Answer:
4.99*10²³ molecules of N₂O₄ are in 76.3 g of N₂O₄
Explanation:
Avogadro's Number is the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023*10²³ particles per mole. Avogadro's number represents a quantity without an associated physical dimension. Avogadro's number applies to any substance.
You know that the molar mass of N₂O₄ is 92.02 g/mol, and you have 76.3 g. Then you can apply the following rule of three: 92.02 grams are present in 1 mole of the compound, 76.3 grams in how many moles are they?
amount of moles= 0.83 moles
Then, you can apply another rule of three: if by definition of Avogadro's number 1 mole of the compound has 6.023*10²³ molecules, 0.83 moles of the compound, how many molecules will it have?
amount of molecules= 4.99*10²³
<u><em>4.99*10²³ molecules of N₂O₄ are in 76.3 g of N₂O₄</em></u>