Taking into account the definiton of molar mass and Avogadro's number, there are 8.4322×10²¹ molecules N₂O₄ molecules in a 1.25 g sample of dinitrogen tetroxide.
First of all, you should know that the molar mass of dinitrogen tetroxide, that is, the mass of one mole of the compound, is 92.011 [tex]\frac{g}{mole}[/tex]. Then the number of moles that 1.25 grams of the sample contain can be calculated by:
[tex]amount of moles=1.25 gx\frac{1 mole}{92.011 g}[/tex]
Then:
amount of moles= 0.014 moles
On the other hand, Avogadro's Number is called 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 and it applies to any substance.
Then you can apply the following rule of three: if you can define Avogadro's number, 1 mole of the compound contains 6.023×10²³ molecules, 0.014 moles contains how many molecules?
[tex]number of molecules=\frac{0.014 molesx6.023x10^{23} molecules}{1 mole}[/tex]
number of molecules= 8.4322×10²¹
Finally, there are 8.4322×10²¹ molecules N₂O₄ molecules in a 1.25 g sample of dinitrogen tetroxide.
Learn more about Avogadro's Number:
