Question

Calculate the number of moles.
i) $12.046\times {10}^{23}$ atoms of Copper
ii) $27.95g$ of Iron
iii) $1.51\times {10}^{23}$ molecules of $C{O}_2$

Answer 1

number of moles$=n=\frac{weight}{molecularweight}$

Also, number of molecules $=n\times 6.022\times {10}^{23}$

$1.$ Moles of $Cu=\frac{12.046\times {10}^{23}}{6.023\times {10}^{23}}=2$ $moles$

$2.$ Moles of Iron $=\frac{27.95}{55.9}=0.5$ $moles$

$3.$ Moles of $C{O}_2=\frac{1.51\times {10}^{23}}{6.023\times {10}^{23}}=0.25$ $moles$