Lecture 4: Chemical Reactions, Gases, and Organic
Chemistry
1 – Chemical reactions and organic chemistry
A chemical reaction is a process in which one set of substances, known as reactants, is
converted into a new set of substances, referred to as products.
Reactants Products
Equations for chemical reactions
A chemical change occurs when a substance converts into one or more new substances.
A chemical reaction always involves a chemical change because atoms of the reaction
substances form new combinations with new properties
Often, there is visual evidence that a chemical reaction has
taken place
A chemical equation tells us the materials needed and the products formed in a chemical
reaction
Writing a chemical equation
The formulas of the reactants are written left of the arrow, and the formulas of the products
of the right.
The delta sign (△) indicates that heat is used to start the reaction
Each formula is followed by an abbreviation giving the physical state of the substance
,Physical states = s – l – g
Aqueous means that a substance is dissolved in
water
Identifying a balanced chemical equation
In chemical reactions, all atoms are conserved. Atoms cannot be gained, lost, or changed
into other types of atoms.
Every chemical reaction is written as a balanced reaction
Coefficients are in front of the formulas that show the number of molecules present
Law of Conservation of Matter
= matter cannot be created or destroyed during a chemical reaction
Balancing a chemical equation
,Types of reactions
Combination reactions
In a combination reaction, two or more elements or compounds bond to form one product
Decomposition reactions
In a decomposition reaction, a single reactant splits into two or more products
, Single replacement reactions
In a single replacement reaction, an uncombined element takes the place of an element in a
compound
Double replacement reactions
In a double replacement reaction, the positive ions in the reactiong compounds switch
places
Inorganic compounds classification
Acid
= substances that release hydrogen ions (H⁺) when dissolved in water (aqueous solution)
Base
= a substance that produce hydroxide ions (OH⁻) in water
Salt
= an ionic compound that is formed when an acid and a base react together (a reaction
called neutralization)
They are made of a positive ion (cation) and a negative ion (anion).
Types of the double replacement reaction
Chemistry
1 – Chemical reactions and organic chemistry
A chemical reaction is a process in which one set of substances, known as reactants, is
converted into a new set of substances, referred to as products.
Reactants Products
Equations for chemical reactions
A chemical change occurs when a substance converts into one or more new substances.
A chemical reaction always involves a chemical change because atoms of the reaction
substances form new combinations with new properties
Often, there is visual evidence that a chemical reaction has
taken place
A chemical equation tells us the materials needed and the products formed in a chemical
reaction
Writing a chemical equation
The formulas of the reactants are written left of the arrow, and the formulas of the products
of the right.
The delta sign (△) indicates that heat is used to start the reaction
Each formula is followed by an abbreviation giving the physical state of the substance
,Physical states = s – l – g
Aqueous means that a substance is dissolved in
water
Identifying a balanced chemical equation
In chemical reactions, all atoms are conserved. Atoms cannot be gained, lost, or changed
into other types of atoms.
Every chemical reaction is written as a balanced reaction
Coefficients are in front of the formulas that show the number of molecules present
Law of Conservation of Matter
= matter cannot be created or destroyed during a chemical reaction
Balancing a chemical equation
,Types of reactions
Combination reactions
In a combination reaction, two or more elements or compounds bond to form one product
Decomposition reactions
In a decomposition reaction, a single reactant splits into two or more products
, Single replacement reactions
In a single replacement reaction, an uncombined element takes the place of an element in a
compound
Double replacement reactions
In a double replacement reaction, the positive ions in the reactiong compounds switch
places
Inorganic compounds classification
Acid
= substances that release hydrogen ions (H⁺) when dissolved in water (aqueous solution)
Base
= a substance that produce hydroxide ions (OH⁻) in water
Salt
= an ionic compound that is formed when an acid and a base react together (a reaction
called neutralization)
They are made of a positive ion (cation) and a negative ion (anion).
Types of the double replacement reaction
