Apologia Chemistry: Acids and Bases

Update: Household pH lab

Update:Acid Base Pix on Imgur

I’ve tried reloading pix, saving them differently, etc.  I think the temporary solution is going to be a link from Imgur.

The class is still working on acids and bases.  Still.  The kids are making series dilutions with 1M HCl and 1M NaOH  They are using these dilutions to test different indicator solutions using the diluted HCl and NaOH: universal indicator, Sudan IV, phenol red, phenolphthalein, bromothymol blue, cabbage powder, and pH strips.  The kids are becoming adept at making series or serial dilutions.  My goal is to hammer home the definition of pH and its relationship to concentration of diluted acids and bases.  I emphasize the fact that the pH scale is composed of relatively weak solutions of acids and bases, less than 1M concentration.  We also introduced probeware.

Apologia Chemistry: Acid Base Titration Lab

The next few classes are labs, beginning with this microscale, acid-base titration lab.  On Tuesday, we had mixed solutions and then make a series or serial dilution with one of the solutions.  (Unfortunately, I couldn't find my copper sulfate in the basement.  Yes, I ordered more on Amazon.  I'm sure I'll find it right after the order arrives.)  I wanted to use the copper sulfate because the gradations of blue are a good visual for dilutions.  Nonetheless, the kids know how to make a simple dilution.  Today, we followed microscale lab precisely.  (Will wonders ever cease?)  The only tiny modification is that I prepared 1M solutions of HCl and NaOH.  The kids had to dilute these to 0.1 M concentrations themselves before doing the titration.  I ordered the concentrated HCl and NaOH from Home Science Tools to make the solution of HCl.  The NaOH was easier.  I ground up 4 g of NaOH with a total of 100 mL to make 1M solutions.   The kids had to dilute 1M NaOH and 1M HCl to 0.1M HCl and 0.1M HCl before beginning the lab.  One pair of girls did a test with the two 1 M solutions to assure they were both 1M concentration.  The problem is that the HCl states on the bottle it's between 32 and 36%.  My bottle had been on the shelf awhile and may have lost a little water from solution.  I assumed it was 11.65M.  I was much more confident of the NaOH solution because I ground and mixed it myself.   Now, I'm positive you're planning to skip this lab.  Hold on!  This lab kit is pricey--but has directions.  Below are a few photos.

Apologia Chemistry: Molarity or Concentrations

Today the class is making solutions with four solutes and water as a solvent.  The chemicals on hand were zinc sulfate, magnesium sulfate (Epsom salts), potassium chloride, and calcium chloride (driveway salt).  Molarity (M) is a measure of concentration.  A 1 M solution has one mole of solute dissolved in one liter of water.  I did not want vats of solutions; the kids made 50 mL solutions of 1M concentrations.  The thing to remember is to add 25 mL of water first, then the solute (such as calcium chloride), and finally enough water to make a total of 50 mL of solution.  If the kids measure 50 mL of water and then add the solute, the concentration is more dilute than 1 M.  This lab may seem obvious.  Long experience indicates that kids understand the material much better after making four or five solutions.  This is similar to the mole lab in which the kids weighed one mole of a half of dozen metals and chemicals.

Apologia Chemistry: Acids and Bases

We are back from Easter Break. Today we started our study of Acids and Bases with an introductory lab: Household Chemical Tests. (Our lab is similar to this one.) I brought lemon juice, breakfast drink mix, calcium carbonate, baking soda, vinegar, table salt, mouthwash, Windex, detergent, sodium hydroxide, citric acid, basically assorted household chemicals on hand.  I ordered litmus and pH strips and brought Sudan, Phenol Red, and Universal Indicator solution as test reagents.  The kids proceed to test each household chemical, such as vinegar with all of the test strips and indicator solutions.  The dry ingredients must be diluted with water before testing.  The goal is for the kids to design a lab while becoming familiar with common acids and bases.  Done.

Apologia Chemistry Flame Tests, Quantum Theory, and the Periodic Table

Quick Update:  Read Dr. Wile’s Module on Atomic Structure.

Last week, we met Tuesday and completed the flame tests lab, which involves a spectroscope and calculations.  (Thursday was a snow day--no class.)  Before the lab, I had introduced Quantum Theory to the kids and explained how the Periodic Table coincides with electron configuration charts.  Now they have seen and used a spectroscope, observed the unique colors of the flames for different compounds, it's time to tie these seemingly disparate ideas together.  Wish me luck.

