Ncert Solutions Chemistry Class 11th
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Expansion of a gas in vacuum is called free expansion. Calculate the work done and the change in internal energy when 1 litre of ideal gas expands isothermally into vacuum until its total volume is 5 litre?
Expansion of a gas in vacuum is called free expansion. Calculate the work done and the change in internal energy when 1 litre of ideal gas expands isothermally into vacuum until its total volume is 5 litre?
This is a Short Answer Type Questions as classified in NCERT Exemplar
During free expansion, external pressure is zero, so Work done, w = -pextΔV
= -0(5 – 1) = 0
Since the gas is expanding isothermally, therefore, q = 0
ΔU = q + w =0+0=0
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35. What is the enthalpy of formation of the most stable form of an element in its standard state?
35. What is the enthalpy of formation of the most stable form of an element in its standard state?
34. When is bond energy equal to bond dissociation energy?
34. When is bond energy equal to bond dissociation energy?
34. For diatomic molecules e.g. H2, O2, Cl2 etc. both energies are equal.
Upvote 33. Which one is the correct unit for entropy?
(a) KJ mol
(b) JK mol
(c) JK mol-1
(d) KJ mol-1
33. Which one is the correct unit for entropy?
(a) KJ mol
(b) JK mol
(c) JK mol-1
(d) KJ mol-1
3. The enthalpies of all elements in their standard states are:
(i) Unity
(ii) Zero
(iii) < 0
(iv) Different for each element
3. The enthalpies of all elements in their standard states are:
(i) Unity
(ii) Zero
(iii) < 0
(iv) Different for each element
2. For the process to occur under adiabatic conditions, the correct condition is:
(i) ?T= 0
(ii) ?p = 0
(iii) q = 0
(iv) w = 0
2. For the process to occur under adiabatic conditions, the correct condition is:
(i) ?T= 0
(ii) ?p = 0
(iii) q = 0
(iv) w = 0
896 mL vapour of a hydrocarbon ‘A’ having carbon 87.80% and hydrogen 12.19% weighs 3.28g at STP. Hydrogenation of ‘A’ gives 2-methylpentane. Also ‘A’ on hydration in the presence of H2SO4 and HgSO4 gives a ketone ‘B’ having molecular formula C6H12O. The ketone ‘B’ gives a positive iodoform test. Find the structure of ‘A’ and give the reactions involved.
896 mL vapour of a hydrocarbon ‘A’ having carbon 87.80% and hydrogen 12.19% weighs 3.28g at STP. Hydrogenation of ‘A’ gives 2-methylpentane. Also ‘A’ on hydration in the presence of H2SO4 and HgSO4 gives a ketone ‘B’ having molecular formula C6H12O. The ketone ‘B’ gives a positive iodoform test. Find the structure of ‘A’ and give the reactions involved.
This is a long answer type question as classified in NCERT Exemplar
The molar mass of the compound = 3.38 x 22400/896 =831gmol-1
Element | Percentage | At.mass | Relative ratio | the simplest ratio |
C | 87.8% | 12 | 7.31 | 3 |
H | 12.19% | 1 | 12.19 | 5 |
Thus the empirical formula of the compound is C3H5
Molecular formula =n x empirical formula = 831/41 x C3H5 = C6H10
Upvote An alkyl halide C5H11Br (A) reacts with ethanolic KOH to give an alkene ‘B’, which reacts with Br2 to give a compound ‘C’, which on dehydrobromination gives an alkyne ‘D’. On treatment with sodium metal in liquid ammonia one mole of ‘D’ gives one mole of the sodium salt of ‘D’ and half a mole of hydrogen gas. Complete hydrogenation of ‘D’ yields a straight chain alkane. Identify A,B, C and D. Give the reactions invovled.
An alkyl halide C5H11Br (A) reacts with ethanolic KOH to give an alkene ‘B’, which reacts with Br2 to give a compound ‘C’, which on dehydrobromination gives an alkyne ‘D’. On treatment with sodium metal in liquid ammonia one mole of ‘D’ gives one mole of the sodium salt of ‘D’ and half a mole of hydrogen gas. Complete hydrogenation of ‘D’ yields a straight chain alkane. Identify A,B, C and D. Give the reactions invovled.
This is a long answer type question as classified in NCERT Exemplar
Upvote