Chemical Reaction (Signs of Chemrxn and Word Equations).ppt

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1. Chemical Reactions

2. What is a Chemical Reaction?
the processes by which chemicals interact
to form new chemicals with different
compositions
BEFORE
H
2 gas
and
O
2
gas
AFTER
H
2O
liquid

3. Parts of a Chemical Reaction
Reactants  Products
Reactants: Substances that are destroyed by the
chemical change (bonds breakbreak). Its the starting
substances of the reaction.
Products: Substances created by the chemical
change (new bonds formform). Its what you end the
reaction with.
The arrow () is read as “yields”.

4. Other symbols in chemical
reactions
•(s) = solid
•(l) = liquid
•(g) = gas
•(aq) = aqueous solution (the substance is
dissolved in H
2O)
•“+” separates two or more reactants or
products
•“” yield sign separates reactants from
products

5. Evidence for a Chemical Reaction
1) Evolution of light or heat.

6. Evidence for a Chemical Reaction
2) Temperature change (increase or
decrease) to the surroundings.

7. Evidence for a Chemical Reaction
3) Formation of a gas (bubbling or an odor)
other than boiling.

8. Evidence for a Chemical Reaction
4) Color change (due to the formation of a
new substance).

9. Evidence for a Chemical Reaction
5) Formation of a precipitate (a new solid
forms) from the reaction of two aqueous
solutions.

10. Word Equations
•Statements that indicate the reactants and
products in a chemical reaction.
•Ex. Iron (s) + chlorine (g)  iron (III) chloride (s)
•This is read as:
“Solid iron and chlorine gas react (combine) to produce
solid iron (III) chloride”

11. Starter
Lets revise on writing a word equation
Potassium hydroxide and sulfuric acid as
reacted. To form potassium sulfate and
water
write the word equation for the reaction

12. 1)Magnesium reacts with oxygen to form magnesium oxide.
2)Hydrochloric acid reacts with sodium hydroxide to produce sodium
chloride and water.
3)Zinc reacts with sulfuric acid to produce zinc sulfate and hydrogen
gas.
4)Calcium carbonate decomposes to form calcium oxide and carbon
dioxide.
5)Iron reacts with copper (II) sulfate to produce iron (II) sulfate and
copper.