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CHEM 120 EXAM 2 REVIEW
30 questions
3-4 worked out problems
Show all work, units, conversion
Practice, practice, practice
Equation sheet provided
Week 3 Concepts
Law of conservation of mass states that mass can not be
gained or lost in a chemical reaction.
Number of atoms of every element on both sides of an
equation must be equal.
Reactants Products
KOH + H3PO4 ---------------------> K3PO4
+ H2O
Fe + H2SO4
-------------------> Fe2
(SO4
)3
+ H2
Mole is a measure that represents Avogadro’s number or 6.022 X 1023 atoms.
A mole of two different substances will not have the same mass.
The periodic table gives us the atomic mass of every element. That atomic
mass is indicated by g/mol (grams/mole). This is also the number of grams
needed to give us 6.022 X 1023 atoms of that element.
To determine the atomic mass of a compound, known as the molar mass, we
would add the atomic masses of all atoms of every element in that compound.
What is the atomic mass of Zn?
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