Question

9.7*10^17 atoms of fe weight as much as 1cm^3 og h2 what is the atomic mass​ of iron

Answer 1

cc of H_2=1cm^3=0.001 L

This is the volume of the hydrogen gas at STP.

At STP, Pressure,P = 1 atm

At STP, Temperature,T = 273 K

PV=nRT

1 atm\times 0.001 L=n\times 0.0820 L atm/ mol K\times 273 K

n = 4.4670\times 10^{-5} mol

Mass of 4.4670\times 10^{-5} mol of Hydrogen gas = :

2 g/mol\times 4.4670\times 10^{-5} mol=8.934\times 10^{-5} g

9.7\times 10^{17} atoms of iron weigh as much as 1 cc of H2 at S.T.P.

Mass of 9.7\times 10^{17} atoms of iron =8.934\times 10^{-5} g

Moles of iron =\frac{9.7\times 10^{17}}{6.022\times 10^{23} mol^{-1}}=1.6107\times 10^{-6} mol

Atomic mass of iron: \frac{\text{Mass of given atoms}}{Moles}

:\frac{8.934\times 10^{-5} g}{1.6107\times 10^{-6} mol}=55.49 g/mol

The atomic mass of iron is 55.49 g/mol.