A chemical equation is a short hand expression of a chemical
reaction. There are two parts to a chemical equation. The reactants
are the elements or compounds on the left
side of the arrow (-->). The elements and compounds to the right
of the arrow are the products.
Identify the reactants and the products in the equation below.
Reactants: 2 H2
+ O2
Products: 2H2O
Look at the equation above. Notice the two purple
2s. These numbers are called coefficients.
Coefficients are used to balance chemical equations.
The blue arrow is
a yield sign. It separates the reactants
form the products. Most yield signs will be like the one above, but there
are some other yield signs you need to know.
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A formula written above a yield sign indicates it is a catalyst
used to speed up a reaction. |
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A triangle above the yield sign indicates the reaction is heated. |
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Two half arrows pointing in opposite directions indicates that this
is a reversible reaction. |
The following symbols are written in parenthesis
after a formula and represent the state of the element or compound.
s |
solid |
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solid precipitate is produced (used
for products only, not reactants) |
cr |
crystalline (used
for solid ionic compounds) |
l |
liquid |
aq |
aqueous (substance is
dissolved in water) |
g |
gas |
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gas is produced
(used for products only, not reactants) |
Identify the following about the equation below: the reactants,
the products, the coefficients used, the state of each element or compound.
Reactants: 2 Na (s)
+ 2H2O (l)
Products: 2 NaOH (aq) + H2
Coefficients: 2,2,2
State:
Na - solid, H2O -
liquid, NaOH - aqueous, H2 - gas
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