Question

Consider the following isotopic abundance data for argon (Ar) and silicon (Si):

Answer 1

Answer:

Explanation:

Molar mass of Argon

= 35.96755 x .00337 + 37.96272 x .00063 + 39.96240 x .99600

= .12121 + .0239165 + 39.80255

= 39.95

Molar mass of silicon

27.97693 x .9223 + 28.97649 x .0467 + 29.97376 x .0310

= 25.803 + 1.35320 + .929

= 28.08

b )

No of atoms of Si  in 78.2 g = 78.2 x 6.02 x 10²³ / 28.08

= 16.76 x 10²³ .

c )

42 Ar / 40 Ar = 1.05006

42 Ar / 39.95 = 1.05006

42Ar = 41.95

2 )

C₁₆H₁₅F₂N₃O₄S

Mol weight = 16 x 12 + 1 x 15 + 2 x 19 + 3 x 14 + 4 x 16 + 32

= 192 + 15 + 38 + 42 + 64+ 32

= 383

No of molecules = .078 x 6.02 x 10²³ / 383

= 1.226 x 10²⁰ molecules .