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Chemical
equations
Francine
Taylor-Campbell, Contributor
We
will pause and consider the topic
of chemical equations - writing and
balancing them. First, an equation
is a representation of a reaction.
It should show the reactants and products
taking part in a chemical reaction
and should show in what ratio these
products combine.
In
writing an equation, the first step
is to express it in word form. This
ensures that all reactants and possible
products are accounted for. The second
step is to express the word equation
in symbols. Here, the correct formula
for each reactant and product must
be given. The final step is to check
that the same number of atoms of a
given element or their ions is on
each side. When this is done, the
equation is said to be balanced. State
symbols are also added to the equation.
Now,
let us examine the following questions.
1.
Write an equation for the reaction
between magnesium and water.
WORD
EQUATION:
Water
+ Magnesium ---------------Magnesium
Oxide + Hydrogen
FORMULA:
H2O
(l) + Mg (s) -----------MgO (s) +
H2 (g)
Checking
the number of atoms of each element
on both sides
2
H ------------ 2 H
1
O ------------1 O
1
Mg ----------1 Mg
This
equation is BALANCED
2.
Write an equation for the reaction
between sodium carbonate and hydrochloric
acid.
Sodium
carbonate + Hydrochloric acid ———
Sodium chloride + carbon dioxide +
water
Na2CO3
(s) + HCl (aq) ————-
NaCl + CO2 (g) + H2O (l)
Checking
both sides
2
Na ——————
1 Na
1
C ——————-
1 C
3
O ——————
3 O
1
H ————— 2
H
1
Cl ————- 1 Cl
To
balance this equation, 2 can be placed
before the Na atom to have 2 Na atoms
on both sides.
Na2CO3
(s) + HCl (aq) ————-
2NaCl + CO2 (g) + H2O (l)
This
means we now have 2 Cl on one side
and 1 Cl on the other side. Placing
a 2 before HCl will balance this.
Na2CO3
(s) + 2HCl (aq) ————-
2NaCl + CO2 (g) + H2O (l) Balanced
Now
attempt the following:
1.
Ammonia reacts with oxygen in air
to produce nitrogen and water. Write
a balanced equation for this reaction.
2.
Iron III oxide reacts with carbon
monoxide to produce iron and carbon
dioxide.
3.
Calcium hydroxide and ammonium chloride
reacts to give calcium chloride, water
and ammonia.
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The
Herbert Morrison Technical High
School's stage band performs
at the 2009 Heroes Day Civic
and Awards Ceremony at Sam Sharpe
Square in Montego Bay, St James,
on Monday, October 19.
- Christopher Thomas Photo
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Francine
Taylor-Campbell is an independent
contributor. Send questions and comments
to kerry-ann.hepburn@gleanerjm.com
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