Chemistry

9.31. (H⁺ and OH⁻ ions) of water molecule react with a compound to form products. For example:

NaH+H₂O → NaOH+H₂

Hydration is defined as the addition of one or more water molecules to ions or molecules to form hydrated compounds. For example:

CuSO₄+5H₂O → CuSO₄.5H₂O

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Williamson synthesis is basically a S_N2 reaction of a primary alkyl halide with an alkoxide ion. The basic mechanism for this reaction is

Now consider this reaction,

This reaction proceeds as conventional Williamson synthesis. But if secondary or tertiary alkyl halides are taken in place of primary alkyl halides, then elimination would compete over substitution reaction, which will result in the formation of alkenes. The reason is alkoxides are better nucleophiles as well as strong bases. Therefore, they react with alkyl halides resulting in an elimination reaction.

9.30. No, D₂O is injurious to human beings, plants and animals.

9.29. Water is highly polar in nature. That is why it has high dielectric constant and high dipole moment. Because of these properties, water is a universal solvent.

Water is good solvent for ionic compounds but poor solvent for covalent compounds. It can hydrolyse ionic compounds.

9.28.  (i) Major part of all living system is made of water.

(ii) It constitutes about 65 – 70% of body weights of animals and plants.

(iii) Some properties of water like high specific heat, thermal conductivity, surface tension, high polarity allow water to play a major role in biosphere.

(iv) Because of high heat of vaporisation it is responsible to regulate temperature of living beings.

(v) It is an excellent fluid for the transportation of minerals and nutrients in plants.

(vi) It is also required for photosynthesis in plants.

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Ethoxy-2-methylpropane

Chloro-1-methoxyethane 4-Nitroanisole

1-Methoxypropane

Ethoxy-4,4-dimethylcyclohexane Ethoxy benzene

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Due to the presence of -OH group, ethanol undergoes intermolecular hydrogen bonding which results in the association of molecules.

Therefore, extra energy is required to break those hydrogen bonds. Whereas methoxymethane does not undergo those hydrogen bonding which implies ethanol has a higher boiling point than that of methoxymethane.

9.27. No, demineralised or distilled water is not fit for drinking purposes. It can be made useful by adding required amount of ions which are useful for our body.

9.26. Water free from salts and minerals is called Demineralized water. Ion exchange method is used for this process. The ions present in the water bind to the positively or negatively charged sites on a resin when water is passed through the column packed with resin.