Download Chemical Equations - Santa Susana High School

Chemical Equations
Objectives:
• 1. Explain how a chemical equation describes
what happens in a chemical reaction.
• 2. Explain how a balanced chemical equation
illustrates the law of conservation of matter.
Key Terms:
• Chemical equation, Balanced chemical
equation, Coefficient
Chemical Equations
• A chemical equation is the shorthand used by chemists to
describe a chemical reaction. Just as in math the equation
matches the number and type of reactants with the products.
Atoms to the left of the
arrow
Atoms to the right of the
arrow
g, D
+
Coefficient
Subscript number
Solid
Liquid
Aqueous
Gas
Reactants
Products
yields (forms, produces, makes, ...)
separates individual atoms or compounds
number directly before an atom or compound (multiplies the
entire substance)
number within a compound (multiplies what precedes it)
(s)
(l)
(aq)
(g)
Chemical Equations
• The types and numbers of atoms in the reactants must match the type
and numbers of atoms in the products.
– Must follow the Laws of Conservation of Mass, Matter, & Energy
• When the atoms in the reactants match the products the equation is said
to be balanced.
– to balance an equation you may only change the coefficient
– A chemical equation that is balanced for charge using subscripts but
does not have coefficients is called a skeleton equation
Balancing Chemical Equations
1. AgNO3 + H2S g Ag2S + HNO3
2. Zn(OH)2 + H3PO4 g Zn3(PO4)2 + H2O
3. hydrogen + sulfur yields hydrogen sulfide (hint:
Remember your diatomic molecules)
4. iron (III) chloride + calcium hydroxide yields iron
(III) hydroxide + calcium chloride
• Balance the top equations by only changing the
coefficients
1. 2AgNO3 + H2S g Ag2S + 2HNO3
2. 3Zn(OH)2 + 2H3PO4 g Zn3(PO4)2 + 6H2O
3. H2 + S g H2S
4. 2FeCl3 + 3Ca(OH)2 g 2Fe(OH)3 + 3CaCl2
• When you count the number and types of atoms
on each side of the equation they should match