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Definition of the kilogram just changed

5/31/2019

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The book Chemistry on a Budget contains inexpensive chemistry labs that are useful with easy to obtain materials.
 
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. 
 
A 5-Star Customer Review of Chemistry on a Budget at amazon.com states:

“[S]traight forward, to the point, using household chemicals… this is the lab book for you. 
I teach high school chemistry and this is exactly what I was looking for. Labs included simple household chemicals that could be easily found. Nice format, easy to follow along procedures, and touches on every topic of our chemistry curriculum.”
 
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!
 
http://www.amazon.com/Chemistry-Budget-Marjorie-R-Heesemann/dp/0578129159/ref=sr_1_1?s=books&ie=UTF8&qid=1389410170&sr=1-1&keywords=chemistry+on+a+budget

http://www.lulu.com/shop/marjorie-r-heesemann/chemistry-on-a-budget/paperback/product-21217600.html
 
*Some of you have already purchased my lab book – be sure to check out Page 141 !
 
 “…130 years after it was established, the kilogram as we know it is about to be retired. But it's not the end: …20 May 2019, a new definition will be put in place - one that's far more accurate than anything we've had until now.”
https://www.sciencealert.com/tomorrow-the-definition-of-the-kilogram-will-change-forever-here-s-what-that-really-means

“For example, a metre is determined by the distance light travels in a vacuum in 1/299792458 of a second. A second is determined by the time it takes for a caesium atom to oscillate 9,192,631,770 times.

A kilogram is defined by… a kilogram.

No, literally. It's a kilogram weight called the International Prototype of the Kilogram (IPK), made in 1889 from 90 percent platinum and 10 percent iridium, and kept in a special vault in the BIPM headquarters.

In fact, the kilogram is the only base unit in the SI still defined by a physical object.”

“The new definition of the kilogram, which was adopted at an international conference [in] … Versailles, France, went into effect Monday [05/20-19]. Instead of being based upon a shiny hunk of metal stored in a vault in Sevres, France, on the outskirts of Paris, the kilogram is now based on the Planck constant, a tiny, unvarying number that plays a key role in quantum physics. ...

The kilogram was redefined in order to create a precise, unchanging standard for its value, according to Henson. More than a century of cleanings and exposure to air had caused the original French prototype — known as the International Prototype of the Kilogram, or ‘Le Grand K’ — to lose about 50 micrograms. That’s roughly the mass contained within a handful of fingerprints. …

Since it’s based not on a physical object but on a mathematical constant, the new kilogram isn’t subject to such changes. And while 50 micrograms doesn’t sound like much, Jon Pratt, an engineer at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, said the more accurate definition would make a big difference for researchers working with tiny quantities of medications, radioactive compounds and other materials requiring nanoscale precision.

What will the new kilogram mean for the rest of us? Experts say not much. ‘You don’t need to panic,’ Henson said, adding that the switch had been designed to go unnoticed by most people. ‘Nothing is going to change.’

In other words, a kilogram of something at the store or on the scale will continue to be equivalent to about 2.2 pounds."
https://www.nbcnews.com/mach/science/definition-kilogram-just-changed-here-s-what-means-ncna1007731
 
 “Although the value of the kilogram will not change, the redefinition of the kilogram using a constant will ensure it remains reliable, and enable far more accurate mass measurements in the future.

The Planck constant describes the behavior of particles and waves on the atomic scale and depends on three units: the meter, kilogram and second. As the second and meter are measured and defined by the speed of light, they can be used with the fixed Planck constant to define a kilogram.
 
The Planck constant is, in turn, measured using an instrument known as the Kibble balance, first developed at NPL by the late physicist Bryan Kibble.

‘The redefinition of the kilogram is a tremendous leap for the international measurement community and science as a whole,’ said NPL fellow Ian Robinson, who worked on the device's development with Kibble... .

‘By using a universal constant of nature to define the kilogram we have enabled the whole world to contribute to the topmost level of mass measurement and, in addition, paved the way for future innovations. Much like upgrading a building's foundations, we're building a stable base for future science and industry.’ "
 
https://www.cnn.com/2019/05/20/world/new-kilogram-introduced-scli-intl-scn/index.html
 
You may want to use an article from those posted in this Blog have students write an Essay question for your Final Exam.

Past blog posts about Final Exams and the End of the School Year include:

06/08/2014            Final Exams – End of Year Preparation
06/15/2014            End of Year Activity – Lab Clean-Up
06/29/2014            Summer Vacation
05/28/2015             Extra Credit II
06/11/2015             End of Year Reflection
06/04/2015             Final Exams II
06/19/2016             End of Year Reflection II

*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!

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    Marjorie R. Heesemann is a chemistry teacher with 15 years of experience who is now working to develop resources for the Chemistry classroom.

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