Final answer:
To find the number of dinitrogen pentoxide molecules, the molar mass of N₂O₅ is determined and the number of moles of N₂ in 123.46g is calculated. After finding the moles of N₂O₅, this is then multiplied by Avogadro's number to find the molecules. The calculated value does not match the provided options.
Step-by-step explanation:
To calculate the number of molecules of dinitrogen pentoxide in 123.46g of dinitrogen, we first determine the molar mass of dinitrogen pentoxide (N₂O₅). The molar mass is the sum of the atomic masses of the constituent atoms, which gives us (2 x 14.01) + (5 x 16.00) = 108.02 g/mol for N₂O₅.
Next, we calculate the number of moles of N₂ in 123.46g, using the molar mass of dinitrogen (N₂), which is 28.02 g/mol (2 x 14.01). This gives us 123.46g / 28.02 g/mol = 4.405 moles of N₂.
Since the ratio of N₂ to N₂O₅ in the balanced chemical equation for their reaction is 1:1, the number of moles of N₂O₅ will also be 4.405 moles. To find the number of molecules, we multiply by Avogadro's number (6.02 × 10²³ molecules/mol):
4.405 moles × 6.02 × 10²³ molecules/mol = 2.651 × 10²´ molecules.
Looking at the options provided, none of them match the calculated value. There might have been a mistake in the options or in the given question. The correct number of molecules of dinitrogen pentoxide from 123.46g of dinitrogen is 2.651 × 10²´.