greatest no. of molecules

2009-05-21 9:04 pm

Which of the following gases contain the greatest number of molecules?
(relative atomic masses: H=1.0, C=12.0, O=16.0, Ne=20.2, Cl=35.5)

A. 50.0g of neon
B. 50.0g of oxygen
C. 50.0g of hydrogen chloride
D. 50.0g of carbon monoxide

explain in eng pls
thank you!!

回答 (1)

老爺子

2009-05-21 10:14 pm

✔ 最佳答案

The answer is A.

No. of molecules
= (No. of moles) x (Avogadro constant)
= [Mass / (molar mass)] x (Avogadro constant)
= [50 /(molar mass)] x L
= 50L / (molar mass)

Hence, the smaller the molar mass, the greater is the number of molecules.

Molar mass of Ne = 20.2 g/mol
Molar mass of O2 = 16x2 = 32 g/mol
Molar mass of HCl = 1 + 35.5 = 36.5 g/mol
Molar mass of CO = 12 + 16 = 28 g/mol

Since Ne has the smallest molar mass, thus 50 g of Ne contain the greatest number of molecules.
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