07/06/2014 Decorating Your Classroom
07/13/2014 Chemistry Laboratory Safety
07/20/2014 Classroom Grading Programs
07/27/2014 Classroom Ideas –Daily Announcements
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08/03/2014 Lab Report Help
08/28/2016 The First Days of School
The book Chemistry on a Budget contains inexpensive chemistry labs that are useful with easy to obtain materials.
It will take a few weeks for the book to get to you, so ORDER NOW! You’ll want to have some time before the school year starts to see how you can use the book Chemistry on a Budget in your class.
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.
*Some of you have already purchased Chemistry on a Budget – be sure to check out Page 141 !
“As clocks across France struck midnight on 1 July  they heralded the end of the kilogram as we know it. Until that moment, scientists could submit measurements that will be used to redefine four of the seven base units: the kilogram, the ampere, the kelvin and the mole. Next year, this work will end the rule of the 128-year-old kilogram artefact and change the foundations of every mass measurement. …
The physical object representing the kilogram – the International Prototype of the Kilogram (IPK) also known more affectionately as le grand K – is a platinum–iridium cylinder manufactured in 1879 and chosen as the kilogram 10 years later. Only a few people have ever seen the big K; it sits under several nested bell jars in a triple-locked vault at the International Bureau of Weights and Measures (BIPM) in France next to six sister masses, all kept at constant temperature and humidity.”
"In the scientific community, kilograms have served as a nearly universal standard for over 200 years. 1799 saw the birth of the kilogram, initially defined as the mass of one liter of water at 4º C. This lasted for nearly a century, until scientists found themselves in need of a more stable unit for weight calibration.
The International Prototype Kilogram was crafted from platinum-idirium alloy and honed to perfection. To this day it remains locked in an environmentally controlled environment in Sèvres, France. Every 50 years the prototype emerges for comparison against its sister copies. The copies are used as models for a collection of replicas kept around the world.”
“The kilogram has the dubious distinction of being the only SI unit still based on a physical object; specifically, a metal cylinder kept in a vault in France. Plans are well underway to redefine the kilogram in mathematical terms instead, and to that end a team at the National Institute of Standards and Technology (NIST) has submitted a precise new calculation of a key formula.”
According to a 2009 article: “[a]s it stands, the entire world's system of measurement hinges on the cylinder. If it is dropped, scratched or otherwise defaced, it would cause a global problem. ‘If somebody sneezed on that kilogram standard, all the weights in the world would be instantly wrong,’ says Richard Steiner, a physicist at the National Institute of Standards and Technology (NIST) in Gaithersburg, Md.
For that reason, the official kilogram is kept locked inside a secured vault at the International Bureau of Weights and Measures near Paris. Scientists are so paranoid that they've only taken it out on three occasions: in 1889, 1946 and 1989. Each time, they've compared it to a set of copies. In 1889, the copies and the kilogram weighed the same, but by 1989, they had drifted apart. Based on the data, the kilogram appears to weigh slightly less than the copies.”
This issue has been discussed for the past 10 years.
From an article in 2007: “The official kilogram -- a cylinder cast 118 years ago from platinum and iridium and known as the International Prototype Kilogram or ‘Le Gran K’ -- has been losing mass, about 50 micrograms at last check. The change is occurring despite careful storage at a facility near Paris.
That's not so good for a standard the world depends on to define mass.
Now, two U.S. professors -- a physicist and mathematician -- say it's time to define the kilogram in a new and more elegant way that will be the same today, tomorrow and 118 years from now. They've launched a campaign aimed at redefining the kilogram as the mass of a very large -- but precisely-specified -- number of carbon-12 atoms.
‘Our standard would eliminate the need for a physical artifact to define what a kilogram is,’ said Ronald F. Fox, a Regents' Professor Emeritus in the School of Physics at the Georgia Institute of Technology. ‘We want something that is logically very simple to understand.’
Their proposal is that the gram -- 1/1000th of a kilogram -- would henceforth be defined as the mass of exactly 18 x 14074481 (cubed) carbon-12 atoms.”
“Why should we care whether a kilogram in a vault is ‘perfect’ or not? Because it’s bad news when your standard is no longer standardized. While no one’s worried whether a single kilogram of apples is a hair lighter or heavier at the produce stand, a small discrepancy can become a gargantuan one if you’re dealing with, say, a whole tanker of wheat. The kilogram is also used as a building block in other measurements. The joule, for instance, is the amount of energy required to move a one-kilogram weight one meter. The candela, a measure of the brightness of light, is measured in joules per second.”
Some past Measurement blog posts include:
08/19/2014 Measurement and Significant Figures
08/24/2014 SI System & Scientific Notation
09/02/2014 Dimensional Analysis or
The Factor-Label Method
*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.
Happy New School Year!