Weve done it all counted atoms, examined trends, bonded atoms.
But now, were going to string it all together in a sort of
equation. Like mathbut not math. Remember the conservation of mass?
Matter cannot be created or destroyed.
Slide 3
CHEMICAL EQUATIONS are representations of chemical reactions.
REACTANTS are the chemicals that go into the reaction. These are
listed on the left side of the equation. PRODUCTS are the chemicals
that come out of the reaction. These are listed on the right side
of the equation.
Slide 4
Chemical equations are written much like you would write a math
problem. Youre basically adding things together to make a total on
the right side. But there are some differences, too. Instead of a
=, we use an arrow to show direction ( ). Sometimes equations arent
as simple as adding things up.
Slide 5
Lets look at an example. 2H 2 + O 2 2H 2 O This is the reaction
to form water from its elements. What kinds of terms or features do
you notice in this equation? What are my reactants? What are my
products?
Slide 6
2H 2 + O 2 2H 2 O In the formation of water (H 2 O), we react,
or consume, 2 portions of hydrogen for every 1 portion of oxygen.
As a result, we produce 2 portions of water. Lets look at the atoms
themselves. Is this equation BALANCED? Are all the atoms that start
the reaction present at the end? 4 hydrogen go in, 4 hydrogen come
out 2 oxygen go in, 2 oxygen come out
Slide 7
Try another example: CH 4 + 2O 2 CO 2 + 2H 2 O This is the
reaction for burning methane. Notice that one of the products is
carbon dioxide, a greenhouse gas.
Slide 8
CH 4 + 2O 2 CO 2 + 2H 2 O How many carbons do we start with?
How many do we end with? How many hydrogens do we start with? How
many do we end with? How many oxygens do we start with? How many do
we end with? This equation has already been balanced for you. Lets
see if you can balance one on your own.
Slide 9
___Na + ___H 2 O ___NaOH + ___H 2 This is the reaction for
sodium metal with water. How can you balance this reaction?
Slide 10
Now I will provide an equation that is balanced, but is missing
the products formula. Can you predict the product of this reaction?
C 6 H 12 O 6 + 6 O 2 6 CO 2 + 6 _______
Slide 11
Predict the product Given the reactants, predict the product in
these reactions. 2 Fe + Cl 2 _________ 2 P + 2 O 2 __________ Ca +
S _________ 2 C + 2 H 2 __________ Are these products ionic or
covalent? Can you draw out the product on the fourth example?
Slide 12
Sodium hydroxide (NaOH) is a potent base that draws water and
carbon dioxide out of the air if left in the open. It is also a
base used to neutralize certain acids. ___ NaOH + ___ CO 2 ___ Na 2
CO 3 + ___ H 2 O ___ NaOH + ___ HCl ___ NaCl + ___ H 2 O
Slide 13
Indiana is well known for its limestone, harvested around
Bloomington. Limestone is a hard deposit (mostly calcium carbonate)
that was likely deposited by marine life. Limestone is used in
building, but has stopped being used for monuments in
densely-populated areas. Humans have a large impact on the
environment, with waste producing phenomena like smog and acid
rain.
Slide 14
A reaction for dissolving calcium carbonate is: ___CaCO 3 +
___HCl ___H 2 O + ___CO 2 + ___CaCl 2 Why might limestone be a poor
building material choice for densely-populated cities like Los
Angeles or New York City? Acid rain eats away at the faces of
limestone buildings, eroding the strength of the building. FYI -
The product, calcium chloride (CaCl 2 ), is used as salt for roads
(rock salt) and water hardeners.
Slide 15
Individual/Small group Practice Practice with a partner or
individually on balancing some chemical equations. For each of the
problems, find ALL of the coefficients to balance the equation. Aim
for 10 basic and 6 advanced @ 100 % For extra practice, go for the
mastery problems I know they wont all fit on the worksheet. Just
fill in the first 13, then work on scrap paper. Write down your
problems on the worksheet and turn it in at the end of class.
Slide 16
Basic problems CH 4 + O 2 CO 2 + H 2 OKClO 3 KCl + O 2 H 2 + O
2 H 2 OP 4 + O 2 P 2 O 5 Al + Br 2 AlBr 3 CCl 4 +O 2 CO 2 +Cl 2 C 3
H 8 + O 2 CO 2 + H 2 OSnO 2 + H 2 Sn + H 2 O C 6 H 6 + O 2 CO 2 + H
2 OAgI + Na 2 S Ag 2 S + NaI Advanced problems Na + C 2 Cl 6 NaCl +
C 2 Cl 2 C 2 H 6 + O 2 CO 2 + H 2 O C 2 H 3 Br 3 +O 2 CO 2 +HBrP 4
+ HCl + O 2 PCl 3 + H 2 O AlBr 3 + Cl 2 AlCl 3 + Br 2 C 6 H 5 F+O 2
CO 2 +H 2 O+F 2 CaCN 2 +H 2 O CaCO 3 +NH 3 TiCl 4 + H 2 O TiO 2 +
HCl C 6 O 6 Cr + Cl 2 CrCl 3 + CO Mastery problems AlI 3 + HgCl 2
AlCl 3 + HgI 2 HSiCl 3 + H 2 O H 10 Si 10 O 15 + HCl KOH + H 3 PO 4
K 3 PO 4 + H 2 OBa 3 N 2 + H 2 O Ba(OH) 2 + NH 3 Ca(OH) 2 + H 3 PO
4 Ca 3 (PO 4 ) 2 + H 2 ONH 3 + CO CH 4 + N 2 + O 2 AgNO 3 + K 3 PO
4 Ag 3 PO 4 + KNO 3 C 7 H 9 + HNO 3 C 7 H 6 (NO 2 ) 3 + H 2 O