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“Chemical Reactions”

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Describing Chemical Reactions

OBJECTIVES:–Describe how to write a word

equation.

–Describe how to write a chemical equation.

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Chemical Reactions_____________________________________

Examples –

H2 + O2 H2O

CH4 + O2 CO2 + H2O

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All chemical reactions… have two parts:

1. Reactants = _______________

2. Products = _______________

The reactants will turn into the products.

Reactants Products

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If it were math… have two parts:

1. Reactants = _______________2. Products = _______________

The reactants will turn into the products.

Reactants Products

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In a chemical reaction A reaction can be described several ways:

1) _______________ a of describing a chemical reaction using the names of the reactants and products e.g.

Iron + sulfur iron (II) sulfide + energy

2) _______________ a of way describing a chemical reaction using the chemical formula of the reactants and products e.g.

Fe + S FeS

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Symbols in equations? the arrow (→) separates the reactants from the

products (arrow points to products)– Read as: “reacts to form” or yields

The plus sign (+) = “and” meaning that they are in contact with each other

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Symbols Con’t_______________

Includes a description of the state of the reactants and products

(s) after the formula = solid: Fe(s)

(g) after the formula = gas: CO2(g)

(l) after the formula = liquid: H2O(l)

(aq) after the formula = dissolved in water, an aqueous solution: NaCl(aq) is a salt water solution

e.g. Zn(s) + CuSO4(aq) ZnSO4(aq) + Cu(s)

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Energy Energy can either be absorbed or

released and is only written in a chemical equation

_______________

e.g. Zn(s) + CuSO4(aq) ZnSO4(aq) + Cu(s) Energy

_______________

e.g. Energy + CuCO3(s) CO2(g) + CuO(s)

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Energy If Energy is absorbed it is taken from

the environment ________

If Energy is released it is sent into the environment ________

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Write a chemical equation for:1. Solid iron (III) sulfide reacts with gaseous

hydrogen chloride to form iron (III) chloride, hydrogen sulfide gas and energy.

_______________

2. Using energy, sodium chloride dissolves in water to form aqueous Sodium and Chloride Ions.

_______________

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Write a sentence for the following then write it as a word equation:

Energy + Fe(s) + O2(g) Fe2O3(s)

_______________

**states are not included in word equations**

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What is a catalyst? A substance that speeds up a

reaction, without being changed or used up by the reaction.

__________are biological or protein catalysts in your body.