Chemical Equations. A Quick Review… Chemical symbol: A shorthand notation for an element’s name....
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Transcript of Chemical Equations. A Quick Review… Chemical symbol: A shorthand notation for an element’s name....
A Quick Review…
• Chemical symbol:A shorthand notation for an element’s name.
A shorthand notation for a compound or a molecule.
• Chemical formula:
A Quick Review…
• Chemical reaction:The process by which one or more substances undergo change to produce one or more different substances.
• Writing out a chemical reaction can take a long time and isn’t universal, so there exists a simpler way to represent a chemical reaction called a…
Chemical Equations
• Chemical equation:A shorthand notation of a chemical reaction using chemical formulas and symbols.
• Example:
C + O2 CO2
Parts of a Chemical Equation
C + O2 CO2
Reactants: the starting materials in a chemical reaction. (LEFT) - Written before the arrow.
Products: the substances formed in a reaction. (RIGHT) - Written after the arrow.
Parts of a Chemical Equation
C + O2 CO2
Plus sign: reads: ‘reacts with’.Carbon reacts with dioxide
Arrow: Reads ‘to produce’ or ‘to yield’
Carbon reacts with dioxide to yield Carbon dioxide.
Why We Counted Atoms
C + O2 CO2
The number of atoms we start with (reactants side) must equal the number of atoms we end up with (products side).
All equations must be balanced. The number of atoms of each element in a reactant must equal the number of the same elements in the product.
Reactants = Products
Why We Counted Atoms
C + O2
When counting atoms for each side, think of the yield sign as an equal sign.
C + O2 O2=• The number of Carbon in the reactants must equal the number of Carbon in the product.
• The number of Oxygen in the reactants must equal the number of Oxygen in the product.
C
O2C
Balancing the Equation
C +
O
O2C
•Count the number of atoms of each element on the reactants side using symbols to represent the number of atoms.
C
O2
O
• Are all atoms counted for on the left side? If so, we can move to the right side of the arrow.
Balancing the Equation
C +
O
O2C
• Repeat the same process for the right side as you did with the left side.
C
O2
OOCO
Balancing the Equation
C +
O
O2C
• Start with Carbon and count each side.
C
O2
OOCO
1 1
• Do we have an equal amounts of Carbon?
Let’s move on to Oxygen
Balancing the Equation
C +
O
O2C
• Now Count the Oxygen on each side.
C
O2
OOCO
2
• Do we have an equal amounts of Oxygen?
We have a BALANCED equation.
2
Balancing Example
H2 + O2 OH2
HH
OO
•Count the number of atoms of each element on the reactants side using symbols to represent the number of atoms.
Balancing Example
H2 + O2 OH2
HH
OO
• Repeat the same process for the right side as you did with the left side.
HH
O
Balancing Example
H2 + O2 OH2
HH
OO
HH
O
• Start with Hydrogen and count each side.• Do we have an equal amounts of Hydrogen?
22
Balancing Example
H2 + O2 OH2
HH
OO
HH
O
• Now count Oxygen on each side.• Do we have equal amounts of Oxygen?
2 1
Balancing Example
H 2+ O 2
OH 2
• We cannot leave an equation unbalanced. What can be done to fix it?
Balancing Example
H2 + O2 OH2
HH
OO
HH
O
• Are Oxygen atoms equal on both sides?
HH O
• Are Hydrogen atoms equal on both sides?
Let’s try and fix Hydrogen.
HH
Balancing Example
H2 + O2 OH2
HH
OO
HH
O
• The number of boxes represents the coefficient.
HH O
• What is the coefficient in front of H2?
HH
• What is the coefficient in front of H2O?
2 21
Practice
H2 + Cl2 ClH
HH
ClCl
HClClH
211
Dihydrogen reacts with dichloride to yield Hydrogen monocholoride.
Practice
N2 + H2 H3N
NN
HH
NHHHNHHH
HH
HH
3 21
Dinitrogen reacts with dihydrideto yield Nitrogen trihydride.