Question

Question 1.32 Use the data given in the following table to calculate the molar mass of naturally occurring argon isotopes:


Isotope Isotopic molar mass Abundance


36Ar 35.96755 gmol–1 0.337%


38Ar 37.96272 gmol–1 0.063%


40Ar 39.9624 gmol–1 99.600%

Class XI Some Basic Concepts of Chemistry Page 25

Answer 1

we know,
average molar mass of any substance = sum of products of isotopic molar mass and abundance .

∴ average molar mass of Ar = (35.96755 g/mol × 0.337%) + (37.96272 g/mol × 0.063% ) + (39.9624 g/mol × 99.600% )

= (0.00337 × 37.96755) g/mol + (0.00063 × 37.96272) g/mol + ( 0.99600 × 39.9624) g/mol

= (0.121 + 0.024 + 39.803 ) g/mol
= 39.948 g/mol

Answer 2

Answer:

39.826

EXPLANATION