Chemistry on a Budget: Organic Chemistry

I want to introduce some Organic Chemistry.  I’ll post resources in a separate article.  The first lab is  Density of Plastics.  Here is another Density of Plastics lab with a different strategy to identify the Big Six Plastics.  Here is a chart with their respective densities.  Look at the bottom of plastic containers for the number.  I need to collect several examples for this lab.  The lab materials also require calcium chloride, sodium chloride, rubbing or isopropyl alcohol, vegetable oil, glycerin, popsicle sticks, and egg cartons.  I am omitting glycerin because it’s too pricey.  This is an appropriate lab for kids ten and older to try.  Younger kids might need a lesson in Measuring Density by Displacement.  Now I need to see which plastics I already have on hand.

Chemistry on a Budget: Safe Chemistry Labs

What is keeping you from doing more labs?  I bet you have reservations about a lab’s safety.  I understand!   You may have questions about the chemical reactions taking place in a lab or the names of the chemicals used.  Try the ACS’s Middle School Chemistry lessons.  They are designed for middle school teachers who don’t have a background in Chemistry.  These lessons have videos, activities, and best of all detailed explanations for each activity and science concept.  The instructions have tips, sources for materials, and useful explanations.  For example, the lesson, Temperature Changes in Dissolving, has a demo with potassium chloride, sodium chloride, calcium chloride, sodium carbonate, and sodium bicarbonate.  The lesson has a note explaining what these chloride salts are.  Potassium chloride is a common salt substitute, usually available at the grocery store. Dishwasher detergent has sodium carbonate as the main ingredient.  It can be safely used in this demo.  If you are looking for more labs to enrich your chemistry program, start here.  Build your confidence!  You can do this!

Chemistry on a Budget: Burners

 And hot plates!  Here is an article about using sand baths for glass beakers on hot plates.  A post on social media suggested making a simple sand bath with sand in a mini-aluminum pie plate for beakers on top of a hot plate.  I use wire gauze under glass beakers on hot plate burners.

This post could be labeled Chemistry on a Shoestring!  We use several tools to heat chemicals.  We use electric burners to heat most solutions.  But when I heat chemicals in test tubes, we need a different source.  The Hydrate or Percent Composition lab works best with a Bunsen burner.  We used cans of sterno, instead.  We were running out of sterno; I broke out the two alcohol burners.  Here are detailed instructions to use a wickless alcohol burner.  Here are detailed instructions to use an alcohol burner with a wick.  My alcohol burners were in science kits I bought through Good Will.  Here is the most important piece of information!  The wickless burner uses denatured ethanol; the alcohol burner with a wick uses rubbing alcohol (isopropyl alcohol).  We dumped the alcohol down the drain after lab concluded—just to be safe.

I loathe alcohol burners.  I worry about fires endlessly.  Sterno usually works fine.  However, if you supervise the teens closely, these burners are fine.  If you have a gas stove at your home, use it to heat test tubes.  Be sure to turn on the hood fan. Do you have a camp stove?  This works well for heating test tubes, too.  

Chemistry on a Budget: Metal Reactivity Lab!

 My teens in the Chem Co-op are working on the reactivity of metals lab.  This is an inquiry lab based on Flinn’s Activity of Metals lab.  I used this lab and this lab as guides and background for the metal lab.  We used aluminum foil, mossy zinc, iron nails, steel wool, copper shot, copper II sulfate, zinc sulfate, magnesium sulfate, and a little silver nitrate.  Foiled Again! Uses copper II sulfate, copper II chloride, sodium chloride, and aluminum foil.  Use what you have on hand.  The goal is to see which metals are more reactive.  You can do this with drops in a reaction place, according to the directions in this lab.  I let the kids use plastic cups and make dilute solutions of the compounds, roughly 0.1 M solutions.  This is an opportunity to teach molarity.  I’m going to have the kids determine the concentrations of each solution, too.  Below are pix.

More mole pix!

 A student just sent me her mole pix.  She took pix with the chemicals on the scale.  Take a look!

Chemistry on a Budget: Hydrate Lab

Update: Here is a sample spreadsheet with the hydrate data.  The alcohol burners work better than sterno.

 The Chem Co-op class is in the middle of the Percent Composition or Hydrate Lab. We are right in the middle of the unit on moles.  The kids are learning how to calculate molar mass or formula mass.  The link above is a chapter from Prentice Hall Chemistry and explains hydrates.  The lab uses test tubes, hydrates, etc.  We use sterno to heat the hydrates in test tubes.  You could use an alcohol burner or heat the test tube over a gas stove.  Here is a link explaining how to heat compounds in a test tube.  Be sure to use only 2-5 grams of hydrate in Pyrex or Kymex, heat-tempered test tubes.  I did have the kids use an alcohol burner when we ran out of sterno to heat hydrates.  Please note we place sterno or burners on cutting boards because we use standard folding tables.

Chemistry on a Budget: Make a Conductivity Tester

 Here are detailed instructions from the Exploratorium to make a conductivity tester.  The materials are popsicle sticks, 9V battery, Christmas lights, masking tape, aluminum foil, all household materials.  Make solutions of magnesium sulfate (Epsom salts), sodium chloride ( table salt), isopropyl alcohol (rubbing alcohol), and sucrose (white sugar).  Use this lab as a guide.  Use more concentrated solutions.  If the conductor fails, it might mean the 9V battery is dead.  This type of lab eats batteries.

