Chemistry Unit 4 Test review

What is a chemical reaction?

It is a process by which one or more substances are rearranged to form different substances

Evidence of chemical reactions include:

change in temperature, color, odor, formation of gas bubbles and a solid is formed

precipitate

when 2 liquids are mixed and form a solid

What is a reactant

Starting substances of the chemical equation

Products

substances formed in the reaction

What is a chemical equation?

a statement that uses chemical formulas to show the identities and relative amounts of the substances involved in a chemical reaction

What is the rate of a chemical reactions

the speed which the reaction happens

What affects the rate of a reaction?

Temperature of reactants, size of the reactants, agitaton/stirring, concentration of reactants

What is a catalyst

a substance that changes the rate of a chemical reactions without being consumed or changed significantly

What is an exothermic reaction?

A chemical reaction in which heat is released to the surroundings

What is an endothermic reaction?

A chemical reaction that requires heat (it takes in heat or becomes cold)

What is the most fundamental law of chemistry?

The law of conservation of mass which states that the matter and mass of a system must remain constant over time since the system’s mass can’t be changed so quantity can neither be added or removed

What is a synthesis reaction?

two or more substances coming together to make one compound (A+B—>AB)

What is a decomposition reaction?

one compound breaking down into two or more substances (AB—>A+B)

Single Displacement

a single element replaces a second element in a compound (A+BC—> B+AC)

Double Displacement

the exchange of positive ions between two compounds (AB+BC—>AC+BA)

Acid-Base or Neutralization

an acid and base reacting to form a salt and water

Combustion

reaction of an element or compound with oxygen to produce water and carbon dioxide

How do you predict a synthesis reaction?

You combine two elements into a compound using the “criss-cross” rule and don’t carry over the subscripts

Decomposition Rule 1:

A metal carbonate will decompose into a metal oxide and carbon dioxide (K2CO3—>K2O+CO2)

Decomposition Rule 2:

A metal chlorate will decompose into a metal chloride and oxygen (Zn(ClO3)2—>ZnCL2+3O2)

Decomposition Rule 3:

A metal hydroxide will decompose into a metal oxide and water (2LiOH—>Li2O+H2O)

Decomposition Rule 4:

A metal oxide will decompose into a metal and oxygen (2CaO—>2Ca+O2)

Single Displacement prediction

USE Activity Series chart (when a single element is a metal, it will replace the metal and if it is a nonmetal, it will replace the nonmetal)

Double Displacement prediction

swap the two metals and balance