Element of the Day Electron micrograph
Os
http://www.youtube.com/watch?v=AdX­T2Vv68Y
Osmium (oz­mee­әm) is a chemical element with the symbol Os and atomic number 76. It is a hard, brittle, blue­gray or blue­black transition metal in the platinum family and is the densest natural element, with a density of 22.59 g/cm3. It is found in nature as an alloy, mostly in platinum ores; its alloys with platinum, iridium, and other platinum group metals are employed in fountain pen tips, electrical contacts, and other applications where extreme durability and hardness are needed.
Osmium is a hard but brittle metal that remains lustrous even at high temperatures. It has a very low compressibility. Because of its hardness, brittleness, low vapor pressure (the lowest of the platinum group metals), and very high melting point (the fourth highest of all elements), solid osmium is difficult to machine, form or work.
Oxidation results in an increase in __________ while reduction results in a decrease in ________.
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Chemistry
1. Element of the Day ­ Os
2. Turn in Laboratory Investigation
3. Lecture on Batteries 4. Batteries POGIL
5. Start Homework
Announcements
Due Today: Redox POGIL Activity and Laboratory Assignment.
Due Monday: Finish Battery POGIL activity, read pages 537 ­ 544, and finish practice quiz.
Quiz on Redox Reactions delayed to Monday.
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Name:
Date: April 10, 2012
Title: Electrochemical cells
Partners: ________________
I. Question: Why do combinations of metals produce different voltages?
II. Procedure
III. Data Table
Ag
Cu
Mg
Pb
Zn
Ag
Cu
Mg
Pb
Zn
IV. Observations
V. Analysis Questions: 1) Use info from your data table and your knowledge of reactivity to write half reactions for each pair of metals. Then write full reactions for each pair of metals and identify the cathode and the anode.
2) How is the difference in voltage similar to the relative positions of the metals in the activity series from the last lab? Explain your answer.
3) Briefly describe energy transfers and transformations during electrochemical reactions.
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Submit Laboratory Assignment and Redox POGIL
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Activity Series
Most Reactive
Mg
Zn
Pb
Cu
Ag
Reactivity = likely to be
oxidized. (give up electrons)
Least Reactive
Oxidized half reaction:
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Reaction:
• Half
• Overall:
Energy Diagram: 6
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Electrolytic Cell
Reaction:
• Half
• Overall:
Energy Diagram: 8
Sodium–sulfur battery
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Chemistry Lab Groups
Group 4
Group 1
Matthew R
Alderson
Daniel J
Connelly
Bill Lee Catherine E
Edwards
Dakota P
Rice Tiffany P
Lee Martin W
van Drunen
Group 5
Group 2
Dominique D'Onofrio Taylor Ahliquist
Anthony H
McMillan
Sara Turpen Timothy D
Taylor
Annika J
van Houte
Group 3
Indigo M
Larson Aidan K
Moore
Spencer T
Alpaugh
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Exit Question
What are the two mnemonics to help us remember what occurs during redox reactions?
Reminders
Due Monday: Finish Battery POGIL activity, read pages 537 ­ 544, and finish practice quiz.
Quiz on Redox Reactions delayed to Monday.
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