Calculate the number of electrons transferred in producing 1.4g of CalciumOxide.[C=40;O=16]
Answers
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Calculations and Chemical Equations
Atomic mass: Mass of an atom of an element, expressed in
atomic mass units
Atomic mass unit (amu): 1.661 x 10-24g
Atomic weight: Average mass of all isotopes of a given
element; listed on the periodic table
Example: Hydrogen atomic weight = 1.008 amu
Carbon atomic weight = 12.001 amu
Carbon atoms are 12 times as massive as hydrogen atoms
Practice: Ca atomic mass = 40.08 amu
Ne atomic mass = 20.18 amu
How many Neon atoms are required to give the same mass
as one calcium atom?
Avogadro’s Number: The Mole
1 Dozen = 12
1 Gross = 144
1 Mole = 6.02 x 1023
1 mole of atoms = 6.022 x 1023 atoms
1 mole of molecules = 6.022 x 1023 molecules
Molar Mass: the mass (in grams) of one mole a
particular substance
There is a unique relationship between molar mass and
atomic weight:
Oxygen’s atomic weight is 16.00 amu.
1 mole of oxygen is 6.02 x 1023 atoms of oxygen
1 amu = 1.661 x 10-24g
What is the molar mass (g/mole) of oxygen?
16.00 amu/oxygen atom x 1.661 x 10-24g/amu
= 2.657 x 10-24 g/atom x 6.02 x 1023 atoms/mole
=16.00 g/mole
Molar mass (in grams) is always equal to the atomic weight
of the atom!
Molar mass (in grams) is always equal to the atomic weight of the
atom!
Examples: Atomic weight of carbon is 12.01amu
Molar mass of carbon is 12.01 g/mol
Atomic weight of helium is 4.00 amu
Molar mass of helium is 4.00 g/mol
Mole (mol): The number of particles (atoms or molecules) in a
sample of element or compound with a mass in grams equal to the
atomic (or molecular) weight
Example: Atomic weight of sodium = 22.99
22.99 g of sodium contains 1 mole
(6.02 x 1023) of atoms
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