Apologia Chemistry: Flame Tests

Flame Tests are fun.  Let me share one quick idea: Flame test Crayons on Etsy!This lab is usually a favorite.  Yes, I do use Flinn's Flame Test kit.  Home Science Tools has an excellent Spectroscope Analysis Kit to order.  The reason I like this kit is the the spectroscope is included along with instructions.  Flinn's lab is written to include a spectroscope.  Here's how the lab goes.  First, I show the kids what a spectroscope is and how to use a fluorescent light bulb to calibrate it.  The spectroscopes are hard to use.  Theses flame test candles (also available through Amazon) produce a steady flame color which is easier to use with a spectroscope.  Here are the chemicals used in the flame test candles.)  The main issue is the flame. The lab is designed for use with a Bunsen burner to produce flame tests similar to these.

First, the kids practice using the spectroscopes with a tube fluorescent bulb in order to read the nanometers.  Then the kids experiment burning these chemicals: strontium chloride, potassium chloride, calcium chloride, lithium chloride, and copper chloride.  We used tea candles.  The kids tried dipping the wood splints (coffee stirrers) into the chemical samples.  I find the scoopulas filled with the chemical work better.

Once the kids determine the flame color for each chemical, they can use the chart in the Flinn lab for the wavelengths if they're unsuccessful determining the spectra.  Here's the key.  Read the directions and teacher tips from the Flinn lab carefully.  I usually have the kids use the energy formula to calculate the change in energy. (This requires a scientific calculator to handle the exponents.)  But, when I taught kids with special needs, we just created a chart with the chemical formula, its name, and flame color without doing these calculations.

Apologia Chemistry: Quantum

Last time, we created periodic charts with Flinn's Periodic Chart Lab and began exploring Quantum Theory.  Today, I spent time explaining more about Quantum Theory and showed the kids how to write Electron configurations.  These rules, this tutorial, this video, and this dynamic periodic table will help.  My emphasis is on the relationships among line spectra, the Periodic table, and the elements' electron configurations. This is one activity that probably requires Khan Academy.

Apologia Chemistry: Periodic Properties Lab

We are still working on periodic properties.  Today, I brought Periodic Chart Lab from Flinn.  The idea is to recreate a periodic table based on each element's properties, such as boiling point, much as Mendeleev did.  The kit cost about $15; Flinn will deliver to a church office--but not a house.  In this activity, the kids use arrange the cards into three rows and columns according to their properties.  Flinn's directions are always excellent and include teacher notes with an answer key. Flinn's "It's in the Cards" is also terrific--but more expensive. Try it.

  

Apologia Chemistry: Models, Trends, Definitions, and March Madness

Let me share Flinn’s March Madness just for fun.  And it’s March!  The kids are at different places completing their models and timelines.  I keep activities on hand just for these occasions.  Flinn has similar activities, such as Sweet 16 Chemistry Compound Tournament.  I had the kids summarize all of the trends they modeled: atomic radius, Ionic radius, Electronegativity, electron affinity, boiling point, melting point, density, valency, metallic character, nonmetallic character, and first ionization energy.  BTW, I let the kids model each trend creatively and supply markers, paper plates, straws, etc.      After completing their models, the kids put the summaries on the board for everyone to copy.  Here are a few examples.

Apologia Chemistry: Periodicity or Periodic Trends

We are mopping up general chemistry lessons, one of which is Periodic Trends (Module 8 Molecular Structure): metallic character, nonmetallic character, ionic radius, atomic radius, electron affinity, electronegativity, first ionization energy, density, boiling point, melting point, and valency.  I wrote these and assigned each kid a different one.  The kids may use a variety of materials to represent their assigned trend: toothpicks, straws, color, etc.  They must define the trend and explain the pattern across the main group elements of the periodic table. 

Apologia Chemistry: Atomic Theory Timeline

Time lines
In the Module, Atoms and Molecules (Module 3 in 1st edition) has a section on the development of atomic theory.  I think everyone should learn how to make Time lines.  Here are instructions.  I gave the kids this list of scientists who made contribution to Atomic Theory: My list has Amedeo Avogadro, Neils Bohr, Louis de Broglie, James Chadwick, John Dalton, Werner Heisenberg, Dimitri Mendeleev, Robert Millikan, Hantaro Nagaoka, Ernest Rutherford, Erwin Schrodinger, and JJ Thomson.  The kids have to research their births, deaths, and each individual's contributions' to atomic theory.  (Take a look at the link for time lines at the top.  There is a good copy of a student's timeline.)  I think making a timeline and researching the information is the way to understand the scope of the development of the atomic theory.  You may want to include a discussion about the Greek philosophers Leucippus and Democritus.  After writing the list of scientists, I explain the origin of 'atomos'  and explain their contributions.  We omit the Greeks because it would distort the time line.