science History - February 1 - Emilio Segré

February 1st is Emilio Segré's birthday. Segré was an Italian physicist who discovered the first artificial element. He was visiting the University of California, Berkeley's radiation laboratory when he was given a sample of molybdenum that had been a target in the University's cyclotron that appeared to emit radiation from an unknown source. Segré identified the source of the radiation as an unknown element. The new element was named technetium after the artificial method it was created.

Segré also discovered the element astatine and co-discovered the antiproton with Owen Chamberlain. The discovery of the antiproton would earn both men the 1959 Nobel Prize in Physics.

Elements in the Human Body Infographic

Did you know 96% of your body mass consists of just 4 elements or that your body consists of 50-75% water? Here's a look at the elemental chemical composition of the human body. You are welcome to download and print the infographic.
Elements in the Human Body Infographic (Anne Helmenstine)

Chlorine Bleach Shelf Life

Bleach is one of those household chemicals that loses its activity over time. It doesn't matter whether or not the bleach container has been opened or not. Temperature is the primary factor affecting how long bleach remains active.
                                       According to Clorox™
, the amount of hypochlorite that is added to their bleach depends on the season in which it is manufactured, because temperature affects the decomposition rate of sodium hypochlorite. So, more hypochlorite is added to bleach made in the summer than in cooler months. Clorox aims to maintain a 6% hypochlorite concentration for at least six months after the manufacturing date, assuming the bleach is stored around 70°F. It takes about 4-8 weeks from the time chlorine bleach is made to when it gets to a store so that you can buy it to take home. This leaves you 3-5 months where the bleach is at the effectiveness level stated on its label.

Does this mean bleach is useless after 3-5 months? No, because you probably don't need 6% hypochlorite for laundry and home disinfection. The 6% hypochlorite level is an EPA disinfection standard. If you store your bleach where it can get warmer than 70°F... like 90°F... the bleach is still effective for around three months.

So, when you buy a bottle of bleach, it has a shelf life. The bleach will be highly effective for around 6 months and fine for home use for around 9 months. If you're like me and have had the same bottle for a couple of years, it's probably time to go shopping.

Hot and Cold Valentine Chemistry Demonstration

Try the hot and cold Valentine's Day science demonstration. (Getty Images)
Here's a fun and easy Valentine's Day chemistry demonstration. Take a pink liquid, heat it up and watch it turn colorless. Upon cooling, the color of the liquid will return to pink. Here's what you do:

Prepare the Hot and Cold Valentine Solution

Add a few drops of phenolphthalein indicator and a drop of concentrated ammonia to 500 ml of water in a beaker, flask or large test tube.

Perform the Valentine's Day Demo

Present the pink solution. You can heat the liquid over a hot plate or, in the case of the test tube, in a burner flame. Heating the solution causes a shift in the equilibrium between the unionized ammonia and the ionized ammonium hydroxide. The change in pH makes the pink-colored indicator turn colorless. If you do not experience a color change, there is too much ammonia in the solution, so dilute it further with water and try again.

How To Convert Between Degrees Fahrenheit and Celsius

Converting between Fahrenheit and Celsius temperature scales is useful if you are working temperature conversion problems, work in a lab, or simply want to know how hot or cold it is in a country that uses the other scale! It's easy to make the conversion. One way is to look at a thermometer that has both scales and simply read the value. If you're doing homework or need to do a conversion in a lab, you'll want the calculated values. You can use an online temperature converter or else do the math yourself. Here's what you do:

Celsius to Fahrenheit Degrees

F = 1.8 C + 32
  1. Multiply the Celsius temperature by 1.8.
  2. Add 32 to this number.
  3. Report the answer in degrees Fahrenheit.
Example: Convert 20°C into Fahrenheit.
  1. F = 1.8 C + 32
  2. F = 1.8 (20) + 32
  3. 1.8 x 20 = 36 so F = 36 + 32
  4. 36 + 32 = 68 so F = 68°F
  5. 20°C = 68°F


Wednesday, January 29, 2014

This Day in Science History - January 29 - Haber-Bosch Process

January 29th marks the passing of Fritz Haber. Haber was a German chemist who discovered a process to create ammonia from atmospheric gases. The Haber-Bosch process is a reaction that fixes nitrogen to form ammonia (NH3) from nitrogen gas (N2) and hydrogen gas (H2) under pressure over an iron catalyst. Haber discovered the process on a laboratory scale using table top equipment. German chemical engineer Carl Bosch converted the laboratory equipment to be used on large scale industrial equipment. This process was important in the production of agricultural fertilizers to replace the guano industry of South America. During World War I, the process was important to Germany for the production of munitions and explosives.

The process would earn both Haber and Bosch Nobel Prizes in Chemistry (1918 and 1931 respectively). Today, the Haber-Bosch process accounts for 100 million tons of fertilizer per year.

