For the next series of experiments:
- Nikolay Anya Rose
- Aanya Jagan
- Akshay Jin Young
- Nigel Mona
- Shiv Isabella Jesus
- Harshita Lucas
- Nahuel Varun
- Jay Ethan
- Maya Ahaan
- Deacon Rino
- Eva Yususke
- Ji Soo Driena
- Dong Ha Eun Young
- Sang Hyun Andrea
Notice how he mentions the balance as an essential instrument for the development of chemistry. Today we embark on a series of investigations that parallel the idea that what happens to mass during chemical transformations is a fundamental pattern in the behavior of matter. This pattern is explained by the characteristics and behavior of atoms and molecules. (You will be adding to your chart of observations–evidence and argument–atomic-molecular theory.)
It is absolutely necessary to weigh things carefully to get good data. Check zero, keep things clean, do not spill, record results accurately and completely (with labels). You always need to think of the order of weighing things. You always need to take account of containers that need to be used and weighed. Even a small paper cup to hold some chemical powder must be weighed.
Always write what you expect to happen and why before you begin. You may call this an expectation.
Take good notes. Organize and label your data. Take pictures. Make sketches. Record your thoughts and questions as you go. Discuss your ideas with your partner. Share data with each other.
- What happens to the mass of an ice cube after it changes into liquid water? (Nothing is allowed to escape; nothing is added)
- Find the mass of a clean, dry canning jar with a tight fitting lid.
- Add an ice cube, seal the lid, and find the mass.
- Let the ice cube melt, wipe the outside of any condensation, be sure the balance is clean and dry, and find the mass again.
- Enter data in your own notes.
- Enter data on class spreadsheet.
Steel Wool and Vinegar
- What happens to the mass of steel wool and vinegar (steel wool is immersed) kept in a closed container?
- Remove the label if there is one on a plastic pop bottle. Label with masking tape, your names, period, date, time, steel wool and vinegar.
- Find the mass of the newly labeled bottle and lid.
- Get a piece of steel wool. Ask Dr. F about the size. Find the mass. Put the steel wool in the bottle.
- Get an amount of vinegar that is sufficient to cover the steel wool. (No steel wool should stick out above the surface of the vinegar.) Find the mass of the vinegar.
- Find the total mass of the bottle, tightly screwed on lid, steel wool, vinegar, (and air that is in the bottle).
- Be sure to record your expectations, all data in your notes and in the class spreadsheet, and to take pictures.
Steel wool and moist air
Get a piece of steel wool that has been soaked in vinegar to remove the coating of oil that is part of the process of marketing steel wool. Check with Dr. F for the size.
- Label a bottle with tape. Names, period, date, time, steel wool and air.
- Find the mass of the bottle, label and lid.
- Weigh the bottle with steel wool, moist air, tightly fitted lid.
- Record data appropriately, as above. Be sure to record your expectations.
Mung beans in moist towel
- Label a bottle with tape. Names, period, date, time, mung beans in moist towel.
- Find the mass of the bottle, label, and lid.
- Find the mass of a dry spoon full of mung beans.
- Moisten a paper towel and make a roll with the beans inside.
- Add 1 ml water to the bottle. Insert the paper towel with bean into the bottle, tighten the lid.
- Find the total mass of the bottle, beans, paper towel and lid (closed tightly).
- Record data appropriately (as above).
Baking soda and vinegar in an open bottle
- Write what you expect to happen to the mass after the vinegar and baking soda have reacted.
- Weigh a bottle without a label and lid.
- Weigh 2 grams of baking soda.
- Weight 40 grams of vinegar.
- Weigh bottle, baking soda, and vinegar together but without mixing.
- Add baking soda and vinegar to bottle. Do not spill anything.
- Weigh bottle, contents after the vinegar and baking soda have completed reaction.
- Compare the total mass before the reaction and the total mass after. Find the difference.
- Record data appropriately as above.
Link to data spreadsheets. Let me know when you are ready and I will give you editing privileges. https://drive.google.com/drive/folders/0B4DPwlouN3dIRmJyTE9zd2t3M3M?usp=sharing
See these two episodes from The Ring of Truth: An Inquiry into How We Know What We Know (Change)
Full Chapter Change: https://www.youtube.com/watch?v=Nk8CQNThbc0