Phase 3

How are chemical reactions represented

By chemical equations

What does the + sign mean in a chemical equation

"Reacts with"

What does the arrow mean in a chemical equation

"Produces"

Reactants

(Starting substances)
The chemical formulas to the left of the arrow

Products

The chemical formulas to the right of the arrow, represent substances produced in the reaction

Coefficients

The number in front of the formula, indicate the relative numbers of molecules of each kind involved in the reaction

Balancing equations

Determining the coefficients that provide equal numbers of each type of atom of both sides of the equation

Coefficients should be...

The smallest whole-number possible (can also be fractions or decimals)

What does (g) mean

Gas

What does (s) mean

Solid

What does (l) mean

Liquid

What does (aq) mean

Aqueous solution

Types of reaction

- combination reaction
- decomposition reactions
- combustion reaction

Combination reactions

Two or more substances react to form one produc. A reaction of this type between a metal and a non metal produces an ionic solid

Decomposition reactions

One substances undergoes a reaction to produce two or more substances

Combustion reaction

Rapid reactions that produce a flame (most of them have O₂ from air as a reactant)

Hydrocarbons combustion in air react with O₂ to form..

CO₂ and H₂O

Single replacement reaction

Is a reaction in which one element replaces a similar element in a compound
-metal replaces metal
-non-metal replaces non-metal

Double-replacement reactions

Is a reaction in which the positive and negative ions of two atomic compounds exchange places to form to new compounds
-cations replace cations
-anions replace anions

Neutralization

An acid and a base react to form water and salt, and involves the combination of H⁺ ions and OH⁻ to generate water

Neutralization of a strong acid and strong base...

Has a pH that equals to 7

Neutralization os a strong acid and a weak base...

Has a pH of less than 7

Neutralization of a strong base and weak acid...

Has a pH greater than 7