unit 8 - Chemical reactions and Stoichiometry quiz

Evidence of Chemical reactions

1. UNexpected color changes

2. Energy changes - gets hot or cold: NO HEAT SOURCE

3. Odor changes(mostly for organic chemistry)

Energy changes

1) Exothermic(out of) - releases energy. 2) Endothermic(in to) - requires energy.

More Evidence of Chemical reactions

4. Precipitate - a solid formed from a mixture of solutions.

5. Gas produced - bubbles with NO heat source.

6. Irreversible process - layer with other evidence, good to look things over.

7. New properties - Characteristics won’t behave like the original.

Symbol of solid in chemical equations

s

Symbol of Liquid in chemical equations

l

Symbol of Gas in chemical equations

g

Symbol of Aqueous in chemical equations

aq (which is dissolved in water).

How many types of reactions are there?

5

Catalyst

a substance or process that speeds up the reaction.

True

There are 5 main examples of catalyst

The 5 main examples

1) compounds. 2) elements. 3) heat. 4) light. 5) aqueous solution(sometimes).

True

When balancing a chemical reaction, use a written inventory of the atoms to compare quantities on each side.

Balancing a chemical reaction

Stay away from atoms in two places on a side. (balance them last).

Balancing a chemical reaction pt. 2

Make odd quantities even on both sides.

Synthesis (Combination) Reactions

Two or more substances react to form a single product.

Decomposition Reactions

A single compound broken into two or more products. Most require energy to occur.

Combustion Reactions

Oxygen reacts with substance to release energy. Some are synthesis reactions.

True

If the coefficient before water is ODD, Double the hydrocarbon and start over.

Single Replacement Reactions

An element replaces one part of a compound. Keep the polyatomic ions together and balance as a unit.

Double Replacement Reactions

Exchange of ions between two compounds. No change in charges, and may end with precipitate. Keep the polyatomic ions together and balance as a unit.