Question

Calculate the number of moles of oxygen gas present in 64 g of oxygen gas.

Answer 1

Given:

The mass of Oxygen (O) = 64g

To Find:

The number of moles of oxygen

Solution:

We know that the number of moles of a substance in a given sample =  

Here, m = The given mass of the element or compound

         M = The gram molar mass of the given element or compound

Since the Molar Mass of Oxygen = 16g

(Here we have to take the molar mass of O (16g) and not of oxygen molecule O₂ (32g) because we need to find the number of moles of the oxygen atom.)

⇒ The number of moles of oxygen atom =  

= 4

Hence, the number of moles of oxygen atom in 64 grams of sample is 4.

Answer 2

Answer:

64 gram oxygen = 64/16 = 4 mole oxygen. "1 mole of any element contains 6.022 × 1023 atoms."