Chemistry Lab: Composition of a Hydrate

This is one of my favorite chemistry labs and here's why: It has a simple materials list. It is easy to set up and break down. It yields great results. It provides a quality lab during your unit on chemical formulas, a unit in which labs are hard to come by. It has a mathematical component which students need. Students calculate percent error. Students learn how to write the formula of a hydrate. Students compare experimental data to theoretical data, which is so important!

That's a lot of reasons why you should do this lab! 

Here is the link in my TPT store:  Composition of Hydrates Lab

It's best to use this lab when teaching your unit on how to write chemical formulas and how to name chemical compounds. Hydrates are compounds that have some number of water molecules attached to them. The premise of the lab is simple: A known mass of a hydrate is heated to release the water of hydration. The mass of the resulting anhydrous salt is determined. The difference in the mass of the hydrate and the mass of the anhydrous salt can be used to determine the formula of the compound.

In our lab, we used copper (II) sulfate pentahydrate. A fine crystal is needed for the lab. Since we only had the medium crystal in stock, my students used a mortar and pestle to grind the crystals into a finer powder.

The hydrate is heated over a Bunsen burner in an evaporating dish to remove the water of hydration. But first the empty evaporating dish must be heated to remove all water, allowed to cool briefly, and the mass of the empty dish determined. 

The difference in the "before mass" and the "after mass" is used to determine the mass of water lost. Students are given directions in how to use this information to determine that the compound used was copper (II) sulfate pentahydrate. 

I love the simplicity of this lab and the fact that my students clearly understood how to use this data to determine the formula of the compound. All in all, it's a great day in the lab!

How much Vitamin C is in your fruit juice?

Lab: Determining the Amount of Vitamin C in Fruit Juices

I  have been doing this lab every year for a long, long time.  I always enjoy it, and so do my students. I often do this lab with my biology students when teaching about nutrition and digestion, but my favorite use of this lab is with my chemistry classes.  This lab is perfect to introduce the idea of titrations, equivalents, and as a review of dimensional analysis.

In this experiment the student will use a lab procedure known as a titration to determine the amount of Vitamin C found in a 6 ounce serving of various fruit juices.  I most often use orange juice, pineapple juice, and apple juice. 

A titration is the controlled addition and measurement of the amount of a solution of known concentration required to react completely with a measured amount of a solution of unknown concentration.  Titration provides a means of determining the chemically equivalent amounts of two substances.  

The materials list is short and consists of items found in almost all labs..... no fancy equipment required!  You will need:  Spot plate, Thin stemmed or microtip Beral pipets  (or medicine droppers),  White paper for background, Ascorbic acid standard solution,  Apple juice,  Orange juice,  Pineapple juice, Starch solution,  Iodine solution and Plastic Toothpick (stirrer).

In order to determine the amount of Vitamin C in the fruit juice, the student must first do a titration using a vitamin C (ascorbic acid) solution of known concentration.  An iodine/starch complex is used so that a color change can be detected.  The number of drops of iodine added will be used to determine the amount of Vitamin C present in the juice.  

When ascorbic acid (Vitamin C) comes into contact with iodine, it is oxidized to form dehydroascorbic acid.  When Vitamin C and iodine are in solution together, they will form iodide.  As iodine is added during the titration, iodide will continue to be formed until there is no more Vitamin C left in the solution.  At this point, iodine becomes present in the solution and the starch turns a blue-black color.  The starch is used as an indicator because it turns black in the presence of iodine, but not for iodide.  The amount of iodine that is added during the titration can be used to indicate the amount of Vitamin C present in the fruit juice.

Set up for the lab is quick and easy, and does not take a lot of advance preparation.  

This lab is available in my TpT store and can be viewed here:  Determining the Amount of Vitamin C in Fruit Juices.

Yellow Starthistle Tops the Plant "Most-Wanted" List

At first glance, the Yellow Starthistle looks like a beautiful wildflower.... one that you would be delighted to view during a nature hike.  However, this plant has quickly risen to the top of the "plant most want listed" as an invasive species in the United States. As you know, an invasive species is one that is introduced into an area or habitat to which it is not native.  In this new area, the checks and controls that keep a species from overpopulating are not present.  As a result, the species increases so rapidly that the local (and native!) species are often driven to extinction.

