Unit 9 Chemical Reactions

Step 1 for balancing equations

Write the skeleton equation for the reaction

Step 2 for balancing equations

Count the atoms of each element in reactant

Step 3 for balancing equations

Count atoms of each element in products

Step 4 for balancing equations

Change the coefficients to make the number of atoms of each element equal on both sides of the equations

Step 5 for balancing equations

Make sure coefficients in lowest ratio and verify that the equation is balanced.

Chemical equilibrium

Many chemical reactions are reversible

5 types of chemical reactions

• Synthesis

• Decomposition

• Combustion

• Single replacement

• Double replacement

Synthesis reaction

Two substances (or more) combine to form a new single product

Combustion reactions

Substances reacting with oxygen to release energy as light and heat

Decomposition reactions

Opposition of synthesis reactions. A single, more complex compound break down to form two or more simpler, smaller elements or compounds

Single-replacement reactions

A single element replaces a part of another compound

Double-replacement reactions

An exchange of ions between two ionic compounds

Aqueous solution

A solution in water

Solution

Homogeneous mixtures of solutes and a solvent

Solute

The dissolved substance

Solvent

The substance that does the dissolving

Precipitate

Solid product formed in a reaction and mostly happens in double-replacement ionic reactions in aqueous solutions

Precipitation reaction

A reaction in which a precipitate is formed

Complete ionic equation

Chemical equation written with ions instead of compound formulas

Spectator ions

The ions in a complete ionic equation that do not participate in the reaction and can be removed

Net ionic equation

The final form of a reaction equation showing only the substances involved in the reaction

Result of reactions that form water

The number of solvent particles (water molecules) are increased

Result of gas-forming reactions

The formation of precipitate (solid) or water (liquid)