Evidences of Chemical Reactions - the KNOWLEDGE


1. Gas forms (bubbles)

2. Color change

3. Heat change

4. Precipitate forms

5. Light is given off

6. Electrical potential generated



"yields" or "goes to"


separates two reactants or two products


substances in gases state


substance is dissolved in water


substance in liquid state


substance in solid state



Chemical reactions are typically presented in the following manner:


_____ Reactants____ à ___ Products___

Starting Substances New Substances


The Balancing Act


aluminum + copper II sulfate à aluminum sulfate + copper


__ 2_ Al + _ 3__CuSO 4 à __ 1__ Al 2(SO 4) 3 + __ 3__ Cu



Draw a “sticks and spheres” model of the above reaction, making sure to have the correct number of molecules and atoms represented.




Rules for Balancing Equations:


1. Write the SKELETON equations, either word or formula, to represent the facts. (Use the

types of reactions table.)


2. Determine the CORRECT formulas for all the reactants and products.


3. Write the FORMULAS for the reactants on the left and the formulas for the products on the

right with an arrow in between. If two or more chemicals are involved, separate their formulas

with “+” signs.


4. BALANCE the elements one at a time by using COEFFICIENTS .

(Coefficient - a small whole number that appears in front of a formula in an equation.)

NOTE: Do not attempt to balance an equation by changing the subscripts in the chemical formula of a substance !!!!!