7. Which of the following aqueous solutions has the lowest vapor pressure? a) 1.
ID: 922124 • Letter: 7
Question
7. Which of the following aqueous solutions has the lowest vapor pressure?
a) 1.0m Na2SO4 b) 2.0m glucose(C6H12O6) c) 1.0m (NH4)3PO4 d) 1.5 mCaCl2 e) 2.0 mNaCl
8. Calculate the molar mass of Novocain.
9. Predict the product formed in the following reaction. CH3CH2CH2OH + CH3COOH ->
a) ketone b) aldehyde c) ether d) ester e) carboxylic acid
NOTE: You must be able to draw the structure of the product formed.
7. Which of the following aqueous solutions has the lowest vapor pressure? a) 1.0 m NazSO4 b) 2.0 m glucose (CfH1205) c) 1.0 m (NH43PO4 d) 1.5 m CaClk e) 2.0 m NaCl 8. Calculate the molar mass of Novocain. O HN OCH2CH2 NCHCH3 32 a) 236 g/molb207 g/mol c) 232 g/mol d) 160 g/mol 9. Predict the product formed in the following reaction. CH3CH CH2OH + CH3COOH – a) ketone b) aldehyde c) ether d) ester e) carboxylic acid NOTE: You must be able to draw the structure of the product formed.Explanation / Answer
7) Ans: d
Colligative property is dependent on no of solute particles i.e. no of ions/species.
Species with highest value of (molality x no of ions/species) has highest Relative lowering of vapor pressure which in turn has lowest vapor pressure. ( Relative lowering of vapor pressure is a colligative property )
a) 1.0 m Na2SO4
= 1.0 x 3 [ Na2SO4 = 2 Na+ + SO4-2 = 3 ions]
= 3
b) 2.0 m Glucose
= 2.0 x 1 [ Glucose is a non-electrolyte ]
= 2.0
c) 1.0 m (NH4)3PO4
= 1.0 x 4 [(NH4)3PO4 = 3NH4+ + PO4-3 = 4 ions]
= 4.0
d) 1.5 m CaCl2
= 1.5 x 3 [CaCl2 = Ca2+ + 2Cl- = 3 ions ]
= 4.5
e) 2.0 m NaCl
= 2.0 x 2 [NaCl = Na+ + Cl- =2 ions]
= 4.0
Therefore, 1.5 m CaCl2 has highest Relative lowering of vapor pressure which in turn has lowest vapor pressure.
Hence, 1.5 m CaCl2 has lowest vapor pressure.
8) Ans : a
Novocanin = 13 C + 20 H + 2 O + 2 N
= 13 x 12 g/mol + 20 x 1 g/mol + 2 x16 g/mol + 2 x 14 g/mol
= 156 + 20 + 32 + 28 g/mol
= 236 g/mol
Therefore, molar mass of Novocanin = 236 g/mol
9) Ans: d
Reaction betwen alcohol and carboxylic acid produces ester.
CH3CH2CH2OH + CH3COOH --------> CH3COOCH2CH2CH3
alcohol carboxylic acid ester
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