Determine the mass of 9.2 x 10^18 molecules of dinitrogen tetroxide.

Answer: 1.4x10-3 g N2O4

Explanation: First convert molecules of N2O4 to moles using Avogadro's Number. Then convert moles to mass using the molar mass of N2O4.

9.2x10^18 molecules N2O4 x 1 mole N2O4 / 6.022x10²³ molecules N2O4

= 1.53x10-5 moles N2O4

1.53x10-5 moles N2O4 x 92 g N2O4 / 1 mole N2O4

= 1.4x10-3 g N2O4