Chemical Equation

Terminology in Chemical Equations

• Chemical reactions – one or more chemical changes that occur at the same time, it maybe represented using equations which can be written in words or symbols

• Reactants – pure substances that react in a chemical change

• Products – pure substances formed in a chemical change that has different properties from those of the reactant

Terminology in Chemical Equations

• Symbolic Equations – set of chemical symbols and formula that identify the reactants and products in a chemical reaction

• Word equation – what we learned in 4.2!! • Coefficients – integers are placed in front of the formulas or a

chemical symbol for an element. Is used to determine the ratio between various compounds in a chemical reaction

• State of Matter – letters indicate the compounds’ states– (g) for gas– (l) for liquid– (s) for solid– (aq) for aqueous (dissolved in water)

REACTANTS PRODUCTS Methane + oxygen carbon dioxide + waterWord

equation

Law of Conservation of Mass

• The law by a French chemist Antonie Lavisier• States that mass is conserved in a chemical

reaction• The total mass of products is always EQUAL to

the total mass of reactants in a chemical reaction

Balanced Equations

Shows the identities of each pure substance involved as well as the matching of number of atoms of each

elements on both sides of chemical equations

Skeleton Equation

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Answers

Skeleton Equation

Balanced Equation

3 45

10

3

810

Hints for writing word equations from chemical equations

1) Nearly all elements that use chemical symbols that are not compounds are written as is ex. Cu for copper

2) Memorize Methane, Water, and Ammonia3) Memorize the 7 diatomic elements which are all non-

metals

Example: hydrogen + nitrogen ammoniaSkeleton equation: H2 + N2 NH3

Balanced equation: 3H2 + N2 2NH3

7 Diatomic elements

• Turn to “Strategies for Balancing Equations” on the second last page of chapter 4 notes

• Read through hints for balancing equatinos on page 209 of textbook

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Answers