Blog Archives

Blog Topic List

9/25/2014

I am posting this page a day early because I realized that my readers might appreciate / benefit right now.

I have added a Topic List of the entries in this Blog so you can find the dates of previously discussed material. This should make your search for the information you need a little easier.

I hope that now you are discussing Chemistry Laboratory Safety and getting Laboratory Safety Contracts signed. I posted about this topic on July 13, 2014. If you haven't ready it already, check it out!

*You are approaching the mid-point of the quarter -- try to get one test and one lab in so you have a realistic grade estimate to report.

Remember that my lab book "Chemistry on a Budget" is available for $20 at amazon.com or $23 at lulu.com:

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

http://www.lulu.com/shop/marjorie-r-heesemann/chemistry-on-a-budget/paperback/product-21217600.html

The book contains 13 labs that require consumable materials you can purchase at local stores.

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. Each version is designed to be just two pages. This way the teacher can photocopy just one 2-sided page per student (saves paper).

I hope your school year is going well. Please write me to let me know about your triumphs, challenges and questions!

Have a great weekend!

0 Comments

next topic?

9/22/2014

0 Comments

Hi! I will post this Friday, 9/26, but I'm not sure what topic you would find the most useful.
In my class, I would not always go in order of most textbooks and would start with the Atom and the Periodic Table -- I realize that you may be working in the order of your department, or the textbook used. Some books get into Gas Laws now, and Kinetic-Molecular theory is a good beginning concept.

Of course there's chemistry laboratory safety -- hmmm.

So, please write to me with what you're currently teaching and what topics are next.

Thanks for your feedback!

0 Comments

element symbols & intro to chemical language

9/19/2014

0 Comments

The beginning unit of an Introductory Chemistry course typically contains the beginnings of the language of Chemistry -- the element symbols.

Unit Objectives:

Read basic chemical equations recognizing reactants, products, and suffixes to represent solid, liquid, gas and aqueous states (s, l, g, aq).
State names and symbols for elements assigned in class.

It is helpful to conduct a brief lesson to familiarize / remind your students of the language of chemistry. You could use a very simple reaction and write the reaction to show the basics of a chemical equation. One example is the combustion of methane as shown in this brief video:

I've used a larger plastic funnel to produce a larger bubble. Also, I had a student (with goggles) hold the meter stick with the candle and light the bubbles above our heads (higher than shown here).

It's a lot of fun, and then you can use this reaction to write an equation identifying reactants / products, phases and energy (also using the terms exothermic / endothermic). It's a fun way to start the language of chemistry.

You can put together this reaction component by component and explain each part as it's added:

CH4 (g) + 2 O2 (g) --> CO2 (g) + 2 H2O (g) + energy

I posted about this demonstration on January 22, 2014, and a link to the Flinn Scientific recipe for the bubble solution was posted on January 26, 2014. Check them out!

From this basic language, students can start learning the element symbols and some of the history about the table. The following page has an brief overview of the history of The Periodic Table:

http://allperiodictables.com/ClientPages/AAEpages/aaeHistory.html

The top margin of this page contains a header with various links to explore, including a link to Tom Lehrer's Element Song with a cute video!

The following interactive Periodic Table is also from this page:

http://allperiodictables.com/aptpages/apt_1_CC_Active.html

Here's a link to a blank Periodic Table -- there's a PDF you can download -- you may want to use it in class or offer extra credit for its completion:

http://sciencenotes.org/blank-periodic-table/

This page also contains several Periodic Tables:

http://sciencenotes.org/printable-periodic-table/

Here is a video song with the elements in order that's pretty fun:

The classic song is the Element Song by Tom Lehrer -- here's an animated version:

It's the teacher's decision how many element symbols for students to memorize. I felt the first 18 were a necessity, then a I selected elements to total 50 for students to know. I required correct spelling of the element names, and correct format of the symbols (capital letter, then lowercase letter if there's a 2nd letter).

A word of caution -- some students may master the element symbols quickly but have difficulty with the math of the course. These students think they are accomplishing in chemistry only to be devastated on the next quiz or test that requires math -- then meetings with guidance counselors and parents ensue.

