Question

35
0.1 Chlorine has two isotopes cl & cl with their natural abundance 75% and 25%
17
respectively. What will be the average atomic mass of chlorine.
(a) 35.5
(b) 35.0
(c) 37.0
(d) 36.0​

Answer 1

Answer:

Average atomic mass is given by:

M

av

=

0.75+0.25

35×0.75+37×0.25

=35.5 gm/mol

Answer 2

11th/Chemistry

Mole Concept

Answer :

Natural abudance of Cl³⁵ = 75%

Natural abudance of Cl³⁷ = 25%

We have to find average atomic mass of chlorine$.$

Average or mean atomic mass : Average atomic mass of element is given by

• Aavg = (A₁x₁ + A₂x₂)/(x₁ + x₂)

Here A₁, A₂ are isotopic mass of element ans x₁, x₂ are natural abudance of isotopes.

⭆ Aavg = (A₁x₁ + A₂x₂)/(x₁ + x₂)

⭆ Aavg = [(35×75) + (37×25)]/100

⭆ Aavg = (2625 + 925)/100

⭆ Aavg = 3551/100

⭆ Aavg = 35.5 g/mol

★ Isotopes are the atoms with identical atomic number but different mass number.

• C¹² and C¹⁴
• O¹⁶ and O¹⁸

Cheers!