Advertisements
Advertisements
प्रश्न
An aqueous solution of a certain organic compound has a density of 1.063 g mL-1 , osmotic pressure of 12.16 atm at 25 °C and a freezing point of 1.03 °C. What is the molar mass of the compound?
Advertisements
उत्तर
Given: Density of a solution = d = 1.063 g mL-1
Osmotic pressure of solution = π = 12.16 atm
Temperature = T = 25 °C = 298.15 K
Freezing point of solution = Tf = - 1.03 °C
To find: Molar mass of a compound
Formulae: 1. `triangle "T"_"f" = "K"_"f" "m"`
2. π = MRT
3. m = `(1000 "W"_2)/("M"_2 "W"_1)`
Calculation: R = 0.08205 dm3 atm K-1 mol-1
`triangle "T"_"f" = "T"_"f"^0 - "T"_"f"` = 0 °C - (- 1.03 °C) = 1.03 °C = 1.03 K
Kf of water = 1.86 K kg mol–1
Using formula (i),
`triangle "T"_"f" = "K"_"f" "m"`
m = `(triangle "T"_"f")/"K"_"f" = "1.03 K"/(1.86 "K kg mol"^-1)` = 0.554 mol kg-1 = 0.554 m
Using formula (ii),
π = MRT
M = `pi/"RT" = (12.16 "atm")/(0.08205 "dm"^3 "atm K"^-1 "mol"^-1 xx 298.15 "K")` = 0.497 mol dm-3 = 0.497 M
Mass of solvent = `(0. 497 "mol dm"^-3)/(0.554 "mol kg"^-1) xx 1 "dm"^3` = 0.897 kg = 897 g units
Mass of solution = 1.063 g mL-1 × 1000 mL = 1063 g
Mass of solute = 1063 g – 897 g = 166 g
Now, using formula (iii),
m = `(1000 "W"_2)/("M"_2 "W"_1)`
∴ `"M"_2 = (1000 "W"_2)/("m" "W"_1) = (1000 "g kg"^-1 xx 166 "g")/(0.554 "mol kg"^-1 xx 897 "g")`
= 334 g mol-1
The molar mass of the compound is 334 g mol-1.
APPEARS IN
संबंधित प्रश्न
Determine the osmotic pressure of a solution prepared by dissolving 2.5 × 10−2 g of K2SO4 in 2L of water at 25°C, assuming that it is completely dissociated.
(R = 0.0821 L atm K−1 mol−1, Molar mass of K2SO4 = 174 g mol−1)
Which of the following is not a colligative property?
A solution containing 15 g urea (molar mass = 60 g mol–1) per litre of solution in water has the same osmotic pressure (isotonic) as a solution of glucose (molar mass = 180 g mol–1) in water. Calculate the mass of glucose present in one litre of its solution.
At 300 K, 36 g of glucose present in a litre of its solution has an osmotic pressure of 4.98 bar. If the osmotic pressure of the solution is 1.52 bars at the same temperature, what would be its concentration?
Determine the amount of CaCl2 (i = 2.47) dissolved in 2.5 litre of water such that its osmotic pressure is 0.75 atm at 27°C.
Determine the osmotic pressure of a solution prepared by dissolving 25 mg of K2SO4 in 2 liter of water at 25°C, assuming that it is completely dissociated.
Which of the following 0.1 M aqueous solutions will exert the highest osmotic pressure?
Define Semipermeable membrane
Calculate the mass of NaCl (molar mass = 58.5 g mol−1) to be dissolved in 37.2 g of water to lower the freezing point by 2°C, assuming that NaCl undergoes complete dissociation. (Kf for water = 1.86 K kg mol−1)
Calculate the mass of a compound (molar mass = 256 g mol−1) to be dissolved in 75 g of benzene to lower its freezing point by 0.48 K (Kf = 5.12 K kg mol−1).
Define the following term:
Hypotonic solution
Answer the following in one or two sentences.
A solution concentration is expressed in molarity and not in molality while considering osmotic pressure. Why?
Answer the following.
A solvent and its solution containing a nonvolatile solute are separated by a semipermeable membrane. Does the flow of solvent occur in both directions? Comment giving a reason.
Answer the following.
The osmotic pressure of CaCl2 and urea solutions of the same concentration at the same temperature are respectively 0.605 atm and 0.245 atm, calculate van’t Hoff factor for CaCl2.
Answer the following.
Explain reverse osmosis.
Answer the following.
How molar mass of a solute is determined by osmotic pressure measurement?
Which of the following statements is applicable for 0.1 M urea solution and 0.1 M sucrose solution?
What are hypertonic solutions?
Explain the osmotic pressure of a solution with the help of a thistle tube.
Define Osmosis.
Which of the following is a colligative property?
Two solutions have different osmotic pressures. The solution of higher osmotic pressure is called ____________.
At constant temperature the osmotic pressure of a solution is ____________.
A solution containing 10 g per dm3 of urea (molar mass 60 g mol−1) is isotonic with 5% solution of non-volatile solute, MB of solute is:
The temperature at which 10% aqueous solution of (W/V) of glucose will show the osmotic pressure of 16.4 atoms is: (R = 0.082 L atom K−1 mol−1)
Which of the following statements is false?
In isotonic solutions:
(i) Solute and solvent both are same.
(ii) Osmotic pressure is same.
(iii) Solute and solvent may or may not be same.
(iv) Solute is always same solvent may be different.
Give an example of a material used for making semipermeable membrane for carrying out reverse osmosis.
Discuss biological and industrial importance of osmosis.
How can you remove the hard calcium carbonate layer of the egg without damaging its semiprermiable membrane? Can this egg be inserted into a bottle with a narrow neck without distorting its shape? Explain the process involved.
Osmotic pressure of a solution increases if
Isotonic solutions have same
Which one of the following is a colligative property?
Blood cells retain their normal shape in solution which are
Osmotic pressure of a solution containing 2 g dissolved protein per 300 cm3 of solution is 20 mm of Hg at 27°C. The molecular mass of protein is ______.
The following solutions were prepared by dissolving 10 g of glucose (C6H12O6) in 250 ml of water (P1), 10 g of urea (CH4N2O) in 250 ml of water (P2) and 10 g of sucrose (C12H22O11) in 250 ml of water (P3). The right option for the decreasing order of osmotic pressure of these solutions is
Derive an expression to calculate molar mass of non-volatile solute by osmotic pressure measurement.
Assertion (A) : Osmotic pressure is a colligative property.
Reason (R) : Osmotic pressure is proportional to the molality.
Determine the osmotic pressure of a solution prepared by dissolving 2.32 × 10−2 g of K2SO4 in 2L of solution at 25°C assuming that K2SO4 is completely dissociated.
(R = 0.082 L atm K−1 mol, Molar mass K2SO4 = 174 g mol−1)
A solution containing 10 g glucose has osmotic pressure 3.84 atm. If 10 g more glucose is added to the same solution, what will be its osmotic pressure? (Temperature remains constant)
Prove that: M2 = `(W_2RT)/(πV)`.
Name the four colligative properties that are oftently used for determination of molecular mass.
How will you determine molar mass of solute from osmotic pressure?
Write the condition of reverse osmosis.
