Showing posts with label Ross. Show all posts
Showing posts with label Ross. Show all posts

Wednesday, December 8, 2010

12/8/10

Announcements: do your homework and study! Quiz tomorrow!
Homework: Complete chemthink tutorial and quesitons (chemical reactions)!

On this day (late arrival) we learned about different reaction types:

1) Single Replacement
2) Double Replacement
3) Synthesis
4) Combustion
5) Decomposition

During single replacement, one element replaces another element in a compound. This kind of reaction consists of three elements: AX+Y. In this case A and X attract because they have the opposite charges (+ and -) while Y has a possitive charge. During single replacement, the product will end up being AY+X because now element Y has replaced element X. Example:

Since both copper and iron have a positive charge, they switch.

During double replacement, the positive charged elements and the negative charged elements switch places. This kind of reaction contains 4 elements: AB+XY. In this case A and X have positive charges and B and Y have negative charges. During the reaction, these elements switch pairs: AY+XB. To make it simpler, here is another example. There are two couples: AB and XY. A(boy) decides he doesn't like B(girl) and starts dating Y, and vice versa. Another example:


During synthesis, a 2 elements join together to form a complex compound. This reaction type is much easier to learn. An example: A+B=AB.

During decomposition, a complex compound seperates into two elements. Its the exact opposite of synthesis. An example: AB=A+B

Combustion is the reaciton of oxygen gas with anything. Combustion always and only contains oxygen carbon and hydrogen. It is the easiest reaction to learn because the answer is always CO2 + H2O. After this, all you have to do is balance the equation. Example:

Next scriber... IS PEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEETER I.

Wednesday, October 13, 2010

10.13.10

Wednesday: late arrival! :) 35 min period

At the beginning of the period, Mr. Paek showed us a few vidoes on metal reactivity. He explained how the periodic table consists of different families:
Row 1(downward) - Alkali metals
Row 2(downward)- Alkaline earth metals
D Block(sideways)- Transition metals

The vidoes consisted of experiments about the reactions of the alkali metals and water. The farther down the row in the periodic table, the stronger/more intense the reaction. In one of the videos, it included an experiment with a glass. The metals were put in the water one by one:
Li- Floated on the water while giving off hydrogen
Na- The same as Li, but a more vigorous reaction. Na gave off much more hydrogen
K- Produced sparks and a small fire
Rb- Produced bigger sparks and bigger fire
Cs- Completely shattered the glass cup

After watching the vidoes, Mr. Paek introduced a short lab. The metals that were being tested were calcium, magnesium, and aluminum. We placed these metals into well plates and used water, HCL, phenolphthalein indicator (PHTH) (liqiud) to see how they would react with the metals. Her is the data:
Appearance:
Ca- little rocks
Mg- thin metal sheets
Al- Flat rocks

PHTH:
Ca- water turns pink
Mg- magnesium sheet turns pink
Al- water becomes cloudy

Water:
Ca- sizzles and dissolves
Mg- nothing
Al- nothing

HCL:
Ca- sizzles and disolves a little
Mg- sizzles and gives of hydrogen
Al- nothing

PHTH and HCL
Ca- turns pink
Mg- nothing
Al- nothing

NO HOMEWORK!!!
Next Scriber: Sal :)