2. Atoms & Elements

How many atoms are present in a 12.0 g sample of lithium (Li)? (Atomic mass of Li = 6.94 g/mol)

What is the mass in grams of one mole of any pure substance called?

A sample contains 1.25 grams of CH_4 and no other substances. What is the mole fraction of O_2 in this sample?

How many argon (Ar) atoms are present in 1.5 × 10^2 g of argon?

A copper sample has a mass of 63.5 g. How many moles of copper are present in the sample? (Atomic mass of Cu = 63.5 g/mol)

A solution has a concentration of 0.025 M HCl. How many moles of H+ are present per liter in this solution? (Use the decimal form of your answer.)

Which statement best explains the purpose of using a mole in the measurement of matter?

How many atoms are present in 14 moles of cadmium (Cd)?

How many moles of oxygen atoms are present in 132.2 g of MgSO_4?

In the mole concept, how many copper atoms are present in $1 \mathrm{mol}$ of copper (Cu)?

How many moles are present in 2.3 grams of phosphorus (P)? (Atomic mass of P = 30.97 g/mol)

How many moles of copper are present in a sample with a mass of 63.546 grams? (Atomic mass of copper = 63.546 g/mol)

Avogadro's law states that at a given temperature and pressure:

What is the mass of sodium metal that contains 4.653 × 10^{19} Na atoms? (Atomic mass of Na = 22.99 g/mol)

How many atoms are present in 0.250 moles of Rb?