Question

Calculate the number of CaO molecules in 2.8 g of quicklime.

Answer 1

Given that

Mass of $CaO,W=2.8g$

Moles mass of $CaO,M=56g/mol$

$\therefore$ Number of moles of $CaO,n=\frac{W}{M}=\frac{2.8}{56}mol$

$=0.05moles$

$\therefore$ Number of molecules $,N=n\times N_A$

$=0.05\times 6.022\times {10}^{23}=3.011\times {10}^{22}$ molecules