Answer the following: Arrange the following aqueous solutions in increasing order of osmotic…
Answer the following:
(a)
Arrange the following aqueous solutions in increasing order of osmotic pressure. Give reasons in support of your answer:
(1) $6\cdot0\text{ g}$ per litre of urea solution (molecular weight of urea $= 60\text{ g mol}^{-1}$)
(2) $72\cdot0\text{ g}$ per litre of glucose solution (molecular weight of glucose $= 180\text{ g mol}^{-1}$)
(3) $5\cdot85\text{ g}$ per litre of sodium chloride solution (molecular weight of sodium chloride $= 58\cdot5\text{ g mol}^{-1}$)
(b)
Calculate the mole fraction ($x$) of ethanol and water if $92\text{ g}$ of ethanol is dissolved in $540\text{ g}$ of water. (Atomic mass of $\text{C}=12$, $\text{O}=16$ and $\text{H}=1$)
(c)
What type of azeotropic mixture will be formed by a solution of chloroform and acetone? Justify your answer based on strength of intermolecular interactions that develops in the solution.
Answer
Answer (a)
AIWritten by AI (gemini) - it can contain mistakes.
Concentrations and effective molarities:
(1) Urea: $\frac{6\cdot0}{60} = 0\cdot1\text{ M}$, $i = 1 \Rightarrow iC = 0\cdot1\text{ M}$
(2) Glucose: $\frac{72\cdot0}{180} = 0\cdot4\text{ M}$, $i = 1 \Rightarrow iC = 0\cdot4\text{ M}$
(3) $\text{NaCl}$: $\frac{5\cdot85}{58\cdot5} = 0\cdot1\text{ M}$, $i = 2 \Rightarrow iC = 0\cdot2\text{ M}$
Increasing order of osmotic pressure: (1) Urea < (3) $\text{NaCl}$ < (2) Glucose.
Reason: Osmotic pressure is a colligative property proportional to the total concentration of particles ($iC$).
Answer (b)
AIWritten by AI (gemini) - it can contain mistakes.
Moles of ethanol $n_{\text{eth}} = \frac{92}{46} = 2\text{ mol}$.
Moles of water $n_{\text{water}} = \frac{540}{18} = 30\text{ mol}$.
Total moles $= 2 + 30 = 32\text{ mol}$.
Mole fraction of ethanol $x_{\text{eth}} = \frac{2}{32} = 0\cdot0625$.
Mole fraction of water $x_{\text{water}} = \frac{30}{32} = 0\cdot9375$.
Final answer: x(ethanol) = 0.0625, x(water) = 0.9375
Final answer: 0.0625, 0.9375
Answer (c)
AIWritten by AI (gemini) - it can contain mistakes.
A solution of chloroform and acetone forms a maximum boiling azeotrope. Justification: Chloroform and acetone form intermolecular hydrogen bonds between the hydrogen of chloroform and the carbonyl oxygen of acetone, so solute-solvent interactions (A-B) are stronger than solute-solute (A-A) or solvent-solvent (B-B) interactions, showing negative deviation from Raoult's law.
From ISC 2027 Specimen Chemistry Paper 1, question 21(ii).