### 2009 help!

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• #### Message 1.

Posted by U15228749 (U15228749) on Friday, 24th May 2013

how would i do these questions :')

18. Which of the following gas samples has the
same volume as 7 g of carbon monoxide?
(All volumes are measured at the same
temperature and pressure.)
A 1 g of hydrogen
B 3.5 g of nitrogen
C 10 g of argon
D 35 . 5 g of chlorine

19. What volume of oxygen (in litres) would be
required for the complete combustion of a
gaseous mixture containing 1 litre of carbon
monoxide and 3 litres of hydrogen?
(All volumes are measured at the same
temperature and pressure.)
A 1
B 2
C 3
D 4

• #### Message 2

, in reply to message 1.

Posted by MissChemTeacher_Bitesize (U15172316) on Saturday, 25th May 2013

2009 Q18

If you work out the number of moles of carbon monoxide you can work out which gas option would have the same volume. One mole of any gas occupies the same volume.

number of moles of CO = mass / gfm
number of moles of CO = 7 / 28 = 0.25 moles

You need do work out which gas (A-D) contains 0.25 moles. You can do that using n of moles = mass / gfm.
Remember that hydrogen, nitrogen and chlorine are diatomic gases.

A) 1g of H2 = 0.5moles

B) 3.5g of N2 = 0.125moles

C) 10g of Ar = 0.25moles

D) 35.5g of Cl2 = 0.5moles

The answer here would have to be C as it contains 0.25 moles which would occupy the same volume as the 7g of CO.

Hope this makes sense.

Miss_Chem

• #### Message 3

, in reply to message 2.

Posted by MissChemTeacher_Bitesize (U15172316) on Monday, 27th May 2013

Hey!
Miss_Chem

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