Science 8 Period 6 Dr. Frazier 12 October
Follow this sequence today and the next class if necessary:
Always record your expectations BEFORE carrying out any lab procedures. Always justify in writing the procedures you propose to carry out. Always record the ACTUAL procedures you perform. Always record you data completely in a well-organized, well-labeled format.
- Observe and record the details of generating and collecting the gas from the alka-seltzer and water reaction.
- Make note of your ideas for testing the gas. How, for example, could you determine the density of the gas with respect to air?
- Carefully weigh out 0.2 grams of baking soda. Place in a plastic petri dish.
- How much vinegar will take to react completely with the mass of baking soda—so that all the baking soda has reacted AND all the vinegar (a 5% solution of acetic acid and water) has reacted?
- What can you observe to know that each substance has completely reacted?
- What is the proportion of baking soda to vinegar for a complete reaction? Test your estimate with different amounts.
- Determine the amount of gas (mass and volume) given off by 5 grams of baking soda and the quantity of vinegar that will react completely with the 5 grams..
- What gas is produced by the reaction between vinegar and baking soda? How does it compare to: air, the gas left in the cylinder after the steel wool had reacted/rusted (nitrogen), the gas that formed from the alka-seltzer and water reaction?
- Find out the molecular structures of baking soda and acetic acid. Use the balls and sticks to create a model of the reaction. Take a series of pictures in order, showing the simplest set of changes to rearrange the reactants (baking soda and acetic acid) into the products (?).
HW: Get notebook up to date with reflections. Read about the award for the Nobel Prize in Chemistry. Write a response in your notebook. http://www.nytimes.com/2012/10/11/science/2-american-scientists-win-nobel-prize-in-chemistry.html?_r=1&emc=eta1
Additional notes for 16 Oct:
Find out about fermentation (with regard to question on how vinegar is made):
1. Grape juice to wine by yeast; without oxygen present–anaerobic and using enzyme in yeast: C6H12O6 (glucose) → 2C2H5OH (ethanol) + 2CO2 (carbon dioxide))
2. Wine (ethanol) to vinegar by bacteria: (C2H5OH + O2 → CH3COOH (acetic acid) + H2O)
Reference for air chemistry and climate from the National Center for Atmospheric Research: https://ncar.ucar.edu/learn-more-about/pollution
An answer to the proportion question about vinegar and baking soda; can you follow it? http://www.newton.dep.anl.gov/askasci/chem07/chem07486.htm