Question

Calculate the number of moles of oxygen molecules in 64 grams of oxygen ( hint:atomic mass of an oxygen atom is 16 unit)

Answer 1

We have,

Mass of oxygen = 64 g

Atomic mass of oxygen molecule = 16 u × 2 = 32u (since it is diatomic)

We know,

Number of moles = (Given mass)/(Molar mass)

⇒ No. of moles = (64 g)/(32 g) = 2 mol

More:-

• 1 u = 1/12th of an atom of Carbon - 12 isotope.
• N_A = 6.022 × 10²³
• Scientific notation is a form of writting very large as well as very small number. It is written in the form of "k × 10ⁿ" where,

1. 1 < k < 10.
2. Remember that the power of 10 is known as "order of magnitude".