Summer is ending and it's time to think about how to start off your class year. I recommend setting class rules at the beginning of the first day, but that won't take an entire class!
One lab that is interesting, colorful, has temperature changes and gas production is "Flash in a Bag" (sometimes called "Chemical Reaction in a Bag".
Students must wear goggles when performing this -- be prepared to talk about this lab's safety.
Here's a simple demonstration of the reaction -- I made this a discovery experience, and could refer to it many times.
I performed this lab with one bag (similar to the video) and actually twisted the bag between the solid and liquid reactants -- then the zip-loc bag could be sealed before the ingredients were mixed.
I allowed the students to handle the bag during the reaction -- the temperature changes could be felt and the gas production was exciting!
One lab that is interesting, colorful, has temperature changes and gas production is "Flash in a Bag" (sometimes called "Chemical Reaction in a Bag".
Students must wear goggles when performing this -- be prepared to talk about this lab's safety.
Here's a simple demonstration of the reaction -- I made this a discovery experience, and could refer to it many times.
I performed this lab with one bag (similar to the video) and actually twisted the bag between the solid and liquid reactants -- then the zip-loc bag could be sealed before the ingredients were mixed.
I allowed the students to handle the bag during the reaction -- the temperature changes could be felt and the gas production was exciting!
Again, goggles are to be worn, and students must to wash their hands, with soap, before removing their goggles.
From this experience, you later can have a brief lecture about the signs of chemical change (color change, production of a gas, temperature change) as well as the concept of exothermic and endothermic change.
If desired, the chemical reaction can be written, using it to introduce the chemical language, with phases noted, and even balancing to show a final result.
Here is a lab page that is a brief set of lab instructions:
http://www.chymist.com/Chem%20in%20ZipLock%20bag.pdf
The indicator doesn't have to be measured, one or two pipets of indicator is sufficient.
An explanation of the chemical changes observed was found at:
http://www.elmhurst.edu/~chm/demos/reactioninbag2.htm
A slightly edited version is below:
Explanation: A chemical reaction occurs between the calcium chloride and the baking soda in which a double replacement reaction takes place. The two solids switch partners and form a new substance--the precipitate calcium carbonate.
Calcium chloride + baking soda (sodium bicarbonate) --- calcium carbonate + sodium chloride + hydrogen ions
CaCl2 + 2 NaHCO3 ---> CaCO3 + 2 NaCl + H+ ions
As the reaction proceeds, the bicarbonate breaks down first to make hydrogen ions, an acid. This acid then converts some of the bicarbonate to carbon dioxide gas which begins to blow up the plastic bag.
Hydrogen ions + sodium bicarbonate ---> carbon dioxide + water + sodium ions
H+ ions + NaHCO3 ---> CO2 + H2O + Na+
A good summary of the reactions (on Page 3) is at:
https://www.flinnsci.com/media/621024/91419.pdf
This lab is an exciting beginning to the course for students and an simple preparation for the teacher.
Check out my lab book "Chemistry on a Budget" available at amazon.com and lulu.com -- it contains 13 labs that require consumable materials you can purchase at local stores -- and it's only $20!
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
Each lab is presented with two possible report formats -- both labs use the same procedure but each has a different conclusion -- one with 10 questions to be answered as a conclusion, the other with a full laboratory report required. This gives the teacher the option of what type of report is desired, and each version is designed to be just two pages. This way the teacher can photocopy just one 2-sided page per student (saves paper).
It will take a little time to get to you, so order it and enjoy the rest of your summer vacation!
Have a good week!
From this experience, you later can have a brief lecture about the signs of chemical change (color change, production of a gas, temperature change) as well as the concept of exothermic and endothermic change.
If desired, the chemical reaction can be written, using it to introduce the chemical language, with phases noted, and even balancing to show a final result.
Here is a lab page that is a brief set of lab instructions:
http://www.chymist.com/Chem%20in%20ZipLock%20bag.pdf
The indicator doesn't have to be measured, one or two pipets of indicator is sufficient.
An explanation of the chemical changes observed was found at:
http://www.elmhurst.edu/~chm/demos/reactioninbag2.htm
A slightly edited version is below:
Explanation: A chemical reaction occurs between the calcium chloride and the baking soda in which a double replacement reaction takes place. The two solids switch partners and form a new substance--the precipitate calcium carbonate.
Calcium chloride + baking soda (sodium bicarbonate) --- calcium carbonate + sodium chloride + hydrogen ions
CaCl2 + 2 NaHCO3 ---> CaCO3 + 2 NaCl + H+ ions
As the reaction proceeds, the bicarbonate breaks down first to make hydrogen ions, an acid. This acid then converts some of the bicarbonate to carbon dioxide gas which begins to blow up the plastic bag.
Hydrogen ions + sodium bicarbonate ---> carbon dioxide + water + sodium ions
H+ ions + NaHCO3 ---> CO2 + H2O + Na+
A good summary of the reactions (on Page 3) is at:
https://www.flinnsci.com/media/621024/91419.pdf
This lab is an exciting beginning to the course for students and an simple preparation for the teacher.
Check out my lab book "Chemistry on a Budget" available at amazon.com and lulu.com -- it contains 13 labs that require consumable materials you can purchase at local stores -- and it's only $20!
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
Each lab is presented with two possible report formats -- both labs use the same procedure but each has a different conclusion -- one with 10 questions to be answered as a conclusion, the other with a full laboratory report required. This gives the teacher the option of what type of report is desired, and each version is designed to be just two pages. This way the teacher can photocopy just one 2-sided page per student (saves paper).
It will take a little time to get to you, so order it and enjoy the rest of your summer vacation!
Have a good week!
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