Tag Archives: Apologia Chemistry

The Conservation of Mass

Looks like I need to back track a little, since I apparently have skipped a few lessons.

Module 3 of Exploring Creation with Chemistry – The Conservation of Mass

Uh?

All that means is matter cannot be created or destroyed; it can only change forms.

In a nut shell, when matter goes through a wiz-bang change the total mass remains the same. Ta-dah!  Still don’t get it?  Ok.

Get a pair of funky colored goggles and neon yellow rubber gloves.  Must haves for all chemistry labs.   Seriously.

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Obtain items for exp. 3.1: beakers, watch glass, Lye (we used Drano – washes your troubles down the drain), vinegar, water, pot, purple cabbage, stove, mass scale, stirring rod, etc..  In this experiment we boiled cabbage to get the color out and into the water.  Now we are trying to figure out if the mass of matter is the same before and after it goes through any kind of change.  To do that, we have to measure everything.

We measure the beaker, the lye, the watch glass, the everything…  Here you see my pink student measuring her beaker in her mass scale.  Sorry, I don’t have any measurements to give, because I no longer have their lab write-ups and can’t remember what the weights were.

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While the cabbage is boiling  you stop, put your finger on your nose and think about the experiment and where it is going.

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Measure out a specific amount of the Lye and place it on the watch glass.   Then have this conversation with one of your students?

  • Student: Mrs. Goodrich, what happens if you get Lye on your fingers?
  • Me:  It burns your skin.
  • Student:  Can I touch it?
  • Me:  No.
  • Student:  Uh, I think I got some on my hands because they are burning a little bit.  Can I go wash my hands?
  • Me:  Sure.  I also got some on my hands.

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Here some of the cabbage water is in the beaker with some vinegar.  You can see just a little bit of pink at the bottom of the beaker in the mass scale.  Vinegar (acid) turns the anthocyanins pink.

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Next step is to tip the watch glass and pour the Lye into the pink liquid.  Lye is a base and neutralizes the vinegar and turns it into a lovely shade of yellow snot.  I hate the word snot, but that is what the students called it.

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So, we had vinegar, Lye, and water with cabbage coloring in it.  All was measured. Let’s say it measured XX grams.  It was then mixed all together causing chemical changes to occur and the whole thing was measured again.  The mass was XX grams.  Ta-dah!

Matter cannot be created or destroyed; it can only change forms.

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Ionic or Covalent?

Apologia Chemistry

We are making our way through Module 3 of Exploring Creation Through Chemistry.    In this module we learned there must be at least one metal atom and at least one nonmetal atom for a compound to be classified at Ionic.   The compound will be Covalent if it contains only nonmetals.

Experiment 3.2  will show us that Covalent compounds do not conduct electricity, but Ionic compounds will.

Students attached copper wires, using electrical tape,  to a 9V battery.

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The other end of the wires were put into a beaker that had distilled water.  Distilled water is 99% pure.  The students kept their eyes on the beaker…. for a while.  Suddenly they are getting bored.  Why?  Because absolutely nothing is going on!  What is the purpose of this experiment if nothing is going on?  Good question, but there is something going on and that something is nothing.    That means distilled water is a covalent compound made up of Hydrogen and Oxygen.

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Next we add in some Sodium Bicarbonate, aka Baking Soda.  It has at least one metal in there.   NaHCO3  Do you see it?

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Now oooo and ahhhhh.  Something is happening here.  See those bubbles?  That means electricity is being conducted and it is breaking down the water.

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Next experiment….contacting alien beings.  Or other Chemistry students.  Same thing.

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I Built a Calorimeter and Determined the Specific Heat of a Metal

That title sounds like I am awesome smart doesn’t it?

In reality, I just stuck two Styrofoam cups together and plugged numbers into an equation.  Do I still sound awesome smart?  Didn’t think so.

We just finished Module 2 of Exploring Creation with Chemistry by Jay Wile. For Experiment 2.2 a calorimeter is needed to perform the experiment.  Styrofoam cups are a great insulators, so they work well as a calorimeter.

A calorimeter is a device used to measure quantities of absorbed or released heat or for determining specific heats.

Lab 2.2 requires two styrofoam cups, but does not state there should be a top on the cups. I kept thinking a lot of heat will be lost out the top.  So, I took a look in the All Lab, No Lecture book and it gives instructions on how to make a lid for the cups.

