Home
Class 12
CHEMISTRY
A certain substance A tetramerizes in wa...

A certain substance `A` tetramerizes in water to the extent of `80%`. A solution of `2.5 g` of `A` in `100 g` of water lowers the freezing point by `0.3^(@)C`. The molar mass of `A` is
a.`120` , b.`61` ,c.`60` ,d.`62`

Text Solution

Verified by Experts

d. `alpha=(1-i)/(1-(1/n))`
`0.8=(1-i)/(1-(1/4)) rArr i=0.4`
Given that `4A rarr A_(4)`
Alternate method to calculate (i)
`i=("Number of ions" xxalpha)+(1-alpha)`
`=(1/4xx0.8)+(1-0.8) ` [`alpha=80%` or `0.8`]
`=0.2+0.2=0.4`
`DeltaT=iK_(f)xxm`
`0.3=0.4xx1.86xx(W_(B)xx1000)/(Mw_(B)xxW_(A))`
`0.3=0.4xx1.86xx(2.5xx1000)/(Mw_(B)xx100) rArr Mw_(B)=62`
Promotional Banner

Similar Questions

Explore conceptually related problems

Solute 'X' dimerises in water to the extent of 80 % 2.5 g of 'X' in 100 g of water increases the boiling point by 0.3 .^(@)C . The molar mass of 'X' is [ K_(b=0.52 " K gmol"^(-1))]

A non -volatile solute.'A' tetramerises in water to the extent of 80% .2.5 g of 'A' in 100 g of water .lower the freezing point by 0.3 ""^(@)C .The molar mass of Å in mol 4^(-1) is ( K_(T) For water =1.86 K kg mol^(-1) )

If 10.0 g of a non-electrolyte dissolved in 100 g of water lowers the freezing point of water by 1.86^(@)C , the molar mass of the non-electrolyte is ( K_(f)=1.86 Km^(-1) )

6 grams of a substance 'A' dissolved in 100 g of water freezes at - 0.93^(@)C . The molecular mass of 'A' is ( K_(f)=1.86 Km^(-1) ).