Question

Number of molecules present in 8g of KNO3 is

Answer 1

mass of kno3 = 39+14+16*4=35+64=98 g
molecules in 98 g kno3= 6.022*10^23
8g =8/98 moles kno3
no. of molecules= 6.022*10^23 * 8/98 = 4.91*10^22

Answer 2

Molar mass of KNO3 = (39+14+3*16)=101 gmol*-1

no of moles of 8 g of KNO3 = (8/101) = 0.0792 mol

1 mole KNO3 contains avogadro no of molecules.

avogadro no is  6.023*10^23

No of molecules present in 8 g of KNO3 = 0.0792 * 6.023*10^23

                                                                   =4.77*10^22

Avogadro's law states that, "at the same temperature and pressure,equal volumes of all gases have the same number of molecules." the volume and amount (moles) of the gas are directly proportional if the temperature and pressure are a constant, for given mass of an ideal gas.This empirical relation can be derived from the kinetic theory of gases under the assumption of a ideal gas.