Chemistry on a Budget: Mole Labs

 The kids worked on mole labs today.  I used calcium chloride, Driveway Heat.  Sodium chloride, table salt works equally well.  I have some out for impromptu quizzes.  Below is the list of labs.  Only two kids have started the hydrate lab.  I’m assigning spreadsheets for the hydrate lab next week.  BTW I always have more lab activities than I think the kids can accomplish; today two teens did start the hydrate lab.  

Step One: Weigh one mole of baking soda, water, aluminum, and calcium chloride.  

#2. The kids each had a different mass to convert into moles of calcium chloride, aluminum, water, and baking soda.

#3. Treat pre-1982 pennies as copper.  Treat post-1982 pennies as zinc.  Determine the number of moles for both old and new pennies.  Each team had a different number of pennies. The kids weighed several Pennie’s and converted the mass to moles of either copper or zinc.

#4.  How many molecules of chalk are in your name?  I did not want pix of the teens’ names or for their calculations.  Most of the teens are still working through #3-#4.  The kids weigh a piece of sidewalk chalk before and after writing their name on cement.  Naturally, it was raining today.  So the kids wrote on the cement floor in the basement and wiped the floor after.  The kids must convert the difference in grams to moles, and finally into CaSO4 units.  CaSO4 is an ionic compound, not a molecule.

The teens also weighed different aluminum cans to determine the number of moles.  I’m saving cans, Pennie’s, aluminum, etc for quizzes.  I warned the teens, I’ll assign random substances to convert into moles as quizzes at any time.  These exercises may appear extraneous.  However, in my experience, the kids come away with a better grasp of moles.

Chemistry on a Budget: Moles!

 This week, the Chem Co-op class is learning Stoichiometry and moles.  Here is a slideshow overview for Stoichiometry.  Here is a well constructed mole lesson. Tomorrow, the kids are starting the lab series for moles: Weigh Moles, How many molecules of chalk are in your name?, and the Hydrate or Percent Composition lab.  

I pulled out baking soda, aluminum foil, water, pennies, chalk, and table salt.  First, ask the kids to determine what a mole of water weighs.  Then have them weigh a mole of water.  Recall the density of water is 1.0 g/mL; 18 grams equals 18 mL.  They can weigh water by zeroing a graduated cylinder or just pouring 18 mL of water.  Next ask them how many moles are in a piece of chalk, or ten pennies, or 25 mL of water.  Finally, the kids are going to write their names in chalk to determine the number of chalk molecules in their names. 

I’m using sidewalk chalk, which is mainly made of gypsum, mainly calcium sulfate dihydrate.  If you have plaster of Paris and paint, make your own chalk.  

You can use pennies teach moles, too.  Pennies minted after 1982 are mainly zinc; Pennie’s minted before 1982 are mainly copper.  Here is the link with the percent composition of older and newer pennies.  Initially, I treat post-1982 pennies as zinc and pre-1982 pennies as copper.  You could use them for a lesson in percent composition, too.  Round up your Pennie’s, chalk, and household materials and teach moles!

Chemistry on a Budget: Color Change!

Color Change is a great chemistry topic.   Start here with ‘Chemistry Colors Our World’.  Scroll down for the color change activity using blueberries and the chromatography lesson with black, water-soluble markers.  This series of brief articles are part of the resources for National Chemistry Week.  (Here is the 2022 set of resources.)  Have you tried color changing milk?  This is easy and cool.  You just need milk, food dyes, and a drop or two of dish detergent.  Science Bob has this Rapid Color Changing Chemistry experiment which requires a few more household chemicals: vitamin C tablets, household starch, hydrogen peroxide, and iodine. You can substitute cornstarch or potato starch for the household starch. This is an Iodine Clock experiment.  

Acid-base chemistry has loads of color change labs: pH and Color Change (requires universal indicator), Red Cabbage Lab, Valentine Science (requires phenolphthalein), and two ways to make Rainbow Wands.  See?  You can do loads of fun labs with simple materials.  Let’s stick to a budget!

Chemistry on a Budget: Salt!

 If there are loads of labs with sugar, are there labs with salt?  Yes, there are!  Let’s start with a bit of background, Shaking Out the Facts about Salt!  This is another Chemmatters magazine article for teens.  First, grow salt crystals with table salt and Epsom salts.  If you can find alum, it makes excellent crystals.  Here is a wiki how with detailed instructions.  Try both iodized and natural salts.  

Try this lab, Solubility of a Salt.  Teens will have another opportunity to graph, either by hand or with a spreadsheet.  Here are several Salt experiments to try.  One more topic: Salting Roads! This is another Chemmatters article to give teens a bit of background about freezing point depression.  Winter is the right time to Melt Ice with Salt!  Use any salt you have on hand: Epsom salt, Kosher salt, table salt, Driveway Heat, (calcium chloride), etc.  Bag a lot of ice cubes.  Use the same masses of ice and salt for each trial.  Which salt works best to melt ice?  I didn’t locate as many salt ideas as sugar.  Salt is another cheap, household substance to use for another round of substantive labs.