# AS-level Chemistry question help

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#1
Hello can someone help me with this question? I tried it but I am pretty sure I am getting it wrong...
The question is:
In method 2, a known mass of Y was injected into a heated gas syringe and the volume of vapour was measured.
The results of method 2 are shown.
Mass of Y = 0.250g
Volume of vapour = 92cm3
Temperature of vapour = 110°C
Atmospheric pressure = 1.01 × 10^5 PA
Use this information to determine the molar mass of Y.

In the previous part of that question I had to find out the empirical formula for which I got C5H10O.
0
3 weeks ago
#2
(Original post by labmember04)
Hello can someone help me with this question? I tried it but I am pretty sure I am getting it wrong...
The question is:
In method 2, a known mass of Y was injected into a heated gas syringe and the volume of vapour was measured.
The results of method 2 are shown.
Mass of Y = 0.250g
Volume of vapour = 92cm3
Temperature of vapour = 110°C
Atmospheric pressure = 1.01 × 10^5 PA
Use this information to determine the molar mass of Y.

In the previous part of that question I had to find out the empirical formula for which I got C5H10O.
use the formula PV=nRT to work out the moles, and then use moles=mass/MR to work out the molar mass
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#3
(Original post by Wannabevetnurse)
use the formula PV=nRT to work out the moles, and then use moles=mass/MR to work out the molar mass
I tried that already when I use the formula PV=nRT im getting a large number (n= (1.01x10^5x92) / 8.31x383 = 2919.5) for my moles and even then, they already gave me the mass... so I already have the mass and the moles and the Mr from the previous part of the question in which I stated the formula C5H10O (Mr=86)... So I don't really understand what am I supposed to do...
,
0
3 weeks ago
#4
(Original post by labmember04)
I tried that already when I use the formula PV=nRT im getting a large number (n= (1.01x10^5x92) / 8.31x383 = 2919.5) for my moles and even then, they already gave me the mass... so I already have the mass and the moles and the Mr from the previous part of the question in which I stated the formula C5H10O (Mr=86)... So I don't really understand what am I supposed to do...
,
are they all in the proper units? Volume is meant to be in m3 and temperature in Kelvins.
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#5
(Original post by Wannabevetnurse)
are they all in the proper units? Volume is meant to be in m3 and temperature in Kelvins.
Yeah the temperature should always be in K and the volume in m3 for this formula ):
0
3 weeks ago
#6

The empirical formula is the molecular formula.

(Original post by labmember04)
Yeah the temperature should always be in K and the volume in m3 for this formula ):
0
#7
(Original post by Wannabevetnurse)

The empirical formula is the molecular formula.
Thanks for trying to help me but I don't think it is correct since I still can't complete it.
0
3 weeks ago
#8
(Original post by labmember04)
Thanks for trying to help me but I don't think it is correct since I still can't complete it.
can you attach the question then please
0
3 weeks ago
#9
(Original post by labmember04)
I tried that already when I use the formula PV=nRT im getting a large number (n= (1.01x10^5x92) / 8.31x383 = 2919.5) for my moles and even then, they already gave me the mass... so I already have the mass and the moles and the Mr from the previous part of the question in which I stated the formula C5H10O (Mr=86)... So I don't really understand what am I supposed to do...
,
are you sure you converted the 92cm3 into m3 because here when you’re explaining it you haven’t converted it
0
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