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Gas Law Analysis

The purpose of the labs was to determine how pressure, temperature, and volume were related in a gas.

Make your learning a conversation with others!  You have watched demonstrations, read txt, practiced gas law equations, and done some labs. Now you must take all this learning and write an analysis, a conversation of what you learned. This analysis must be posted on your chemistry blog.

Write your analysis as a discussion or a story. Please do NOT write your analysis as a list of answered questions, even though you have been given a list of questions.  You will be assessed on 1) knowledge of the subject material; 2) describing the material in your own words and in an interesting manner; and 3) personal contribution to the topic.

Labs you have done related to the gas laws are:

Hot Balloon:  An Erlenmyer flask with approximately 50 mL of water in it and a balloon secured on top is heated, and the circumference of the balloon is measured before and after heating the water.

Cartesian Diver: A 2-liter soda bottle is filled with water and a medicine dropper placed inside. After being capped, the bottle is squeezed.

Soda Can Crush:  A soda can with a small amount of water in the bottom was heated on a hot plate, and then flipped with tongs into ice water.

Pressurized Balloon:  A 2-liter soda bottle that has a balloon inside was pressurized.

Pressure and a Bag:  Two large jars with plastic bags taped over the mouths, one inside and the other outside.

Demonstrations you have seen related to the gas laws include the Bell jar vacuum. Individually, the following were exposed to a vacuum under the bell jar:  glass of water, balloon, marshmallow, shaving cream, empty water bottle.  You also saw the press of air against an evacuated metal sphere with handles.

Need help with definitions?  WyzAnt has a decent tutorial here.

Stoichiometry Help

images (1)

Interactive Practice with stoichiometry problems:

“That which you persist in doing becomes easy to do – not that the nature of the thing has changed, but your power and ability to do has increased.” — H.J. Grant

Goal: Be able to use the law of conservation of mass to write balanced chemical equations, identify the basic types of chemical reactions, and predict the possible products from a given set of reactants.

You must demonstrate your achievement of this goal.  In a blog post, (1) explain how to balance an equation and why it is important, and (2) describe different labs you did, what type of reaction it was, and provide a balanced reaction for each.  You have done synthesis, decomposition, single-replacement, and double-displacement labs.

You must also (3) describe how to predict the possible products that will occur from a given set of reactants, and (4) demonstrate your ability to predict reaction products.

As of the first week of March, chemistry students have conducted the below list of chemistry labs. Use this list to support your evidence of attainment of the above goal.

  1. Baking Soda to Salt Lab
  2. Limiting Reactants Lab
  3. Chemical Reactions Webquest
  4. Three Types of Chemical Reactions
  5. Reactivity of Metals
  6. Hydrate Lab
  7. Molecules of Candle Burned
  8. Molecules of Chalk In Your Name
  9. Covalent or Ionic Bonding Lab
  10. Halides Lab
  11. Periodic Trends
  12. Ionic vs Covalent
  13. Half life of Candium
  14. Isotopes of Vegium Lab
  15. Rutherford Lab
  16. Law of Conservation of Mass
  17. The quality of Laboratory Measurements
  18. Measuring Stuff: Tools and Skills
  19. Density Problems
  20. Lab Skills Lab
  21. Observations Lab

Snow Days

How Should We Make Up Lost Time On Learning?

The headline reads: Boston in midst of snowiest 30 days on record!

Schools in eastern Massachusetts have experienced an inordinate number of snow days– ten in my school by mid-February– and students have been losing valuable learning time. Students not only lose time but they lose the momentum of learning; interruptions in schedule means that the instructor must review and repeat before continuing with the lesson.
If schools take the traditional route of tacking days onto the end of the school year, children will be in school until the last day of June. For some this may not be a problem, but there are many reasons for not taking this standard approach.

