Unit: Chemistry

Lesson 2: Describing Chemical Reactions

Essential Questions:1.) What information does a chemical

equation contain?2.) How is mass conserved during a

chemical reaction?3.) What are three types of chemical

reactions?

R u doin chem hw? IDK the chem symbol for H20. Txt me later. Thx.

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Chemical Equation Information

A way to show a Chemical equation

chemical reaction,

using symbols instead

of words

Formulas

A combination of Chemical formula

symbols that

represent the elements

in a compound

Chemical FormulasThe formula of a compound identifies the elements in the compound and the ratio of their atoms.

Modeling a Chemical EquationLike a skateboard, a chemical equation has a basic structure. How many complete skateboards can be made from the parts pictured?

Structure of an Equation

Reactant + Reactant → Product + Product

Beginning substances Ending Substances

“Reacts to form”

How many reactants do the equations have? How many products do the equations have?

HNO3 + NaHCO3 --> NaNO3 + CO2 + H2O

2 H2 + O2 ---> 2 H2O

Mass and Chemical Reactions

The total mass of the Law of conservation

substances stays the of mass

same before and after

the reaction

Conservation of MassIn a chemical reaction, matter is not created or destroyed. What is the mass of iron sulfide produced by this reaction?

Matter can enter or Open system

escape to the

surroundings

Matter does not Closed system

enter or leave

Balancing Chemical Equations

Textbook pages 176-177

Chemical Reactions

Two or more elements Synthesis

or compounds combine

to make a new substance

Compounds break Decomposition

down into simpler

products

One element replacesReplacement

another element or two

elements in different

compounds trade places

Types of ReactionsWhat is each type of reaction represented?