SECTION SUMMARY
11.1
Describing Chemical Reactions Summary:
A chemical reaction can be concisely represented by a chemical equation. The
substances that undergo a chemical change are the reactants. The new substances
formed in a chemical reaction are the products. In accordance with the law of
conservation of mass, a chemical equation must be balanced. When balancing an
equation, you place coefficients in fro t of reactants and products so that the same
number of atoms of each element are on each side of the equation. An equation must
never be balanced by changing the subscripts in the chemical formula of a substance.
Special symbols are used to show the physical state of a substance in a reaction. The
symbol for a liquid is (l); for a solid, (s); and for a gas (g). A substance dissolved in
water is designated (aq). If a catalyst is used to increase the rate of a chemical
reaction, its formula is written above the arrow.
To write a word equation, write the names of the reactants to the left of the arrow
separated by plus signs; write the names of the products to the right of the arrow, also
separated by plus signs.
To write a skeleton equation, write the formulas for the rattans to the left of the yields
sign and the formulas of the products to the right.
After writing the skeleton equation, use coefficients to balance the equation so that it
obeys the law of conservation of mass.
11.1
Describing Chemical Reactions Vocabulary Terms:
Chemical Equation:
a representation of a chemical reaction; the
formulas of the reactants (on the left) are connected
by an arrow with the formulas of the products (on
the right.)
Skeleton equation:
a chemical equation that does not indicate the
relative amounts of the reactants and products
Catalyst:
substance that speeds up the reaction but is not used
up in the reaction
Coefficient
small whole numbers that are placed in front of the
formulas in an equation in order to balance it
Balanced equation:
a chemical equation in which each side of the
equation has the same number of atoms of each
element and mass is conserved
Reactants:
substances that undergo chemical change
Products:
new substance that is formed in a chemical reaction
The End of the Summary