I highly recommend that some math skills be taught/tested in the first unit so that students realize that math requirement. I am not a fan of super-challenging questions that a very small portion of the class can answer, but it is good for the students to get a taste of the realistic mathematic requirements on a regular basis.

The school year is in full swing -- I hope it's going well!

Remember that my lab book "Chemistry on a Budget" is available for $20 at amazon.com or $23 at lulu.com:

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

http://www.lulu.com/shop/marjorie-r-heesemann/chemistry-on-a-budget/paperback/product-21217600.html

The book contains 13 labs that require consumable materials you can purchase at local stores.

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. Each version is designed to be just two pages. This way the teacher can photocopy just one 2-sided page per student (saves paper).

I hope your school year is going well! Write me to let me know about your triumphs, challenges and questions!

Have a great weekend!

I

0 Comments

Density

9/12/2014

0 Comments

The first unit in a high school Chemistry course sets a foundation of Measurement, Significant Figures, and Unit Conversions. One typical concept during this first unit is that of Density.

Unit Objectives:

1. Define Density and explain how it is calculated.

2. Calculate one variable in Density = mass / volume (D = m/v) when given the other two variables.

A neat example of density changes is a lava lamp -- it's not very expensive and it's a dynamic example of the concept. (I used to have one in my classroom, but... it got stolen-- so store your stuff away!)

Here's a video discussing the concept and showing a few problems. (there is a small inconsistency in Problem #1)

For your information, from D = m / v:

v x D = (m / v) x v --> v x D = m

(v x D) / D = m / D --> V = m / D

I point out to my students that all three formulas are in "D = m/v" , it just needs to be rearranged algebraically.

Here is another video showing Density examples using a Factor-Label approach:

This Factor-Label approach aids with the units -- I have to admit, I did not solve problems this way, but I find it really helps with Volume problems.

Here are some worksheets for your class:

http://www.chsd.us/~tthompson/assignments/Physical%20Science/density%20formula%20wkst.pdf

http://www.lz95.org/assets/1/6/Denisty_WS.pdf

http://wa.westfordk12.us/pages/westfordwa_teachers/brown%20WEB/Docs/Unit%201%20CH%20Density%20Practice%20Worksheet.pdf

The following worksheet might print out a little faded, but I like the variety of questions:

http://www.bloomhs.org/ourpages/auto/2008/9/25/1222364253225/pg%2019%20and%2020.pdf

During this beginning month of Chemistry class, many Density labs can be performed safely -- this gives time to learn about chemical and fire safety and get lab safety contracts signed.

Here is a quick review of reading a graduated cylinder:

In my book "Chemistry on a Budget", there are three labs related to Density. In the lab "Density: Two Methods", the density of both regular and irregular shaped objects are measured.

Once objects are collected for these labs, you could use them the next year. Check in your Science Department to see if there's already a collection of objects used for Density labs.

The 2nd method in the lab is for irregularly-shaped objects -- the method of Water Displacement is to be demonstrated by the teacher. This video provides a reminder of this technique -- it's not concerned about Significant Figures -- you can measure to one decimal place with the graduate cylinder used:

Another density lab in my book is "Density of Three Liquids" using water, saturated salt solution and isopropyl alcohol. It will be easier to keep track of the liquids by adding food coloring.

A graph of the data collected is required in the data analysis. If you want to graph by hand, here is a link to blank graph papers for your use:

http://incompetech.com/graphpaper/square.html

I recommend drawing the points and line for one liquid before moving to the next liquid. Use a symbol around the points to differentiate the lines for the three substances (for example, circle, square, triangle). Include a Key on the graph to identify the line symbols.

Here's an online graphing program:

http://graphsketch.com/

And a sample version of Graphical Analysis is available:

http://www.softpedia.com/get/Multimedia/Graphic/Graphic-Others/Graphical-Analysis.shtml

Check in your Science and Math Departments to see if your school owns a graphing program.

One more simple lab dealing with Density and the importance of Significant Figures is "Thickness of Aluminum Foil" . It's interesting to collect the class results, maybe on the board. With those values, you can discuss the consistency of the results.

