Bromoform has a normal has freezing point of `7.734^(@)C` and `K_(f)=14.4^(@)C// m`.a solution of 2.60 g of an unknown substance in 100 g of freezes at `5.43^(@)C`. What is the molecules mass of the unknown substance ?
A
16.25
B
162.5
C
100
D
none of these
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The correct Answer is:
b
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DILUTE SOLUTION
NARENDRA AWASTHI|Exercise Level 1 (Q.62 To Q.91)|1 Videos
A solution of 1.25g of a certain non-volatile substance in 20g of water freezes at 271.94K. Calculate the molecular mass of the solute (K_(f)=1.86" K kg mol"^(-1)) .
The Rast method, one of the older techniques for finding the molecular mass of an unknown, measures the freezing point depression of solution in camphor. Camphor is used because its freezing point is very sensitive to added solution solute (It has highest K_(f)) . A solution of 2.342 g of an unknown substancein 49.88 g of camphor freezes at 441.2 K . If K_(f) for camphor is 40.0 Kg mol^(-1) , calculate the molecular mass of the unknown. Strategy: Find the molality of the solution from the freezing point of the pure camphor, the freezing point of the solution and the value of K_(f) by using the relationship DeltaT_(f)=K_(f)m . From the molality, find the no. of moles of solute in given mass of solvent. Finally find the molar mass (Melting point of pure camphar is 453.0 K)
(a) A solution containing 0.5g of naphithalene in 50g C Cl_(4) yield a boiling point elevation of 0.4K , while a solution of 0.6g of an unknown solute in the same mass of the solvent gives a boiling point elevation of 0.65K . Find the molar mass of the unknown solute. (b) The boiling point of a solution of 0.1g of a substance in 16g of ether was found to be 0.100^(@)C higher that of pure ether. What is the molecular mass of the substance. K_(b) (ether) =2.16K kg "mol"^(-1)
A solution containing 6.8 g of non-ionic solute in 100g of water was found to freeze at -0.93^(@)C . If K_(f) for water is 1.86, the mol. Mass of solute is
The freezing point of a solution containing 4.8 g of a compound in 60 g of benezene is 4.48 ^(@) C what is the molar mass of the compound ? (k_(f)=5.1 Km^(-1) , freezing point of benezene =5.5^(@)C )
A 4% solution of sucrose C_(12)H_(22)O_(11) is isotonic with 3% solution of an unknown organic substance. Calculate the molecular mass of the unknown substance.
(a) Define the following terms : (i) Mole fraction (ii) Ideal solution (b) 15.0 g of an unknown molecular material is dissolved in 450g of water . The resulting solution freezes at -0.34^(@)C . What is the molar mass of the material ? (K_(f) for water = 1.86 K kg mol^(-1))
NARENDRA AWASTHI-DILUTE SOLUTION-Level 3 - Match The Column
