Reflection: Safety Conservation of Mass Lab - Section 5: Elaborate (homework)


As most science teachers are aware safety is the number one concern in the class, especially when a lab is being conducted.  This lab is no exception.  I chose this lab over the "traditional" baking soda and vinegar conservation of mass lab because it provided student with a real world look at how chemical reactions occur around us on a daily basis in the form of rust.  And just because something appears physically and chemically different, mass is still conserved during a chemical reaction.  

I would have like to made this lab more visually noticeable (increase in gas production) by using a stronger concentrated acid, such as 6 M sulfuric acid. By doing this students would see more product made and therefore a greater mass difference between reactants and products in trial A when gas was released into the air.  In addition, in trial B the greater mass of the gas would inflate the balloon more.  

In my mind the payoff for better results was not worth the potential safety issues that might occur when students try putting the balloon on the flask.  I have see in the past that the potential for tipping the flask can occur when students attempt to affix the balloon to the flask and with a stronger acid the potential for an burn is greatly increased.    

Using a lower concentration acid can lead to a discussion about lab safety and how results can sometimes be hard to measure.  This can also lead into a conversation about using classroom data to gather more reliable data.  

  Lab Safety
  Safety: Lab Safety
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Conservation of Mass Lab

Unit 3: Unit 5 Chemical Reactions
Lesson 6 of 13

Objective: SWBAT model, identify and balance chemical reactions demonstrating the Law of Conservation of Mass.

Big Idea: Students conduct an investigation that shows mass is conserved during the chemical reaction between sulfuric acid and steel wool (iron).

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rusted bridge
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