12 October Science 8 Chemical reactions–Organizing our observations and connecting them/explaining them with the Atomic Theory of Matter

  1. Mindful moment.
  2. Previous DSN entry. Be sure you are keeping up.
  3. Preview plan for today on blogpost. Pay close attention to experiments and procedures.
  4. Create entry in your DSN for today in the matter folder.
  5. Questions.
  • * * * * *

A.With your partner, get a microscope, slide, and small piece of copper. Place the copper on the slide and bring it into focus on the lowest power. Try to take a picture with your ipad. When you are ready, we will put a drop of silver nitrate solution on the copper piece on the slide. Continue to observe carefully. Take pictures as you can. What do you see happening.

Timelapse by Denzel C. period 8 Science 8 10 October, 2018: <https://drive.google.com/file/d/1FAY6QMXNpnwFwAf62qLE-mIpTG9nptEr/view?usp=sharing>

Here is a depiction of the reaction. S means solid. Aq means aqueous–in water–a solution:

copper + silver nitrate → copper(II) nitrate + silver
Cu(s) + 2AgNO3(aq) → Cu(NO3)2(aq) + 2Ag(s)

The numbers give the ratio of atoms that combine. Notice that the same number and kind of atoms appear on each side of the reaction. This is why this expression is called an equation.

Try a similar observation with a piece of zinc. Here is the reaction equation:

Zn(s) + 2AgNO3(aq)Zn(NO3 )2 (aq) + 2Ag(s)

B.Let’s try to observe Brownian motion.

We will examine Brownian motion of fat globules in milk. See what you can find out about Brownian motion. The technique will be described in class.

See the videos showing Brownian motion of fat globules in milk. Apologies for the camera motion. The videos would have been better with a fixed camera. Nevertheless, it is possible to see the random movement of the fat globules. How is this movement interpreted in light of the atomic/molecular theory of matter? (Note: a microscopic fat globule is composed of a truly enormous number of too-small-to-see molecules–according to the theory.)

Video https://drive.google.com/file/d/0B4DPwlouN3dIRHQ0NUw5RWtpNzg/view?usp=sharing

Video by Aadi and Sumair period 8:

For C and D below you will need two plastic bottles. Remove the label. Rinse them with water. Dry the outside thoroughly. You do not have to dry the inside. Put a piece of masking tape on the outside to serve as a label (name, period, data and time, which experimental condition)

C. Place a bit of the steel wool (that has had the coating of oil removed by soaking in vinegar) into a plastic drink bottle with a few drops of water. Close the lid tightly. Dry the outside of the bottle completely. Write your names, period, date, time, and steel wool in moist air on a piece of masking tape and place on the outside of the bottle. Find and record the mass of the bottle. We will examine you bottle next week. Be sure to include your expectations in your DSN entry for today.















Enter your data: https://docs.google.com/spreadsheets/d/1rrd1tHdwl83TcklHU6S69Y0vZFU4qgvQ5qrY-VYF2ng/edit?usp=sharing

1718 Class spreadsheet: https://docs.google.com/a/aes.ac.in/spreadsheets/d/14FwGAKLDQq807T-ntdtD4Rp2dzveqX8HuAk3eunY2ws/edit?usp=sharing

D. Place a bit of steel wool into a bottle. Ask Dr. F how much. Cover the steel wool with vinegar. Tighten the lid. Dry the outside of the bottle. Label with tape–names, period, date, time, and steel wool immersed in vinegar. Find and record the mass of the bottle. We will examine your bottle next week. Be sure to include you expectations in your DSN entry for today.











Enter your data: https://docs.google.com/spreadsheets/d/1tgEamXHYw64OTPBVGCRu3U9CtvMZCk5lz0oIpvgRqgQ/edit?usp=sharing

1718 Class spreadsheet: https://docs.google.com/a/aes.ac.in/spreadsheets/d/1_UM-F_4LSQtvW3e4PaJiFknqv0wamDnNJbtHj6x2e3c/edit?usp=sharing

E. Examine the crystal growth. Have any formed in your dishes? What do you notice about their shapes? Can you see an underlying pattern? Take pictures and make sketches. If you have not already watched this, do so before our next class:

What do crystals suggest about atoms? See this short video:

Mathematical Impressions: Attesting to Atoms


Create and complete this chart with our class investigations to date (SEE TODAY’S BOARD):

Consider these big questions (KEEP IN VIEW-KIV QUESTIONS AND IDEAS):

  • What can we observe about the structure and behavior of matter?
  • How can we explain what we observe (at the scale of our senses) by structures, entities, and behaviors at a scale we cannot see?
  • How can such explanations be tested?
  • How can we tell if the atomic theory of matter is a workable/reasonable theory?

List all the activities and investigations

we have carried out with matter.

How can these be explained in terms of

the behavior and properties of atoms?

A few examples of large scale observations:

  • Water changing state. Temperature plateaus.
  • Salt water evaporating more rapidly than fresh water.
  • Conservation of mass–mass of ice  equals mass of melted water.
  • Crystal form of Sodium Chloride.
  • Solutions of magnesium sulphate and sodium carbonate reacting.
  • Vinger and baking soda reacting.
  • ETC.
  • The video recommended earlier in the year demonstrates how to take an observation of matter in the large scale and explain it in terms of what happens on the atomic scale. You should watch it if you have not already AND it is good to watch again: From The Ring of Truth by Philip Morrison. Atoms: https://www.youtube.com/watch?v=WQ3mjb9BSaU



About rfrazier

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