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The vapour pressure of ether (mol. mass ...

The vapour pressure of ether (mol. mass = 74) is 60 kPa at 293 K. If 3g of a compound A is dissolved in 50 g of ether at this tempenture, the vapour pressure falls to 56.8 kPa. Calculate molecular mass of A.

Text Solution

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`P^(0) = 60` kPa
P = 56.8 kPa
`W_(2) = 3g `
`W_(1) = ` 50 g
`M_(2) ` = 9
`M_(1) = 74 `
`M_(2) = (W_(2))/(W_(1)) xx M_(1) xx (P^(0))/(P^(0) - P) `
= `(3)/(50) xx 74 xx (60)/(60 - 56.8)`
`M_(2) = 83.25`
`therefore` Molecular mass of A = 83.25.
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