The Yellow Starthistle ( Centaurea solstitialis) is native to Eurasia. It grows as part of balanced ecosystems there because it is kept in check by a variety of local herbivores, as well as other plant species that have co-evolved with it in its native habitat. It is thought that the Yellow Starthistle was introduced into California in the 1850's during the California Gold Rush when imported alfalfa seed arrived that was contaminated with the seed from the Yellow Starthistle.  Once introduced into the United States, it quickly took hold, and has been problematic ever since.

Here is the quick-list of facts about this highly invasive species:

• A single staked plant may produce a root system that extends to an area of three feet outward from the stalk.  It rapidly depletes moisture in the soil and out-competes the local and native species in its ability to obtain water.

• It has become very common along roadsides, pasture lands, and wildlands.  
• It is poisonous to horses and causes a disease called "chewing disease."  This can be fatal to the horse if treatment is not received.  Horses are the only animals known to be affected.
• The plant may grow to a height of 5 feet.
• Seed output may be as high as 30,000 seeds per square meter.  
• Invasion of the species is increased by cars along roadsides and by livestock.  Livestock that is suspected of ingesting the Yellow Starthistle should not be shipped to uncontaminated areas.

Yellow Starthistle seedling

What are methods of controlling this invasive species?  In 2003, 4 insect species were introduced from Europe as a means of control.  These agents of biological control included 2 weevils and 2 flies. Each of these insects lays its eggs on the flower/seed head of the plant and, as a result, reduce the number of seeds that the plant produces. All four insects are host-specific to the starthistle and do not attack native species.  Grazing animals such as sheep, goats and cattle are also an effective means of control.  A variety of chemical agents are also used.

In an interesting, but sad turn of events, the Yellow Starthistle has invaded and is quickly taking over the Sierra Nevada habitats in Yosemite National Park.  You can read all about Yosemite's attempts to control this plant at this link.

Ringing in the New Year With A Brand New Look!!

Hello everyone!  And Happy New Year!!  I hope everyone had a wonderful holiday season.  Teachers and students are back to school and hard at work.  I have a new energy and excitement for both my teaching and my blogging!  I am always excited about teaching, and l am looking forward to trying some new things with my classes this semester.

Why am I so excited about blogging?  Well ........ What do you think of my new blog design?

Let me start off by first thanking the incredible person who put together this custom design for me.  Michelle Tsivgadellis, also known as "The 3AM Teacher" is completely and totally responsible for the amazing new look.

Michelle was delightful to work with, and she completely understood the "type" of look I wanted for my blog. She is kind and patient and efficient, and I recommend her whole-heartedly!!

Now that the design work is done, the onus is upon me to start cranking out some new blog articles.  Let's see... I teach full time, have a family to take care of, grade papers to all hours of the night...  Sigh ... I'll try to fit blogging somewhere in there!

Wishing you good luck in your teaching this semester!

Genetics Complete Unit Plan Bundle

Everything you need (and more!) to teach this unit!

It is no surprise to anyone who knows me that Gregor Mendel is my favorite scientist and I love teaching genetics to my biology students.  Who wouldn't? Students love learning about genetics, which makes teaching genetics wonderful.   

Interested Students + Lots of Awesome Questions = FUN TEACHING!

This was one of the first unit plan bundles that I posted in my TeachersPayTeachers.com store. It contains everything you need to teach this unit to a biology class... A PowerPoint, notes for teacher and student, 3 labs, 7 practice problem worksheets, 5 quizzes, a review game, a crossword, and a unit test. I have learned a lot since those early days, and the facelift on this bundle has just been completed. Graphics have been improved, a few typos have been corrected, and more complete answer keys have been added. This bundle has received such great feedback, and I am most appreciative to all who have purchased it. Be sure to go back to TpT and download the new version. It is a free download to those who have previously purchased it. 

Feedback:  "This has great resources and it is amazingly interactive."

