Understanding Moles in Chemistry

What is the definition of a mole in terms of particles?

• 15.999 x 10^23 particles

• 1.008 x 10^23 particles

• 6.022 x 10^23 particles

• 9.012 x 10^23 particles

Why is it impractical to count atoms in chemical reactions?

• Atoms are too small to see.

• There are too many atoms to count.

• Atoms do not react in predictable ways.

• Atoms are not stable enough to count.

What is the mass ratio of hydrogen to fluorine in a chemical reaction?

• 1:1

• 1:19

• 2:1

• 19:1

What is the atomic mass of beryllium?

• 12

• 27

• 9

• 16

What is a stoichiometric ratio?

• A ratio of masses that ensures equal number of atoms

• A ratio of pressures that ensures equal force

• A ratio of volumes that ensures equal number of molecules

• A ratio of temperatures that ensures equal energy

Why do atomic masses deviate slightly from whole numbers?

• Because of measurement errors

• Due to changes in temperature

• Because of chemical reactions

• Due to the presence of isotopes and relativity

What is the formal definition of an atomic mass unit?

• 1/12 of the mass of carbon-12

• 1/10 of the mass of hydrogen

• 1/16 of the mass of oxygen

• 1/9 of the mass of beryllium

What is Avogadro's number used for?

• To calculate the speed of light

• To measure the number of atoms in a mole

• To determine the boiling point of water

• To find the density of a substance

How many grams of aluminium are in one mole?

• 9 grams

• 12 grams

• 16 grams

• 27 grams

What is an example of using moles outside of chemistry?

• Determining the age of a tree

• Calculating the height of a building

• Measuring the speed of a car

• Counting sand grains on Earth