VI.1 Chemical Equation

Purpose: to understand what is chemical reaction equation and remember details in the equations.

As we know, chemical reaction means there are new substances be produced. But when chamical reations occur, it aslo follow by physical reactions. For instance, colours of materials, the temperature and new states may be formed.

CHEMICAL REACTION EQUATION: an equation that shoes the chemicals used up and produced during a chemical reaction.

General form:REACTANTS PRODUCTS

EX: coeff.gif http://www.google.com.hk/imglanding?q=chemical%20equation&imgurl

COEFFICIENTS: numbers in front of the symbols

The meaning of "": reacatants exits, then as time passes products exist. (We also use words to show reactants and products, that is called CHEMICAL WORD EQUATION.)<From the book on P105>



VI.2. The Conservation Laws

Purpose: --understand the meaning of system (closed and open system)
--understand what is conservation laws and know how to identify each of them


PART1

Vocabulary:--SYSTEM: the part of the universe being studied in a particular stituation.<From the book on P105>
  • Closed system: things cannot get into/out of it
  • Open system: things can get into/out of it
Examples:
A beaker full of water is an example of OPEN system when the water is considered to be the "system". Because the heat can get into the beaker and water, so that makes the water vapoured to the air.But if the beaker is seal which nothing can get in or out of the tube, so that is the CLOSED system.


PART2

Vocabulary--CONSERVED: the quantity doesn't change when a reaction happened--the system is closed
--
CONSERCATION LAW:
Naming of the law of conservaion
Thing does not change in a closed system during a chemcal reaction
The law of conservation of MASS
Total Mass
The law of conversation of ATOMS
Total number and type of atoms
The law of consercation of ELECTRICAL CHARGE
Total electrical charge
The law of conservation of ENERGE
total amount of energe
EXERCISES:
1. Identify which consercation laws are being broken in the following situations? (It is not necessarily be broken)

a). 3H2O+O2→3H2O
b). NaOH+H2SO4→Al2(SO4)3+H2O
c). At STP, 10.0g of chlorine gas and 28.0g of oxygen gas produce 38.0g of chlorine dioxide gas.
d). Fe3+ + S2- →FeS


2. Which of the following are conserved in a chemical reaction?
a) temperature b). phase c). total mass d). moles


Answers:
1.a). The law of conservation of ATOMS
b). The law of conservation of ATOMS
c). The law of conservaton of MASS
d). The law of conservation of ELECTRICAL CHARGE

2 (c)