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Mole (mol): the amount of material counting 6.02214 × 1023 particles. The value of the mole is equal to the number of atoms in exactly 12 grams of pure.
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The value of the mole is equal to the number of atoms in exactly 12 grams of pure carbon-12. 12.00 g C-12 = 1 mol C-12 atoms = 6.022 × 10 23 atoms The number of particles in 1 mole is called Avogadro’s Number (6.0221421 x 10^23 ).
23
or
23
Converting between Number of Moles and Number of Atoms
Calculate the number of atoms in 2. mol of copper.
A silver ring contains 1.1 x 10^22 silver atoms. How many moles of silver are in the ring?
2.45 mol Cu ×
6.022 ×10 23 atoms 1 mol = 1.48 × 10^24 atoms Cu
1.1 ×10 22 atoms Ag ×
1 mol 6.022 ×10 23 atoms = 1.8 × 10-2^ mol Ag
An element’s molar mass in g/mol is numerically equal to the element’s atomic mass in amu.
or
Converting between Mass and Number of Moles Converting between Mass and Number of Atoms
Calculate the moles of carbon in 0.0265 g of pencil lead.
How many aluminum atoms are in a can weighing 16.2 g?
0.0265 g C ×
1 mol C 12.01 g C
= 2.21 × 10-3^ mol C
16.2 g Al ×
1 mol Al 26.98 g Al
6.022 ×10 23 atoms 1 mol
= 3.62 × 10^23 atoms Al
mol Cu Atoms
g Al mol Al atoms Al
Atoms Ag mol Ag
g C mol C
(a) 3.75 moles of silver (b) 2.36 moles of xenon (c) 158 kg of phosphorus
(a) 449 g of potassium (b) 11.8 g of Ar
(c) 2.16 x 10 24 atoms of lead
(a) 1.9 x 10
24 atoms of Pb (in g)
(b) 4.87 x 10
25 atoms of Zn (in kg) (c) 2.33 x 10 20 atoms of oxygen (in ng)
Hint: Formula Weight of Ca(NO 3 ) 2 = (AW of Ca) + 2(AW of N) + 6 (AW of O)
References: Tro, Chemistry: A Molecular Approach 2 nd^ ed., Pearson Brown/LeMay/Bursten, Chemistry: The Central Science, 12 th^ ed., Pearson
Answers
(a) 2.26 × 10 1. 24 silver atoms; (b) 1.42 × 10 24 xenon atoms (c) 3.07 × 10 27 phosphorus atoms
(a) 11.5 moles; (b) 0.295 moles Ar; (c) 3.59 moles 2.
(a) ) 6.5 × 10 3. 2 g; (b) 5.29 kg; (c) 6.19 × 10 6 ng
1.51 x 10 4. 24 H atoms 24 2.53 x 10 6.^2 ) 3 Ca(NO 71.1 g 5. atoms;
(atoms, molecules, ions)
molar mass Avogadro’s number