Question

A sample of ethane has the same mass as 10 million molecules of methane. How
many ethane molecules does the sample contain













A sample of ethane has the mass as 10

Answer 1

Molar mass of methane = 16 g/mol
1 mole of methane contains = 6.023 x 1023 molecules
Mass of 6.023 x 1023 molecules of methane = 16 g
​Mass of 1 molecule of methane = 16/ (6.023 x 1023 ) g

Mass of 10 million molecules or 10 x 106 molecules = [​16/ (6.023 x 1023 ) ] x 107 = 2.65 x 10-16 g

Thus mass of ethane sample = ​ 2.65 x 10-16 g

​Molar mass of ethane or mass of 1 mole of ethane = 30 g/mol

If 30 g of ethane contain = 6.023 x 1023 molecules
Then

​ 2.65 x 10-16 g of ethane contains = [6.023 x 1023 /30] x 2.65 x 10-16 = 5.3203 x 106 molecules of ethane

Answer 2

Answer:

5.33 × 10⁶

see image for solution.

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