Physical and Chemical Changes Quiz

How well can you distinguish between physical and chemical changes? Physical changes involve a change in the form of a substance, but it remains the same on the molecular level. On the other hand, chemical changes involve chemical reactions. New products are created, often accompanied by changes in temperature or color. Melting the wax of a candle is an example of a physical change. The wax only changes shape -- it's still wax. Burning a candle is a chemical change. The wax undergoes a chemical reaction, producing carbon dioxide and water. Do you think you understand? Here's a quick self-test you can take to check whether you can tell the two types of changes apart... Try the quiz

Tuesday, January 28, 2014

Are Olympic Medals Real Gold?

The design of the Olympic medals changes for every Olympics, plus each host city gets to mint the medals, but the chemical composition of the medals is regulated so that there is not too much variation in the value from one Olympics to the next. While the Olympic gold medals do contain pure gold, do you know if they are solid gold or plated gold? Are plated medals plated with real solid gold, or with 14k or 18k gold or something else?.
Question: Are the Olympic Gold Medals Real Gold?
You can tell the Olympic gold medals are colored like gold, but are they solid gold or even real gold? Here's the answer to the question.
Answer: At one time, Olympic gold medals were real solid gold. However, the last time a solid gold medal was awarded was at the 1912 Stockholm Olympics. Modern Olympic gold medals are sterling silver that has been plated with real solid gold.

Gold Medal Regulations

The National Olympic Committee (NOC) allows quite a lot of leeway in the production and design of Olympic medals, but there are some rules and regulations that they impose. Here are the rules for gold medals:

This Day in Science History - January 28 - Kathleen Yardley Lonsdale

January 28th is Kathleen Yardley Lonsdale's birthday. Lonsdale was a leading figure in the field of crystallography. She began her work in the laboratory of William Bragg developing the techniques of x-ray crystallography. Her early work centered on simple molecules and branched into more complex organic compounds. She was the first to verify the shape of the benzene molecule. She showed the six carbon atoms that make up benzene were laid out in a flat hexagon.

Her later research involved x-ray crystallography of pharmaceuticals and other biochemical compounds. The Royal Society elected her as their first female Fellow in 1945 to honor her work.

10 Ways to Impress a Science Fair Judge

I'm talking about making a positive impression... there are lots of ways you can make a negative impression on a science fair judge. If that's your goal, turn in a poster with breakfast stains on it, which describes a project totally unrelated to science that you started on the way to school that day. On the other hand, if you are doing a science fair project and want to win an award or get a good grade, here are the types of things a science fair judge.

Monday, January 27, 2014

This Day in Science History - January 27 - Iodized Salt

January 27th marks the passing of David M. Cowie. Cowie was a medical researcher who was instrumental to the addition of iodine in table salt in the United States. Cowie was investigating the high incidents of goiter in the United States Great Lakes and Pacific Northwest areas. Goiter is a swelling of a thyroid gland in the neck and was recognized as a national health problem during the draft preceding World War I. Several young men were disqualified from service because of the condition.

The main reason for the development of goiter is the lack of iodine in a person's diet. The amount of iodine necessary to ward off these effects was very small and finding an effective means to administer iodine to people was needed. Cowie was aware of a Swiss process of adding sodium iodide to table salt (sodium chloride) and managed to convince Michigan salt producers to include minute quantities of sodium iodide to their salt for consumption locally. This type of salt was identified by the label "contains .01 per cent sodium iodide". In less than a year, the Morton Salt Company was distributing iodized salt nationally.

How to Balance Chemical Equations

Learning how to balance chemical equations is an essential skill for chemistry class or work in chemistry. Mastering this skill takes practice. Here are some resources that show you, in written and video tutorial form, how to balance equations, some examples of balanced equations and a printable practice sheet so you can see if you understand the concepts.

Balancing Chemical Equations

A chemical equation describes what happens in a chemical reaction. The equation identifies the reactants (starting materials) and products (resulting substance), the formulas of the participants, the phases of the participants (solid, liquid, gas), and the amount of each substance. Balancing a chemical equation refers to establishing the mathematical relationship between the quantity of reactants and products. The quantities are expressed as grams or moles.

How Well Do You Know Your Chemistry Glassware?

Here a Lytro light field photo of chemistry glassware for you. Good glassware is important for a positive outcome in the lab. Poor glassware will break when exposed to temperature extremes or even while mixing chemicals and may not indicate accurate volume measurements. When you're buying glassware, look for borosilicate glass. This glass becomes brittle with time and use, so it's best to get new glass if you can afford it. It's also important to get the right glassware for your purpose. This image shows a few staples of the chemistry lab. Can you name them?