My lab book "Chemistry on a Budget" is available for $20 at amazon.com or $23 at lulu.com:

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

http://www.lulu.com/shop/marjorie-r-heesemann/chemistry-on-a-budget/paperback/product-21217600.html

The book contains 13 labs that require consumable materials you can purchase at local stores.

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. Each version is designed to be just two pages. This way the teacher can photocopy just one 2-sided page per student (saves paper).

I hope your school year is going well! Write me to let me know about your triumphs, challenges and questions!

Have a great weekend!

0 Comments

quizzes and tests

9/5/2014

0 Comments

School has begun and I am going to discuss several aspects of giving and grading Quizzes and Tests.

Calculator Policy

The New York State Regents Examination in Chemistry does not allow graphing calculators because programs can be saved that would solve various problems. For that reason, most departments I worked in did not allow the use of graphing calculators in science class.  Check with other members in your department if you are not familiar with your school policy.

Because students were juggling two calculators, sometimes they forgot the scientific calculator for a quiz or test. I eventually developed a classroom policy providing “Emergency Calculators” for students who forgot their scientific calculator. Each students could use an Emergency Calculator 1x per quarter. If the Emergency Calculator was not used, the student would earn a 100 on a homework grade.

I was able to purchase a group of six solar-powered calculators -- at the local dollar store --  to use as Emergency Calculators that I kept in the classroom.

Multiple-Choice tests

Many years ago, my cooperating teacher showed me to put a dot by the right side of the letter "C" on a multiple-choice test. You see, "C" and be turned into an A or a D if the responses are handwritten. I remember being shocked at having to do that.

Over the years, I learned to put dots not only by the C, but also by A, B, and D to show what the letter was when you graded. I don't have a picture of it right now -- imagine a box around the letter, each corner would stand for a letter.

This made it a lot easier when a student spoke to me about the quiz or test that wasn't graded correctly. If the letter was changed, I was able to tell by looking at the dot I had placed. I calmly told the student how I was able to tell, and that I was not changing the grade. If a mistake had been made, I would correct the grade.

Short Answer questions

For short answer questions, I eventually included the following instructions:

For the following mathematical problems, show all work, including unit cancellation, for full credit. Partial credit will be awarded. Circle the final answer. ANSWERS WITHOUT EVIDENCE OF A MATHEMATICAL SOLUTION DIRECTLY LEADING TO THE ANSWER WILL NOT RECEIVE CREDIT. For questions using the factor-label method, answers without work that includes units will receive NO CREDIT.

This statement was to clarify the expectation and aid in any discussions about grading of quizzes or tests.

Multiple test versions

I eventually went to two versions of a quiz or test. Yes, it's more work, but it was fair to the students who were prepared for the quiz or test. I would rearrange questions for the multiple choice section, and change starting numbers for short answer questions (typically in a Part II section).

If you are using a test generating program (many new textbooks offer the CD-ROM with sample copies), it will generate two versions of the multiple-choice test quite easily. Check in your Science Department to see if anybody already has that resource.

Blog information

Today is my first day of posting on Friday. I hope that this will give you the weekend to research the recommended resources.

My lab book "Chemistry on a Budget" (available for $20 at amazon.com or $23 at lulu.com) contains two labs dealing with Density and one about Significant Figures. I will be posting about Density next Friday, 9/12/14 and I will be mentioning those labs briefly. If you want it handy for use, order it now!

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

http://www.lulu.com/shop/marjorie-r-heesemann/chemistry-on-a-budget/paperback/product-21217600.html

The book contains 13 labs that require consumable materials you can purchase at local stores.

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. Each version is designed to be just two pages. This way the teacher can photocopy just one 2-sided page per student (saves paper).

I hope your start of the school year is going well!

BTW, I'd love to hear from you with your questions or suggestions for blog topics.

Enjoy the weekend!

0 Comments

dimensional analysis or the factor-label method

9/2/2014

0 Comments

The previous blog posts discussed the Metric system, significant figures and reviewed scientific notation. With this foundation, your students are ready to learn a very important skill, that of dimensional analysis (also known as the factor-label method).