  • High school seniors have a graduation date that allows them to get out earlier and do not make up missed days, thus they lose those education hours. Ten snow days results in a 27% loss of learning time for seniors taking a semester course.
  • Other high-schoolers “check out” and lose focus during June and after the seniors graduate. One student phrases this as “At my school, we stop learning new material for the most part around midway through May”, and while I disagree about his statement it has been my experience that the students lose focus at the end of May.
  • Many families have pre-set plans for their summer and will take their children out of school to keep their schedule.
  • There are many scheduled exams that students must take and lost snow day hours are added AFTER the exam date will not help them at all. AP exams are the first two weeks in May.  The ELA MCAS exam is March 25th and 26th, the math MCAS is May 12th and 13th, and the science MCAS exam is June 2nd, all of which a student must pass to obtain a high school diploma.
  • Teachers must take summer courses to maintain their certifications and many courses begin at the end of June.
  • Many teachers work a summer job to help support the family.

21st Century education moves beyond standard practices and asks students to be creative, innovative, collaborative, and think outside the box. We should too. Instead of tacking school days onto the end of the year, which will not help students with their state and national exams, or asking students to make up the days on Saturdays or April vacation, which would result in a very low attendance particularly at the high school level, schools should incorporate creative and flexible methods for retrieving the learning time for students. Here are some off-the-top-of-the-head ideas and I’m sure there are many others:

  • ELearning! Children are already consuming information through their smartphones, iPads, and laptops, let’s take advantage of that. Online supplemental work could be either independent and on the student’s schedule or it could be scheduled with the teacher present on the other end. Seat time is recorded by the log-in and actions of the student. The examples are endless.  Delphi school in Indiana requires students to log on during snow days. Farmington district in Minnesota uses their “Schoolology” digital platform, and Pentucket Regional School District could use their “Schoolloop” digital platform.
  • Relevant work packets sent home with students that they can do on their own schedule and will count as a given set of hours when turned in. Other states, like New Hampshire, Minnesota, and Ohio have “blizzard bags”, which Burlington and Wayland schools have taken up.  This link goes to Contoocook Valley regional schools as an example of one way a blizzard bag could work.
  • Extend the school day one day per week by two hours, adding time to all subjects.
  • Move teacher professional development out of the student’s education time to Saturdays or the end of the year.

Teachers, administrators, and unions need to work cooperatively together to make this school year meaningful and authentic. To get to the job of educating children, let’st stop making excuses for why something CAN’T be done and look at how it CAN be done.

Objective: Create a web diagram that illustrates environmental, social, and economic impacts associated with an everyday item.

Recent class discussion has considered the concept of our “ecological footprints” and the impacts of a given lifestyle on people and societies. Today, with a partner, you are to develop ideas to reduce the ecological footprint and associated impacts related to an everyday item.

impacts of a burger

Starting point for discussion of hamburger; incomplete.

Steps to get you going:

  1. Brainstorm and diagram all the resources, processes, and impacts associated with one everyday object, such as an item of clothing, a favorite meal, or a piece of sports equipment. For example, if you decide to diagram the impacts of a cell phone, you would write and/or draw the resources and processes required to produce each part of the phone and all the impacts you can think of that might be related to both producing it and using it.  The Good Stuff? – A Consumption Manifesto: The Top Ten Principles of Good Consumption may give you some ideas of what to watch out for. You have five minutes for this brainstorming step.
  2. Once you have decided on one item to be the focus of your impact diagram, diagram your impacts on  Prezi. Remember to consider impacts related to transportation of a product, marketing, health issues, and waste disposal. You might also want to organize your thoughts on a chart such as the one below, to help you and your partner keep track. Additional resources for research are given below. This step should take about 20 minutes.

    Brainstorm Chart

    Organize Your Thoughts

  3. Brainstorm and list ways to reduce the ecological footprint and other impacts associated with creating or using the product. This will take 5 – 10 minutes.
  4. Publish your work! You will need to publish both your Prezi and a description and link to it on your blog.
  5. Tomorrow, you and your partner will present your diagrams and proposed ideas for reducing the item’s negative impacts on people and the planet.

Analysis

After presentations have been made you will consider and write about the following:

  1. How is the ecological footprint of a person’s lifestyle connected to social and economic impacts?
  2. Would production, use, and disposal of these everyday items be sustainable if only a small number of people purchased the items?
  3. How would the impacts associated with an item change if everyone in the world purchased or used it?
  4. Does lessening our impacts necessarily mean reducing our quality of life? Why or why not?
  5. How might businesses be encouraged to produce these items in ways that have more positive impact on the environment and on people?
  6. Often negative impacts associated with an item are not paid directly by the people who purchase and use the items. Who might end up payiong for those impacts? Why do you think these impacts are not included in an item’s purchase price?

