Introduction to Chemical Reactions
A chemical reaction is a process in which one or more substances are converted into new substances that have different physical and chemical properties. When a chemical reaction occurs, the starting materials change, combine or alter themselves into completely new materials. A chemical reaction takes place when an atom can find a more stable way to be joined to other atoms.
In a chemical reaction, those substances present before the reaction are called the reactants. Substances produced in a chemical reaction are called the products.
An example of a chemical reaction would be burning a log. The reactant is a log. The product is the ash and gases produced when burning occurs.
Chemical Equations
Scientists represent chemical reactions in chemical equations. Chemical equations can be in words or in formulas. It is helpful to be able to read it both in words and in equations, so we will be practicing converting from words to equations and vice versa. The most important thing to remember is to complete one set of words at a time, and then move on to the next until finished.
Example:
Solid sodium bicarbonate reacts with aqueous hydrogen chloride to produce aqueous sodium chloride, liquid water and carbon dioxide gas.
In a chemical reaction, those substances present before the reaction are called the reactants. Substances produced in a chemical reaction are called the products.
An example of a chemical reaction would be burning a log. The reactant is a log. The product is the ash and gases produced when burning occurs.
Chemical Equations
Scientists represent chemical reactions in chemical equations. Chemical equations can be in words or in formulas. It is helpful to be able to read it both in words and in equations, so we will be practicing converting from words to equations and vice versa. The most important thing to remember is to complete one set of words at a time, and then move on to the next until finished.
Example:
Solid sodium bicarbonate reacts with aqueous hydrogen chloride to produce aqueous sodium chloride, liquid water and carbon dioxide gas.
Same reaction: NaHCO3 (s) + HCl (aq) --> NaCl (aq) + H2O (l) + CO2 (g)
In writing equations, many times it is important to know the state of the atom or molecule you are working with. To show this, we use the following abbreviations:
(l) - liquid (g) - gaseous (s) - solid (aq) - aqueous
Aqueous means dissolved in water.
(l) - liquid (g) - gaseous (s) - solid (aq) - aqueous
Aqueous means dissolved in water.