Explain why alkyl groups act as electron donors when attached to a π system.
When an alkyl group is attached to a π system, it acts as an electron-donor group by the process of hyperconjugation. To understand this concept better, let us take the example of propene.
In hyperconjugation, the sigma electrons of the C-H bond of an alkyl group are delocalised. This group is directly attached to an atom of an unsaturated system. The delocalisation occurs because of a partial overlap of a sp3-ssigma bond orbital with an empty p orbital of the π bond of an adjacent carbon atom.
The process of hyperconjugation in propene is shown as follows:
This type of overlap leads to a delocalisation (also known as no-bond resonance) of the π electrons, making the molecule more stable.
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(c) H2O2 (aq) + Fe 2+ (aq) → Fe3+ (aq) + H2O (l) (in acidic solution)
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(i) 300 atoms of A + 200 molecules of B
(ii) 2 mol A + 3 mol B
(iii) 100 atoms of A + 100 molecules of B
(iv) 5 mol A + 2.5 mol B
(v) 2.5 mol A + 5 mol B
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At 0°C, the density of a certain oxide of a gas at 2 bar is same as that of dinitrogen at 5 bar. What is the molecular mass of the oxide?
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(i) 1 g Au (s)
(ii) 1 g Na (s)
(iii) 1 g Li (s)
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Density of a gas is found to be 5.46 g/dm3 at 27 °C at 2 bar pressure. What will be its density at STP?
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