The book Chemistry on a Budget contains inexpensive chemistry labs that are useful with easy to obtain materials.
The early labs include the topics of Significant Figures, Density (3 labs), the Separation of a Mixture (including coverage of Percent Composition), and Liquid Chromatography. These are safe labs that cover essential information, giving you time to emphasize Lab Safety and get Lab Safety Contracts signed.
There are two versions of each lab, one with a ten-question conclusion and one with directions for a full lab report. This way the teacher has the option! Each lab is two pages to allow for one two-sided handout.
You can buy this lab book for $23 at amazon.com or lulu.com. It will take 1-2 weeks to get to you -- Order Now. It’s a great resource!
*Some of you have already purchased my lab book – be sure to check out Page 141 !
Here’s a list of past blog posts that may be useful at this time of year. They are grouped in various topic “themes”:
Measurement and Significant Figures
08/24/2014 SI System & Scientific Notation
08/19/2014 Measurement and Significant
Density and Dimensional Analysis
09/02/2014 Dimensional Analysis or The
In the 1980s there was concern about the layer of ozone (O3) in the atmosphere depleting. Why is atmospheric ozone important?
“Ozone is a gas made up of three oxygen atoms (O3). It occurs naturally in small (trace) amounts in the upper atmosphere (the stratosphere). Ozone protects life on Earth from the Sun’s ultraviolet (UV) radiation. In the lower atmosphere (the troposphere) near the Earth’s surface, ozone is created by chemical reactions between air pollutants from vehicle exhaust, gasoline vapors, and other emissions. At ground level, high concentrations of ozone are toxic to people and plants.”
Here is another source that provides background about ozone:
Notice the use of the term allotrope when discussing the O3 molecule.
“The ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet (UV) radiation. It contains high concentrations of ozone (O3) in relation to other parts of the atmosphere, although still small in relation to other gases in the stratosphere. The ozone layer contains less than 10 parts per million of ozone, while the average ozone concentration in Earth's atmosphere as a whole is about 0.3 parts per million.”
“The ozone layer can be depleted by free radical catalysts, including nitric oxide (NO), nitrous oxide (N2O), hydroxyl (OH), atomic chlorine (Cl), and atomic bromine (Br). While there are natural sources for all of these species, the concentrations of chlorine and bromine increased markedly in recent decades because of the release of large quantities of man-made organohalogen compounds, especially chlorofluorocarbons (CFCs) and bromofluorocarbons.”
“… in the early 1980s, through a combination of ground-based and satellite measurements, scientists began to realize that Earth’s natural sunscreen was thinning dramatically over the South Pole each spring. This large, thin spot in the ozone layer came to be known as the ozone hole.”
“It turned out that chlorofluorocarbons (CFCs)—long-lived chemicals that had been used in refrigerators and aerosols sprays since the 1930s—had a dark side. In the layer of the atmosphere closest to Earth (the troposphere), CFCs circulated for decades without degrading or reacting with other chemicals… In the upper stratosphere (beyond the protection of the ozone layer), ultraviolet light caused CFCs to break apart, releasing chlorine, a very reactive atom that repeatedly catalyzes ozone destruction.”
From an article published July 7, 2016, “[t]he hole in the ozone layer was first discovered in 1985 by scientists from the British Antarctic Survey, who described how ozone levels above the Antarctic were steadily dropping compared to the previous decade. This was quickly recognised as a severe environmental problem – and the culprit was identified as the unchecked use of chlorofluorocarbons, or CFCs.
Soon after, the Montreal Protocol banning the use of CFCs was signed and came into effect in 1989. Now, 27 years later, we have published evidence that shows the ozone hole is beginning to close.”
“[R]esearchers tracked the yearly opening of the Antarctic ozone hole in the month of September from 2000 to 2015, through measurements taken from weather balloons and satellites. They also tracked sulfur dioxide emitted by volcanoes, which can enhance ozone depletion, and temperature and wind, which can shift the ozone hole back and forth.
Compared with model simulations that predict ozone levels based on the amount of chlorine present in the atmosphere from year to year, the team found that the ozone hole had shrunk by more than 4 million square kilometers in 2015 from its peak size in 2000. More than half the shrinkage was deemed to be the result of reduction in atmospheric chlorine.”
If chlorine levels continue to reduce from the atmosphere at the current rate, the ozone hole could close permanently by mid-century.
One interruption to this ozone recovery was found with volcanic eruptions. “Large volcanic eruptions spew hundreds of thousands of tons of sulfur dioxide into the atmosphere, which reacts with water vapor to form sulfate aerosols. Along with slightly cooling the planet, these sulfur aerosols provide a surface on which ozone-destroying chemical reactions happen. This phenomenon was well documented after every major volcanic eruption, including those of Mount Pinatubo in 1991 and Mexico’s El Chichón in 1982.”
Here’s another useful article that summarizes the issue of ozone depletion, the response to ban CFCs, and the observation of recovery approximately 30 years later.
*This Blog contains several entries that would be helpful to your chemistry classroom. Check out the Topic List to help you to find past Blog entries.
Also, Write To Me about your successes, challenges, or questions in the Chemistry Classroom.
Remember, buying a copy of the lab book Chemistry on a Budget can be very useful to your Chemistry classroom with labs and class article ideas.
Have a great weekend!