Counting Atoms and Balancing Chemical Equations
description
Transcript of Counting Atoms and Balancing Chemical Equations
![Page 1: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/1.jpg)
Counting Atoms and Balancing
Chemical Equations
![Page 2: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/2.jpg)
SubscriptsC12H22O11
There are 12 atoms of CarbonThere are 22 atoms of HydrogenThere are 11 atoms of Oxygen
If there is not a subscript listed, it is understood to be 1.
NaClThere is one atom of SodiumThere is one atom of Chlorine
![Page 3: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/3.jpg)
Learning CheckNaHCO3
Sodium – 1Hydrogen – 1Carbon – 1Oxygen -3
HClHydrogen – 1Chlorine - 1
![Page 4: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/4.jpg)
There are times you will see a compound with parenthesis.
Pb(NO3)2
The 2 after the parenthesis indicates there are two sets of the parenthesis.
Pb(NO3) (NO3)
So, in counting the atoms, you would have the following:
Lead – 1 Oxygen – 6 Nitrogen -2
![Page 5: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/5.jpg)
(NH4)3PO4
Nitrogen – 3Hydrogen – 12Phosphorus – 1Oxygen – 4
Mg(OH)2
Magnesium – 1Oxygen – 2Hydrogen – 2
Learning Check
![Page 6: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/6.jpg)
2H2SO4This means there are 2 compounds of sulfuric acid. Think:
H2SO4 + H2SO4
Counting the atoms:Hydrogen – 4 Sulfur – 2 Oxygen – 8
CoefficientCoefficient
![Page 7: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/7.jpg)
3H3PO4
Hydrogen – 9Phosphorus – 3Oxygen - 12
2H2O
Hydrogen – 4Oxygen - 2
Learning Check
![Page 8: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/8.jpg)
Reading Chemical Equations
The mass of all the reactants (the substances going into a reaction) must equal the mass of the products (the substances
produced by the reaction).
CH4 + 2O2 → CO2 + 2 H2O
Reactants Products
![Page 9: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/9.jpg)
Law of Conservation of Mass
In a chemical reaction, matter cannot be created or destroyed. It
can only be changed.
The reactants MUST contain the same elements and the same
number of each element as the product. They CAN be in different
compounds.
![Page 10: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/10.jpg)
Do the following equations follow the law of conservation of mass?
H2 + O2 H2O
Na + O2 Na2O
Mg + 2HCl MgCl2 + H2
HgO Hg + O2
N2 + 3H2 2NH3
2Na + 2H2O 2NaOH + H2
Zn + 2HCl ZnCl2 + H2
Learning Check
NONO
YESNO
YES
YESYES
![Page 11: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/11.jpg)
Na + O2 → Na2O
For this equation to be balanced, there must be equal amounts of Na in the
reactants and products.
You must add coefficients to balance this equation:
2Na + O2 → Na2O
Balancing Equations
![Page 12: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/12.jpg)
Balancing EquationsTwo ways…
M. I. N. O. H.or
Number charts
![Page 13: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/13.jpg)
Balancing EquationsM. I. N. O. H.
Two ways…
![Page 14: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/14.jpg)
Add coefficients
firstM - Metals
Balance metals such as Fe or Na first.
![Page 15: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/15.jpg)
Add coefficients
firstM - Metals
Balance metals such as Fe or Na first.
Second I - Ions
Looks for polyatomic ions (such as PO4
-3 or SO4-2)
that cross from reactant to product unchanged.
Balance polyatomic ions as a group within its
parentheses.
![Page 16: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/16.jpg)
Add coefficients
firstM - Metals
Balance metals such as Fe or Na first.
Second I - Ions
Looks for polyatomic ions (such as PO4
-3 or SO4-2)
that cross from reactant to product unchanged.
Balance polyatomic ions as a group within its
parentheses.
Third N - Non-metalsChlorine (Cl) or Sulfur (S) are common non-metals
to look for!
![Page 17: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/17.jpg)
Add coefficients
firstM - Metals
Balance metals such as Fe or Na first.
Second I - Ions
Looks for polyatomic ions (such as PO4
-3 or SO4-2)
that cross from reactant to product unchanged.
Balance polyatomic ions as a group within its
parentheses.
Third N - Non-metalsChlorine (Cl) or Sulfur (S) are common non-metals
to look for!
Fourth O - OxygenRemember, oxygen by
itself is O2
![Page 18: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/18.jpg)
Add coefficients
firstM - Metals
Balance metals such as Fe or Na first.
Second I - Ions
Looks for polyatomic ions (such as PO4
-3 or SO4-2)
that cross from reactant to product unchanged.
Balance polyatomic ions as a group within its
parentheses.
Third N - Non-metalsChlorine (Cl) or Sulfur (S) are common non-metals
to look for!
Fourth O - OxygenRemember, oxygen by
itself is O2
Fifth (last) H - HydrogenRemember, hydrogen by
itself is H2
![Page 19: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/19.jpg)
Balancing EquationsTwo ways…
Number charts
![Page 20: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/20.jpg)
Balancing Equations __H2 + __O2 __H2O
O -H -
O -H -
22
12
2
24
2
4
![Page 21: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/21.jpg)
__H2SO4 + __NaOH __H2O +__Na2SO4
Na -SO4 –O –H -
Na -SO4 –O – H -
1113
2112
2
2
24
2
24
Balancing Equations
![Page 22: Counting Atoms and Balancing Chemical Equations](https://reader035.fdocuments.net/reader035/viewer/2022062500/56815754550346895dc4fc65/html5/thumbnails/22.jpg)
__C3H8 + __O2 __CO2 +__H2O
C -O –H –
C -O –H –
328
132
3
37
4
108
5
10
Balancing Equations