Chapter 6, Sections 1 & 2 Pages Describing Chemical Reactions

What is a Precipitate? A solid that forms from solution during a chemical reaction. Figure 4, page 218

Endothermic vs. Exothermic An endothermic reaction takes in energy. (fig. 5, pg. 220) The energy enters. An exothermic reaction releases energy. (fig. 6, pg. 221) The energy exits.

What are Chemical Equations? An easy way to show a chemical reaction. Summarize chemical reactions by using chemical formulas and other symbols. Figure 8, pg (draw ) CaCO 3 yeilds CaO + CO 2 Symbol Formula Subscript

Draw!!!

Conservation of Matter During a chemical reaction, matter is neither created nor destroyed. What other laws does this sound like??? If you cant destroy matter, can you destroy atoms?

Open vs. Closed System In an open system, matter can enter from or escape to the surrounding area. Example: Wood burning in a fireplace. In a closed system, matter cannot enter or leave. Example: A pear in a glass dome. Figure 10, pg. 227 (draw) Open System

Balancing Chemical Equations An accurate Chemical equation shows both sides of the equation equal, having the same number of atoms on each side. Look at the examples on pages Coefficient : A number placed in front of a chemical formula to balance both sides of the equation. (draw).

Classifying Chemical Reactions The three types of general chemical reactions are synthesis, decomposition and replacement. (draw) Figure 11, pg. 230.

Synthesis When two or more elements or compounds combine to make a more complex substance. Opposite of Decomposition Figure 11, pg (draw) Examples: 2H 2 + O 2 2H 2 O 2Mg +O 2 2MgO

Decomposition Occurs when compounds break down into simpler products. The opposite of synthesis Figure 11, pg (draw) Examples: 2H 2 O 2 2H 2 O + O 2

Replacement When one element replaces another in a compound, or when two elements in different compounds trade places. Figure 11, pg Examples: 2Cu 2 O + C4Cu + CO 2 2Fe 2 O 3 + 3C4Fe + 3CO 2

Questions???