Q26 of 47 Page 1

a. Predict the main product of the following reactions :

i.


ii.


iii.


b. Give a simple chemical test to distinguish between


c. Why is alpha (α) hydrogen of carbonyl compounds acidic in nature?


OR


a. Write the main product formed when propanal reacts with the following reagents :


i. 2 moles of CH3OH in presence of dry HCl


ii. Dilute NaOH


iii. H2N – NH2 followed by heating with KOH in ethylene glycol


b. Arrange the following compounds in increasing order of their property as indicated :


i. F - CH2COOH, O2N - CH2COOH, CH3COOH, HCOOH - acid character


ii. Acetone, Acetaldehyde, Benzaldehyde, Acetophenone - reactivity towards addition of HCN


a. (i)


(ii)


(iii)


b. Iodoform test is done to distinguish between these two compounds. On adding NaOH / I2 and heat, acetophenone forms yellow ppt. of iodoform(CHI3) whereas benzophenone does not.


c. Alpha (α) hydrogen of carbonyl compounds is acidic in nature due to resonance stabilisation of conjugate base of carbonyl compound


OR


a. (i) When propanal reacts with excess of methanol in the presence of HCl, it forms 1,1-dimethoxy propane.


C2​H5​−CHO+2CH3​OH→C2​H5​−CH(OCH3​)2


(ii) Propanal having α-hydrogen atom undergo aldol condensation in presence of dil. NaOHand forms 3-hydroxy-2-methyl pentanal.


C2​H5​−CHO+ NaOH (dil) →CH3CH2CH (OH) CH (CH3) CHO


(iii) The carbonyl group of propanal is reduced to CH2​ group on treatment with hydrazine followed by heating with KOHin ethylene glycol and the product formed will be propane (CH3CH2CH3)


b.


(i) increasing acid character order is


CH3COOH < HCOOH < FCH2COOH < O2N-CH2COOH


(ii) increasing order of reactivity towards addition of HCN


Acetophenone < Benzaldehyde < acetone < acetaldehyde


More from this chapter

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24

Define the following terms with a suitable example of each :

a. Anomers


b. Essential amino acids


c. Denaturation of protein


 25

a. Define order of reaction. How does order of a reaction differ from molecularity for a complex reaction?

b. A first order reaction is 50% complete in 25 minutes. Calculate the time for 80% completion of the reaction.


OR


a. The decomposition of a hydrocarbon has value of rate constant as 2.5 × 104 s-1 at 27oC. At what temperature would rate constant be7.5 × 104 s-1 if energy of activation is 19.147 × 103 J mol-1?


b. Write a condition under which a bimolecular reaction is kinetically first order. Give an example of such a reaction.
(Given: log 2 = 0.3010, log 3 = 0.4771, log 5 = 0.6990)


 27

a. Account for the following :

i. Manganese shows maximum number of oxidation states in 3d series.


ii. Eo value for Mn3+/Mn2+ couple is much more positive than that for Cr3+/Cr2+.


iii. Ti4+ is colourless whereas V4+ is coloured in an aqueous solution.


b. Write the chemical equations for the preparation of KMnO4 from MnO2. Why does purple colour of acidified permanganate solution decolourise when it oxidises Fe2+ to Fe3+?


OR


a. Write one difference between transition elements and p-block elements with reference to variability of oxidation states.


b. Why do transition metals exhibit higher enthalpies of atomization?


c. Name an element of lanthanoid series which is well known to shown +4 oxidation state. Is it a strong oxidising agent or reducing agent?


d. What is lanthanoid contraction? Write its one consequence.


e. Write the ionic equation showing the oxidation of Fe(II) salt by acidified dichromate solution.


 1

Write IUPAC name of the complex K3[Cr(C2O4)3].

OR


Using IUPAC norms write the formula of Hexaamminecobalt(III) sulphate.