1.

The densities of graphite and diamond at 298 K are 2.25 and 3.31 gcm^(-3) respectively. If the standard fre energydifference(DeltaG^(@)) is eqal to 1895 J mol^(-1), the pressureat which graphite will be transformed into diamond at298 K is

Answer»

<P>`9.92 xx 10^(8) Pa`
`9.92 xx 10^(7) Pa`
` 9.92xx 10^(6) Pa`
none of these

Solution :`-DeltaG = P DELTAV`
`1895= P [ ((12)/( 2.25)- (12)/( 331))xx 10^(-6) m^(2)]`
Calculate P,
[From thermodynamics , `[ (del[DeltaG])/(delP)]_(T)=DeltaV`
or `( DeltaG _(2)-DeltaG_(1))/( P_(2)-P_(1))= DeltaV`
or`DeltaG_(2)- DeltaG_(1) = (P_(2)= P_(1))DELTAU`
Taking `P_(1)=1` bar`= 10^(5)Pa`, calculate `P_(2)]`


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