Feedback:  "It's always great to get new ideas and problems for students to do."

Feedback:  "This lesson plan bundle deserves an A+........so helpful when teaching students about gentics!!"

Feedback:  "This material was excellent. It saved me time and covered everything I needed to cover for my mid term exam."

Feedback:  "Very organized and sequential. A great resource."

"I cannot tell you enough that your Complete Units are Wonderful!! I am in my first full year of teaching and it has given me ample opportunity to focus on my students abilities rather than being stressed. Thank you so much!"

Click here to view my Genetics Complete Unit Plan Bundle.

Recycling in the Science Lab!

Let's do our part to save the Earth!

I tend to get on my "Save the Planet" soapbox a lot.   No matter what the biology or chemistry topic I am currently teaching, I try to find a way to remind my students that we live on a fragile planet and that it is our responsibility to take care of it.

This school year, I reminded myself that actions speak louder than words, and I made a concerted effort to use recyclable items in my science lab.  I started by bringing a few items from home and using them for various purposes.  My students started to notice, and they began to bring in items as well.


Here are just a few examples of how we are using recyclable materials:

How many ways can you use the Styrofoam meat trays that you get from the grocery store? The tray seen above is the 2-lb hamburger meat tray!   I have a recycle bin at my house, and I am an avid recycler.  Finally, it occurred to me that these trays have many uses in my lab.  When I am setting up a lab, I line up 15 of these trays.  I add the lab supplies needed to each tray.  Students simply pick up the entire tray and carry it to their lab station.  I especially love to use these trays when stains are needed in the biology lab.  It keeps my lab tables clean and the stain washes right off the Styrofoam.

Our school had a HUGE stack of these paper book covers.  They are actually a slick, magazine type of paper.  These were about to be thrown away when I grabbed up 100's of them and hauled them to my lab.  I use them like place mats.  Students do their lab work on top of the paper mat.  It keeps my lab tables clean and minimizes the amount of clean up at the end of the class period.  When they are dirty to the point of no longer being usable, they go into the recycle bin.

This container came home from the grocery store full of strawberries.  It is the perfect size to hold all of my lab scissors.

The blueberry container is a bit smaller than the strawberry container.  It is perfect for smaller items such as these C-clamps.

I am very proud and excited to report that these small efforts have really increased awareness about recycling amongst my students.  Students are brining me items from their homes with ideas of how we might use them in our lab.  

This is a bit of a double-edged sword, though.  Kids are bringing me a lot of trash, and there are only so many uses for their recyclable items.  So when I received too much stuff, or when I cannot find a use for an item, we can always resort to this!  

I am super excited that every single room in our school has one of these!!

Here are a few links to sites that have awesome ideas about recycling in the school environment:

School Recycling

Using Recycled Items for School Projects

Recycling at School

If you have other ideas, I would love to hear them!

Dichotomous Classification Keys: Science Students Love Them!

Dichotomous classification keys are often used in field guides to help the user quickly and easily identify trees, flowers, insects, frogs, etc.  They are also a very effective teaching tool in our science classrooms.  They can be used to teach scientific terms and characteristics of any type of living organism.  But I think one of the most important uses in our classroom is the fact that they reinforce observation skills, and strengthen problem solving and critical thinking in our students.

I receive many requests for classification keys on different topics.  Over the years, I have developed quite a few activities that use the dichotomous classification key.  

My newest is called "Dichotomous Key to the Genus Smiley."  In this simple key, students first learn how to use a dichotomous key.  But the best part of this activity is that students are also required to develop their own dichotomous key to key out 6 different insects.  This requires a higher level of thinking and problem solving that provides excellent practice of these skills for our students.

Dichotomous Key to the Genus "Smiley"

Additional products that use the dichotomous classification key are:

Dichotomous Key to a CRAZY Animal Kindgom

Freebie!  This is one of my favorites: Dichotomous Key to Holiday Giving and Community Service

Let's Build a Cladogram!

Let's Learn to Use and Build a Dichotomous Key!

Lab: Use of Dichotomous Key in Classification

Click here to view all of my classification/taxonomy products.