The Mole, Molar Mass, and Avogadro's Number

How does one get the mass of one mole of any element?

• Look up the average atomic mass from the periodic table

• Look up the atomic number from the periodic table

• Look up the number of neutrons of an atom

• Count Avogadro's Number of atoms and then put them on a balance

What is Avogadro's Number?

• 6.023 x 10²³

• 6.023 x 10^-23

• 6.023

• 6.023 x 10¹⁰⁰

Albert Einstein found that his gold cap from his dental filling had a mass of 0.0550 grams. How many atoms are there in that filling? The atomic mass of Au is 196.967 amu.

• 2.79 x 10^-4

• 3851

• 0.055

• 1.68 x 10²⁰

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If there are 1.4 billion people in China, how many moles of people does that number represent?

• 2.32 x 10^-15

• 1.08 x 10¹⁶

• 6.023 x 10²³

• 1.66 x 10^-24

What is the mass of 5.000 moles of potassium with an average atomic mass of 39.0983 amu?

• 195.5 g

• 0.005115 g

• 196 g

• 200 g

What is the mass of 2.589 x 10²² atoms of uranium. Average atomic mass of U is 238.0289 amu.

• 10.23 g

• 0.04299 g

• 0.09769 g

• 238.0289 g

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To change mass to atoms, how many conversion factors would need to be used?

• 2

• 3

• 1

• 5

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NGSS.HS-PS1-7

To convert moles to mass one would

• multiply moles given by the molar mass in grams

• divide the moles given by the molar mass in grams

• simply use the molar mass for the given substance

• multiply the average atomic mass by the molar mass

What is the mass of 1 atom of uranium to 5 significant figures; its atomic number is 92.

• 238.03 amu

• 238.03 g

• 238.03 kg

• 238.05

A rubidium atom has an average atomic mass of 85.47 amu. How is that average attained?

• the weighted average of all known isotopes is used to determine the average atomic mass

• there are many isotopes of rubidium with different atomic numbers

• each rubidium isotope has different numbers of electrons

• when the average atomic mass is calculated one can only use masses that are determined to 5 significant figures