1. Chemical Equations
Chapter 6

2. How do we know a chemical reaction has occurred?
The color changes.
A solid forms.
Bubbles form.
Heat and/or a flame is produced, or heat is absorbed.

3. Vocab.
A chemical change involves a rearrangement of the atoms; this is called a chemical reaction.
A chemical reaction is represented by a chemical equation.
Reactants-to the left of the arrow
Products-to the right of the arrow

4. Label the reactants and products in the below equations.
2Na+Cl22NaCl
2NaCl2Na + Cl2

5. Law of Conservation of Matter
In a chemical reaction, atoms are neither created or destroyed.
The atoms on the left (reactants) must equal (balance) the atoms on the right (products).

6. What is wrong with this equation?
Al2S3 + Cl2 AlCl3 + S

7. Balancing Equations __Al2S3 + __Cl2 __AlCl3 + __S
In order to balance the equation, we have to write numbers in front. Try to balance the previous example by writing numbers in front (coefficients) of each element or compound.
__Al2S3 + __Cl2 __AlCl3 + __S

8. Answer
1_Al2S3 +_3_Cl2_2_AlCl3 + _3_S

9. Physical States
Physical states are represented by abbreviations beside the symbols of a chemical equation.
s solid
l liquid
g gas
aq dissolved in water (aqueous)

10. See if you can translate this chemical equation into a word equation.
K(s) + H2O(l)H2(g) + KOH (aq)

11. Answer
Solid potassium reacts (+) with liquid water to produce () hydrogen gas and (+) aqueous potassium hydroxide