You need two circles for each calorimeter.  I made one for each student to save time in the classroom.  I bought two thick foam sheets from Michale’s and cut one 3 1/8″ diameter and the other 2 3/4″ diameter.

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Elemer’s Glue was used to glue the first two together, which didn’t work very well.  A hot glue gun works a lot better.   Glue the smaller circle to the larger one.

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Drill a hole through the center of both lids.  The hole needs to be big enough for the thermometer to slip through.

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The smaller side sits down into the cup, while the larger side sits on top of the cup.  This helps trap in the heat to get a more accurate measurement.

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Now to figure the specific heat of a metal:

A large piece of metal measuring at least 30 grams is needed.  Two heavy nuts were used to get the amount of mass I needed for the experiment.  Measurements are below.

We need the metal heated to 100 ºC, boiling point. Once the metal was heated to 100 ºC, they were quickly removed and placed in the calorimeter, and lid closed.

The thermometer was gently swirled to get the heat distributed evenly.

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Record keeping is essential in Chemistry. Always record all numbers.

  • Mass of the metal. 37grams
  • The calorimeter  was weighted to get the mass.  9grams
  • Water was added to the calorimeter and measured again.  124grams
  • The difference is the mass of the water.  115grams
  • Initial temperature of the water.  26 °C
  • Final temperature of the water.  28 °C
  • Initial temperature of metal.  100 °C

Now we can calculate the specific heat of the metal, using the following equations (these are explained in Exploring Creation With Chemistry :

  • q = m •  c •  ΔT
  • -q object = q water + q calorimeter

And here is a photo of my work.

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The specific heat of the two nuts was .36 J/g°C

Each of my students had similar results.

Please do not ask me to explain my calculations.  I cannot do that over the internet.  🙂

Chemistry

Calibrating a Thermometer

Apologia Chemistry  – What’s happening at my co-op.

Did you know that most thermometers are not accurate?  I had no idea.

In Module 2 we learned the boiling point of water measured in Fahrenheit is 212 degrees.  In Celsius it is 100 degrees.  The freezing point of water measured in Fahrenheit is 32 degrees, while in Celsius it is zero degrees.

This may not be a surprise to any of you and it certainly isn’t a surprise to me.  However; I have always had to ask someone what is the boiling point of water in Fahrenheit or Celsius, because I forget…until now.  It clicked.  I remember it.  I’m like Dorie in Finding Nemo.

Fahrenheit 212 boiling.  Fahrenheit 32 freezing.
Celsius 100 boiling.  Celsius 0 freezing.
Hey, I remembered.  Want me to say it again?  Ok…..

Please tell me that is something to be proud of.

Back to class!

Each student is given a thermometer (Celsius) they will be working with throughout the year.  To accurately calibrate the thermometers we have to find where the measurement stops at freezing.

We used crushed ice and cold water.  After a set amount of time, they take the temp.  If it is below zero, they are to add whatever to get to zero.  If it was above zero they are to subtract whatever to get to zero.  Any time the students use their thermometer they have to make adjustments on every measurement.

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You know, I don’t think the kids can get more excited.

Once the thermometer is calibrated, we set the beaker on a hot burner to start warming up the water.  They were to take the temp. every minute and hopefully get to boiling.

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Four students heated their waters, while one recorded their mesurement.  Since I could do this experiment at home, my daughter was the one to do the recording.

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Keep on stirring.  We never made it to boiling.  Hot plates and alcohol burners are not chemistry experiment friendly.  ug…..

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The students made a graph of the temperature to time.  What it should show, and it does here, is that the freezing point remains the same for a short time and then rises.  What it should also show, but doesn’t because we couldn’t get it to boil, is once it hits boiling at 100 C, the temp remains the same as long as it is a rolling boil.

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Once home, the daughter and I performed the same experiment.  We put the beaker right on the burner.  Oh, you noticed I have a beaker in my home.  Are you asking if I have Chemistry equipment in my home?  Why yes.  Yes, I do. I’ll post about all the Chemistry goodies I have later.

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When it is at a rolling boil, can’t be stirred down, the temp should read 100 degrees C.   My daughter’s thermometer calibrated at -1.  That means she has to add 1 to all of her measurements with this thermometer.

As you can see here, the temp stopped at 99 degrees.  Adding 1 makes it 100, where it should be.

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That, people, is calibrating a thermometer. 🙂