Question

Calculate the number of particles in each of the following:
a. 72 g of Magnesium atoms.
b. 5 moles of Sodium atoms

Answer 1

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$\large\underline{\underline{\red{\sf Question}}}$

Calculate the number of particles in each of the following:

• (a) 72 g of Magnesium atoms.
• (b) 5 moles of Sodium atoms

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We know that molar mass of

• $\blue{\sf Magnesium\: is\:24g}$
• $\blue{\sf Sodium\:is\:23g.}$

We can calculate number of moles as ,

$\boxed{\red{\bf \blue{\dag}\:\:n(moles)=\dfrac{Given\: weight}{Molecular\:weight}}}$

⇒ n = Given weight / Molecular weight

⇒ n = 72g / 24 g

➳ n = 3 .

Now , we know that one mole contains 6.022 × 10²³ particles . Hence 3 moles will have 3 × 6.022 × 10²³ particles = 18.066 × 10²³ particles .

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Given that number of moles of sodium is 5 . Hence the Number of particles will be 5 × 6.022 × 10²³ particles = 30.11 × 10²³ particles.

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