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.