Question

C.Calculate the no of particles in 46 g of sodium atom (Atom masses:He =4u,N=14,Na=23) Class 9​

Answer 1

Given:

• Atomic mass of Sodium atom = 46 gram
• Molar mass = Mass of substance in moles = 23 u

To find:

• Number of particles = ?

Solution :-

For solving this question, we use the below formula:

$\bigstar \pink{\boxed{\bf{Number \: of \: particles = \dfrac{Given \: mass}{Molar \: mass}\times Avagadro\: Number}}}$

$\Rightarrow \sf{Number \: of \: particles=\dfrac{46}{23}\times (6.022 \times 10^{23})}$

$\Rightarrow \sf{Number \: of \: particles = 2 \times 6.022 \times 10^{23}}$

$\Rightarrow \sf{Number \: of \: particles= (2 \times 6.022) \times 10^{23}}$

$\therefore \bf{\underline{Number \: of \: particles = 12.044 \times 10^{23}}}$

Know more :-

→ The given mass divided by molar mass can also be written as Number of moles

→ Mass of 1 atom of hydrogen was 1.6 × 10⁻²³ which was not feasible. So, the mass of 6.022 × 10²³ atoms of Hydrogen was approximately equal to 1 gram. This is how Avagadro number came into use.