A flask contains a mixture of Ar and Ne gas...?

2009-03-11 2:58 am

A flask contains a mixture of Ar and Ne gas. There are .250 moles of Ne which exerts a pressure of 205mm Hg. If the Ar exerts a pressure of 492mm Hg, then how many grams of Ar is there in the flask?

I got approx. 12g, but it says the answer is 24?
If you could explain that would be excellent!
Also,if there is anyone out there that would like me to prepare for the International Chemistry Olympiad Exam I am taking tomorrow that would be great!

Thank you!

更新1:

I meant to say: help me prepare for the IChO exam :)

回答 (1)

Dr.A

2009-03-11 3:37 pm

✔ 最佳答案

total pressure = 697 mm Hg

492/ 697 = moles Ar / moles Ar + 0.250
let x = moles Ar
697 x = 492 x + 123
x =0.6
mass Ar = 0.6 mol x 40 g/mol= 24 g

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