2. Atoms & Elements

A solution is prepared by mixing 2.0 mol of hexane (C6H14) with 3.0 mol of heptane (C7H16), assuming ideal behavior. What is the mole fraction of hexane in the solution?

How many molecules of CH_4 are present in 48.2 g of this compound?

What is the approximate mole fraction of krypton (Kr) in dry air at sea level?

How many atoms of neon are present in 1.30 moles of neon?

How many atoms are present in 1.5 moles of helium (He)?

How many moles of CH3OH are present in 50.0 mL of a 0.400 M CH3OH solution?

How many aluminum atoms are present in 3.78 g of aluminum (Al)? (Atomic mass of Al = 26.98 g/mol)

How many moles of HCl are present in 75.0 mL of 0.150 M HCl solution?

How many moles of SO_2 contain 8.02 × 10^{21} atoms of oxygen?

How many moles of sodium atoms are present in 3.60 × 10^{26} sodium atoms?

How many grams of carbon-12 are present in 1 mole of carbon-12?

How many atoms are present in one mole of gold (Au)?

How many OH⁻ ions are present in 3.00 mol of Ca(OH)₂?

How many atoms are present in 12 grams of carbon-12?

How many hydrogen atoms are present in 5 molecules of water (H_2O)?