Question

Calculate the number of partricles in each of the following .

(a) 46 g of Na atoms ( number from mass )
(b) 8 g O2 molecules ( number of molecules from mass )

Answer 1

Answer:

The given mass of sodium is 46g. ∴ The number of particles present in 46g of Na atom is 12.046×1023. Given data contains 8gO2 molecules (number of the molecules form the mass). ... Given data contains 0.1 mole of carbon atom (number form gives moles).

Answer 2

☘️ Solution :

(a) The number of atoms

$= \sf \: \dfrac{ \: given \: \: mass \: }{ \:molar \: \: mass} \times Avogadro \: \: number \\ \\ \sf \: ⟹ N \: = \: \frac{m}{M} \times N \: _0 \\ \\ \sf \: ⟹N \: = \: \frac{46}{23} \times 6.022 \times 10 {}^{23 } \\ \\ \sf \: ⟹N \: = \: 12.044 \times 10 {}^{23}$

(b) The number of molecules

$= \sf \: \dfrac{ \: given \: \: mass \: }{ \:molar \: \: mass} \times Avogadro \: \: number \\ \\ \sf \: ⟹ N \: = \: \frac{m}{M} \times N \: _0$

atomic mass of oxygen = 16 u

$\therefore$ molar mass of $\sf O_2$ molecules

= 16 × 2 = 32g

$⟹ \sf \:N~=~ \dfrac{8}{32} \times 6.022 \times 10 {}^{23} \\ \\⟹ \sf \:N~=~ 1.5055×10²³\\ \\ \sf = 1.51 \times 10 {}^{23}$