Name _______________________________ Date ____________ Class Period ________
Molar Mass and Conversion Notes and Worksheet
Notes:
 An
is an atom that has the same number of protons as other atoms of the
same element do but that has a different number of
(and a different atomic mass)
 Because isotopes have the same number of protons and electrons, they generally have similar
chemical properties.
 On the periodic table, the atomic mass displayed is an
of the atomic masses of all of
that elements isotopes.
 It is a
average so the mostly commonly found
have the most
impact on the mass.
 A
is the SI base unit that describes the amount of a substance.

constant is the number of particles in 1 mole of a substance and is equal
to 602213670000000000000000 or 6.022 x 1023.
 The
is the mass in grams of 1 mol of a substance.
 This is equal to the atomic mass of atoms measured in grams rather than amu’s.
 Example: The atomic mass of magnesium is equal to 24.30 amu. The molar mass of
magnesium is equal to 24.30 g.
Questions:
1) What is the mass of one mole of Br atoms?
2) What is the mass of one mole of titanium atoms?
3) What is the molar mass of tin?
4) What is the mass of one mole of chromium atoms?
5) What is the mass of 6.02 x 1023 atoms of arsenic?
6) How many atoms are there in one mole of atoms?
7) What is the mass of one mole of Br2 atoms?
8) What is the mass of one mole of water (H2O)?
9) What is the molar mass of CaCl2?
10) What is the molar mass of K2Cr2O7?
Chemistry Worksheet: Calculations Based on Moles and Molar Mass
Substance
Molar Mass
(atomic mass in
grams)
Number of
Particles
Moles of
Particles
(6.022 x 1023 x # of
moles)
(mass / molar mass)
OR (# of particles /
6.022 x 1023)
As
(Arsenic)
3.5 moles of
arsenic atoms
HCOOH
(formic acid)
Mg3(PO4)2
(magnesium
phosphate)
SO2
(sulfur dioxide)
CH4
(methane)
Mass (grams)
(molar mass x # of
moles)
138 grams of
formic acid
1.2 x 1024
molecules of
magnesium
phosphate
3.0 moles of
sulfur dioxide
molecules
64 grams of
methane