How many molecules of N2O5 are there in 175 grams of N2O5?

9.76 x 10²³molecules

Explanation:

Given parameters:

Mass of N₂O₅  = 175gram

Unknown:

Number of molecules  = ?

Solution:

To find the number of molecules contained in the given mass, we need to find the number of moles of N₂O₅ first.

   Number of moles  =

 Molar mass of N₂O₅ = 2(14) + 5(16) = 108g/mol

  Number of moles =   = 1.62moles

  Now;

               1 mole of a substance  = 6.02 x 10²³ molecules

              1.62 mole of N₂O₅  = 1.62 x 6.02 x 10²³  = 9.76 x 10²³molecules

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3