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Chapter 11.1: Describing Chemical Reactions

+Quickwrite

Write down everything you already know about chemical reactions.

1:30 minutes

+Writing Chemical Equations

A chemical equation occurs when one more more reactants change into one more more new substances called products.

An arrow in a reaction means yields gives, or reacts to produce.

+EXAMPLE

Write a word equation that describes the following reactions:Acetylene reacts with oxygen to produce carbon dioxide and water.C2H2 + O2 CO2 + H2O

+EXAMPLE

When heated, Mercury (III) Oxide reacts to form mercury and water.

Hg2O Hg + O2

+What is a chemical equation?

A chemical equation is a representation of a chemical reaction; the formulas of the reactants (on the left) are connected by an arrow with the formulas of the products (on the right).

Reactants Products

+Define Skeleton Equation.

A chemical equation that does not indicate the relative amounts of the reactants and products.

Identify the reactant(s) & product(s) in the chemical equation:

Li + Br LiBrReactant(s) = Li and BrProduct = LiBr

+A catalyst

A catalyst is a substance that can be added to speed up the reaction but is not used up in a reaction. It is neither a product or a reactant.

+Table 11.1

Symbol Explanation

+ Used to separate 2 reactants or 2 products

“yields”, separates reactants from products

<--> Used in place of “” for reversible reactions

(s) Reactant or product in solid phase

(l) Reactant or product in liquid phase

(g) Reactant or product in gaseous phase

(aq) Aqueous solution (dissolved in water)

Indicates that heat is supplied to the reaction

A formula written above or below a yield sign indicates its use as a catalyst (in tis example, Sulfuric Acid).

+PLEASE ADD TO THE BOTTOM OF THIS PAGE

“Diatomic Molecule” – Molecules made up of 2 atoms. EXAMPLES YOU NEED TO KNOW:

Oxygen (gas) – O2

Nitrogen (gas) – N2

Hydrogen (gas) – H2

Fluorine (gas) – F2

Chlorine (gas) – Cl2 Iodine (gas) – I2

+On Your Own3 minutes for this

Using the symbols in Table 11.1 on Page 2, write a skeleton equation for the following reactions.Hydrochloric acid reacts with zinc to

produce aqueous zinc (II) chloride and hydrogen gas.

+On Your Own

Using the symbols in Table 11.1 on Page 2, write a skeleton equation for the following reactions.Sulfur burns in oxygen to form sulfur

dioxide

+Balancing Chemical Equations

+Balancing Chemical Equations

EACH SIDE HAS THE SAME NUMBER OF PARTS.

+To write a balanced equation:

First: write the skeleton equation.

Then: use coefficients to balance the equation so that so that it obeys the conservation of mass (mass cannot be created or destroyed).

+Balancing Chemical Equations

+Balancing Chemical Equations

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