CHEM121 EXAM 3 AND ITS
REVIEWED ANSWERS
How is a chemical reaction balanced?
Same amount of reactants and products, masses equal
How to find mass of formula unit
take mass of each element, multiply element mass by how
many present, add together
How to find molar mass of formula unit
same as mass, just mol not g
What is the emperical formula?
just the elements
what is the molecular formula?
elements and subscripts/number present
what is molarity
the number of moles of solute per liter of solution
is solute or solvent present in larger amounts?
solvent
M=?
n/v
Mol =
number of moles / volume
Dilutions of solutions
n=MxV
Mc x Vc =
Md x Vd
acid-base reaction
a reaction where an acid reacts with a base to produce
water and a salt
, what is a base
OH
what is an acid
H
redox reaction
chemical reactions involving electrons transferred from
reducing agent to oxidizing agent
redox reaction equation
A + B = A+ + B-
A is oxidized
B is reduced
what is an electrolyte
Substances that dissolve in water to yield ions
LEO says GER
loss electrons oxidation, gain electrons reduced
Oxidation number
the positive or negative charge of a monatomic ion, not
formal charge
all elements in their elemental form have a ON of
0
monoatomic ions have an ON of
their charge
Alkali metals in compounds have ON of
+1
alkaline earth metals in compounds have ON of
+2
Halogens have ON of (except when combined with O,
F)
-1
The sum of the ON of each atom must add to ____
the charge on the molecule
REVIEWED ANSWERS
How is a chemical reaction balanced?
Same amount of reactants and products, masses equal
How to find mass of formula unit
take mass of each element, multiply element mass by how
many present, add together
How to find molar mass of formula unit
same as mass, just mol not g
What is the emperical formula?
just the elements
what is the molecular formula?
elements and subscripts/number present
what is molarity
the number of moles of solute per liter of solution
is solute or solvent present in larger amounts?
solvent
M=?
n/v
Mol =
number of moles / volume
Dilutions of solutions
n=MxV
Mc x Vc =
Md x Vd
acid-base reaction
a reaction where an acid reacts with a base to produce
water and a salt
, what is a base
OH
what is an acid
H
redox reaction
chemical reactions involving electrons transferred from
reducing agent to oxidizing agent
redox reaction equation
A + B = A+ + B-
A is oxidized
B is reduced
what is an electrolyte
Substances that dissolve in water to yield ions
LEO says GER
loss electrons oxidation, gain electrons reduced
Oxidation number
the positive or negative charge of a monatomic ion, not
formal charge
all elements in their elemental form have a ON of
0
monoatomic ions have an ON of
their charge
Alkali metals in compounds have ON of
+1
alkaline earth metals in compounds have ON of
+2
Halogens have ON of (except when combined with O,
F)
-1
The sum of the ON of each atom must add to ____
the charge on the molecule