Resources

The Life Cycle Of A Cell Phone
The Life Cycle of a CD or DVD
The Hidden Life of Paper and Its Impact on the Environment
The hidden cost of your hardwood floor
 Global Exchange Website: Fair Trade Coffee

This lesson for environmental science students is a modification of “Buy, Use, Toss” from Facing The Future.

This past month chemistry students have been learning how to convert between grams, molecules, and moles, so each day the bell-ringer/do-now/QOD assignment was a calculation of molecules of something familiar: chalk, candle wax burned, nicotine, aluminum foil, etc. I believe that each day’s practice helped solidify their understanding of the concept. So one day I asked how many molecules in a snow flake. Since we had to start with a mass, and I did not have time to determine the mass of a single snowflake, I turned to the internet and found Archimedes Notebook: How much does a snowflake weigh?  Thus, I gave the students the following information

Most snowflakes weigh from 0.001 to 0.003 grams, with a heavy snowflake coming in at 0.02 grams. Choose a mass within that range and calculate the number of molecules of water in the snowflake.

Thus, different students came up with different numbers of molecules, giving us a range of data.  Note:

The largest snowflake ever seen was 8 by 12 inches and was reported to have fallen in Bratsk, Siberia in 1971.

Most students elected to use the average of the lower two numbers, and calculated as follows:

mol snowflake

That is a lot of molecules. Adding or subtracting just one molecule of water would result in a unique snowflake. And considering that water is a polar molecule, the hydrogen bonding arrangement possibilities is mind boggling.

Then we have to consider factors that affect how a snowflake develops. NOAA gives this simplified explanation, which still is not the entire story:

A snowflake begins to form when an extremely cold water droplet freezes onto a pollen or dust particle in the sky. This creates an ice crystal. As the ice crystal falls to the ground, water vapor freezes onto the primary crystal, building new crystals – the six arms of the snowflake.

…The intricate shape of a single arm of the snowflake is determined by the atmospheric conditions experienced by entire ice crystal as it falls. A crystal might begin to grow arms in one manner, and then minutes or even seconds later, slight changes in the surrounding temperature or humidity causes the crystal to grow in another way.  ~ NOAA

From snowcrystals.com we get a bit more information:

Snowflake Morphology

Snowflake Morphology

We see that thin plates and stars grow around -2 C (28 F), while columns and slender needles appear near -5 C (23 F). Plates and stars again form near -15 C (5 F), and a combination of plates and columns are made around -30 C (-22 F).  Furthermore, we see from the diagram that snow crystals tend to form simpler shapes when the humidity (supersaturation) is low, while more complex shapes at higher humidities. The most extreme shapes — long needles around -5 C and large, thin plates around -15 C — form when the humidity is especially high.

PBS tried to get a definitive answer to this question “So is it really true that no two snowflakes are alike?” from physicists Kenneth Libbrecht, a physics professor at the California Institute of Technology and avid snowflake photographer, and John Hallett, director of the Ice Physics Laboratory at the Desert Research Institute in Reno, Nev., and got the following response:

“It’s like shuffling a deck and getting the exact same shuffle for 52 cards,” Libbrecht said. “You could shuffle every second for the entire life of the universe, and you wouldn’t come close to getting two of the same.”

So, there you have it. While not impossible, it is highly unlikely given that there are a trillion, trillion, trillion (a 1 with 36 zeros!) different types of snowflakes.

A Chemistry “Do Now”

Mole map

How much chalk does it take to write your name?

Figure this out!

Step 1. Mass a piece of chalk.

Step 2. Use this chalk to write your name on the board.

Step 3. Remass the chalk.

Step 4. Convert grams to moles, using the grams of chalk used.

Hint: Chalk is calcium carbonate, CaCO3

Step 5. Convert moles to molecules.

Step 6. Write and communicate everything you did and discovered in a visual.

moles_too_many

Click on the image!