Answer
(i) 0.568 mol
(ii) $3.42 \times 10^{23} \space molecules$
Work Step by Step
1. Calculate the molar mass of ethanol $\big(C_2H_5OH\big)$:
$C: 12.0 \times 2 = 24.0$
$H: 1.0 \times 6 = 6.0$
$O : 16.0 \times 1 = 16.0$
Molar mass of ethanol = $24.0 + 6.0 + 16.0 = 44.0 \space g/mol$
2. Calculate the amount of $C_2H_5OH$ in moles in 25.0 g of ethanol:
$$25.0 \space g \times \frac{1 \space mol}{44.0 \space g} = 0.568 \space mol$$
3. Find the amount of molecules:
Avogadro's constant: $6.022 \times 10^{23}$
$$0.568 \space mol \times \frac{6.022 \times 10^{23} \space molecules}{1 \space mol} = 3.42 \times 10^{23} \space molecules$$
