Question

Calculate the mass of 12.044×10^25 molecule of oxygen gas

Answer 1

$no \: of \: molecules = 12.044 \times {10}^{25} \\ molecular \: mass \: of \: oxygen \: gas = 2 \times 16 = 32u \\ no \: of \: molecules = \frac{given \: mass}{molecular \: mass} \times avogadro \: no \\ let \: given \: mass \: be \: x \: then \\ \frac{x}{32} \times 6.022 \times {10}^{23} = 12.044 \times {10}^{25} \\ = \frac{x}{32} = \frac{12.044 \times {10}^{25} }{6.022 \times {10}^{23} } \\ = \frac{x}{32} = 2 \times {10}^{2} \\ =x = \frac{2 \times {10}^{2} }{32} \\ = x = \frac{ {10}^{2} }{16} \\ = x = \frac{100}{16} \\ = x = \frac{25}{4} \\ = x = 6.25 \\ therefore \: mass \: of \: given \: no \: of \: molecules \: is \: 6.25 \: grams$