2. Atoms & Elements

You have 10.0 g each of Na, Mg, and Al. Which sample contains the greatest number of atoms?

In the context of the mole concept, how many entities (atoms, molecules, or particles) are present in one mole?

Which one of the following contains the most moles of hydrogen atoms?

How many moles of oxygen gas are present in a balloon containing 20.0 grams of pure oxygen gas (O_2)?

How many atoms are present in 1.50 moles of fluorine gas (F_2)?

How many hydrogen atoms are present in 6.02 × 10^{23} molecules of H_2O?

How many moles of hydrochloric acid (HCl) are present in 500. mL of a 0.300 M solution?

Why is it useful to use moles to measure chemical quantities in chemistry?

How many molecules are present in 2.3 moles of oxygen (O_2)?

How many atoms are present in 5.80 moles of He?

How many moles of water are present in 36 grams of H_2O?

How many moles are present in 29.5 grams of Na (sodium)? (Atomic mass of Na = 23.0 g/mol)

If one penny has a mass of 2.5 g, what is the mass of 1 mole of pennies?

A silver necklace has a mass of 21.6 g. How many moles of silver atoms are present in the necklace? (Atomic mass of Ag = 107.87 g/mol)

How many moles of pyridine (C5H5N) are contained in 3.13 g of pyridine? (Molar mass of C5H5N = 79.10 g/mol)