It is a skill the also gets students used to reading measurement units and recognizing the importance of the units to calculate the final answer of any situation -- this is important in the study of Chemistry, and Physics.

I have viewed some videos showing this method, but I found them to be overly complicated. I’m going to discuss the approach here and show a few examples.

Dimensional analysis (or the factor-label method) is a way to convert measurements between systems, along with several unit changes.

A chart for reference is:

Given a value such as 51.8 ounces that need to be converted to grams, I instruct students to set up the initial conversion set-up:

51.8 ounces x __________________

where the line the beginning of the conversion factor.

Then enter the units first (the numbers will be entered later):

51.8 ounce x __________gram __
                                        ounce

The values can then be entered, and the set-up can become on big fraction:

51.8 ounce x _____1____gram __
                                 0.035 ounce


And the “ounce” unit cancels and “gram” remains:


51.8 ounce x ______ 1___gram __   =   1480 grams or 1.48 x 10 3 grams
                                 0.035 ounce


The conversion values are not considered to be limiting, so the answer would have the same number of significant figures as the beginning value (which has 3 sig figs).

The chart above also contains the equivalence 1 ounce = 28.349 grams,

so the conversion could be set up:

51.8 ounce   x   28.349 grams    =   1470 or 1.47 x 10 3 grams
                                1 ounce

Note that the last significant figure is different by one number, and that is the value that is an estimate.

A few worksheets for the introduction of this topic are:

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&sqi=2&ved=0CCMQFjAB&url=http%3A%2F%2Fwww.atlanta.k12.ga.us%2Fsite%2Fhandlers%2Ffiledownload.ashx%3Fmoduleinstanceid%3D9044%26dataid%3D44848%26FileName%3D6%2520Hwk%2520dimensional_analysis_worksheet.pdf&ei=ALoFVLuwCsaxggTpmICYCw&usg=AFQjCNHeRmLD1XWUkDLeO2f-FBkUW152aw&bvm=bv.74115972,d.aWw

http://teacherweb.com/LA/MandevilleHighSchool/Chausse/013.DimensionalAnalysisReview2.pdf

This is several pages, but has a handy description of the technique as well as problems:

http://www.flanaganhighschool.com/files/_gDDgM_/5c3bcc427e96a23b3745a49013852ec4/Dimensional_Anal_Worksheet_001.pdf

This worksheet contains some more difficult examples:

http://www.acschools.org/cms/lib07/PA01916405/Centricity/Domain/362/Dimensional%20Analysis%20Worksheet.pdf

One question that is more complicated follows:

The painter Raphaeleoeo is said to have worked at the rate of 1.0 ft2/hour. Using the factor-label method, calculate his rate expressed in cm2/century? (10) (Assume a standard year of 365 days; 100 years = 1 century)

1.0 ft 2 x    12 in x 12 in x 1 cm            x           1 cm
   Hour           1 ft        1 ft        0.3937 in                  0.3937 in

x 24 hours x   365 days x 100 year   =   8.1 x 10 8 cm 2                                           1 day          1 years         1 century            century

Another possibility for dimensional analysis practice is using conversion of currency to various denominations. The following link contains several worksheets:

http://www.wasatch.edu/cms/lib/UT01000315/Centricity/Domain/588/Currency%20Conversion%20Worksheets.pdf

You can purchase my lab book "Chemistry on a Budget" through amazon.com and lulu.com for only $20! The book contains 13 labs that require consumable materials you can purchase at local stores.
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. Each version is designed to be just two pages. This way the teacher can photocopy just one 2-sided page per student (saves paper).

I hope your start of the school year is going well!

I am changing the day of my new blog posts to Friday – this is to give you the entire weekend to read the new post. My next post will be this Friday, September 5th.

BTW, I'd love to hear from you with your questions or suggestions for blog topics.

Enjoy the rest of the week!

0 Comments

Blog Topic List

next topic?

element symbols & intro to chemical language

Density

quizzes and tests

dimensional analysis or the factor-label method

Author

Archives

Categories