Make Purple Gold

Colored gold alloys are seen in jewelry and gold is often added to glass to give it color (e.g., ruby glass), but this project is a little different. You'll be performing any of a number of chemical reactions to make a gold chloride solution turn purple.

What You Do

  • Mix together a dilute gold chloride solution (0.01%) and a 1% Rochelle salt (potassium sodium tartrate) solution. It's best if you use distilled water to prepare your solutions, as contaminants in tap water may affect your results.
  • Another option is to make "Purple of Cassius". This is a purple gold made by introducing tin to a very dilute gold solution. The author of the article posted at The Alchemy Website attempted to produce this color by reacting a dilute solution of gold chloride with stannous chloride. He obtained an amber solution, but not the desired purple coloration.
  • Gold may be reduced using formaldehyde. Add some sodium bicarbonate to a gold chloride solution to make the solution alkaline before introducing a drop of formalin.
  • Another recipe calls for add a few milliliters of gold chloride to boiling water and then adding some 1% tri-sodium citrate and boiling the solution until the desired color is produced. This colloidal solution is best kept in a shady location, as it is said to be photoreactive.
  • In general, gold chloride solution is photoreactive, so you could soak a filter paper with the solution and expose it to sunlight to seek a color change.
Alchemy is an experimental venture, so if you're interested in making purple gold, get out there and try some projects. Keep good notes and if you see good (or otherwise interesting) results, post specific instructions for other inquisitive people to try

Sunday, January 26, 2014

This Day in Science History - January 26 - Jenner and Cowpox Vaccine

January 26th marks the passing of Edward Jenner. Jenner was the English physician who noticed milk maids who had been infected with cowpox seemed to never contract the more serious disease, smallpox. Smallpox kills a third of the people who contract the disease, but if a person survives smallpox, they never catch it again. Variolation was the predominant smallpox treatment of the time. Variolation is when healthy people are exposed to a disease in hopes of giving them a milder (survivable) case of the disease. Between 2 and 3% of people exposed to variolation died.

Dr. Jenner tried a different route. He collected the pus from a cowpox sore on a milk maid and injected it into a young boy. He developed cowpox but quickly got over it. A couple weeks later Jenner exposed the boy to smallpox. He did not develop the disease. Jenner called his treatment a vaccine, from the Latin 'vaca', which means 'cow'. This treatment quickly became a standard treatment and is used for many different diseases.

How to Make a Glowing Flower

Cut flowers are beautiful and they still smell lovely when you turn out the lights, but don't you wish the flowers would stay beautiful in the dark? Well, they can! There is more than one way to make a glowing flower. Also, there are some hoaxes out there on the internet about how to make flowers glow, so I'll steer you clear of those.


Glowing Flower - Method #1

  1. Test a highlighter pen to make sure it glows under black (fluorescent) light. Yellow is reliable, but some other colors glow brightly, too.
  2. Use a knife or saw to cut open the pen and expose the fibers which contain the ink. Remove the ink strip.
  3. Squeeze dye from the ink pad into a small amount of water.
  4. Trim the end of a flower so that it will be able to take up water. Place the flower in the water with the ink.
  5. Allow several hours for the flower to absorb the fluorescent ink. When the flower has taken in the ink its petals will glow under black light.

DRY MIX Helps Keep Experimental Variables Straight

Do you have trouble remembering which variable goes on the x-axis and which goes on the y-axis when you plot your experimental data? There's a handy acronym called DRY MIX that can help you keep it straight.

You control and measure variables in an experiment and then record and analyze the data. There is a standard way to graph the data, with the independent variable on the x-axis and the dependent variable on the y-axis. How do you remember what independent and dependent variables are and where to put them on the graph? There is a handy acronym: DRY MIX
D = dependent variable
R = responding variable
Y = graph information on the vertical or y-axis
M = manipulated variable
I = independent variable
X = graph information on the horizontal or x-axis
The dependent variable is the one being tested. It is called dependent because it depends on the independent variable. Sometimes it is called the responding variable.
The independent variable is the one you change or control in an experiment. Sometimes this is called the manipulated variable or the "I do" variable.
There may be variable that don't make it onto a graph, yet can affect the outcome of an experiment and are important. Controlled and extraneous variables aren't graphed. Controlled or constant variables are ones you try to keep the same (control) during an experiment. Extraneous variables are unanticipated or accidental effects, which you didn't control, yet which might influence your experiment. Although these variables aren't graphed, they should be recorded in a lab book and report.

How To Make Hydrogen Gas

Hydrogen is one of the easiest gases to prepare. You can do it at home, using water! The easiest method uses electricity from a battery to split water, H2O, to release hydrogen gas, H2. This electrolysis method can be improved several ways, plus there are several other reactions that produce hydrogen... Learn how

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