Tag: hydroxy compounds and ethers

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Questions Related to hydroxy compounds and ethers

Multiple choice chemistry hydroxy compounds and ethers physical properties of phenol physical properties of alcohols and phenols organic compounds with functional group containing oxygen (part-1)

Alcohols containing only up to ___________ carbon atoms are completely miscible with water.

  1. three

  2. four

  3. five

  4. two
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Hydroxyl group makes the alcohol molecule polar and these are used as protic solvents. Two opposing solubility trends in alcohols are the tendency of the polar OH to promote solubility in water and the tendency of the carbon chain to resist it. So, methanol, ethanol, propanol are miscible in water as the OH group overcomes the short carbon chain.

Multiple choice chemistry hydroxy compounds and ethers physical properties of phenol physical properties of alcohols and phenols organic compounds with functional group containing oxygen (part-1)

Among the following compounds, the most acidic is:

  1. p-nitrophenol

  2. o-hydroxybenzoic acid

  3. p-toluic acid

  4. p-hydroxybenzoic acid
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Order of strength is ortho hydroxy benzoic acid > Toulic acid > p-hydroxy benzoic acid > p nitro phenol. Ortho hydroxy acid is strongest acid due to stabilisation conjugate by intermolecular H-bond which outweigh the electron donating resonance effect of –OH

 

Multiple choice chemistry hydroxy compounds and ethers physical properties of phenol physical properties of alcohols and phenols organic compounds with functional group containing oxygen (part-1)

In which of the following solvents, KI has highest solubility? The dielectric constant $(\epsilon)$ of each liquid is given in parentheses.

  1. $ C _{6}H _{6}(\epsilon =0)$
  2. $(CH _{3}) _{2}CO(\epsilon =21)$
  3. $CH _{3}OH(\epsilon =32)$
  4. $CCl _{4}(\epsilon =0)$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

KI is an ionic compound. Hence, it will be most soluble in apolar solvent, which has a high value of dielectric constant. Hence, $CH _3OH$ with the highest value of dielectric constant among the given options will provide high solubility.

Multiple choice chemistry hydroxy compounds and ethers physical properties of phenol physical properties of alcohols and phenols organic compounds with functional group containing oxygen (part-1)

Phenol is an organic compound even though it is soluble in water due to the presence of:

  1. ionic bonding

  2. covalent bonding

  3. hydrogen bonding

  4. coordinate bonding
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Phenol is an organic compound even though it is soluble in water due to the presence of hydrogen bonding. Phenol has hydroxyl group which is involved in the formation of hydrogen bonds with water. It increases the solubility.  Hydrogen bonding is possible when $H$ atom is attached to electronegative $N,\ O$ or $F$ atom.

Multiple choice chemistry hydroxy compounds and ethers alcohol nomenclature of alcohols and phenols introduction to alcohols

Tertiary alcohol on treatment with cyanide in presence of conc. ${ H } _{ 2 }{ SO } _{ 4 }$ gives corresponding primary amine. This reaction is called as :

  1. Schmidt reaction

  2. Curtius degradation

  3. Leuckart reaction

  4. Ritter reaction
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The reaction of a tertiary alcohol with hydrogen cyanide in the presence of concentrated sulfuric acid to yield a primary amine is known as the Ritter reaction. It involves the formation of a carbocation intermediate followed by the addition of a nitrile.

Multiple choice chemistry hydroxy compounds and ethers physical properties of ethers ethers alcohols, phenols and ethers

Ethers have lower boiling points than their corresponding isomeric alcohols because of?

  1. hydrogen bonding in alcohols that is absent in ethers due to low polarity

  2. hydrogen bonding in ethers due to high polarity

  3. insolubility of ethers in water due to less polarity

  4. inertness of ethers as compared to alcohols.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ethers ROR cannot form intermolecular Hydrogen bond due to the absence of H attached with the electronegative atom as N/O/F, but in case of alcohols, they have -OH which can undergo intermolecular hydrogen bonding and that increases their boiling point.

Thus, Ethers have lower boiling points than their corresponding isomeric alcohols because of hydrogen bonding in alcohols that is absent in ethers due to low polarity.

Multiple choice chemistry hydroxy compounds and ethers physical properties of ethers ethers alcohols, phenols and ethers

Correct order of boiling points among following is: $\underset{(X)}{CH _3(CH _2) _3CH _3}, \,\,\,\,\underset{(Y)}{C _2H _5OC _2H _5},\,\,\,\,\,\,\underset{(Z)}{CH _3(CH _2) _3OH}$

  1. X > Y > Z

  2. Y > X > Z

  3. Z > X > Y

  4. Z > Y > X
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The boiling point of a molecule depends on the strength of intermolecular interaction such as Vandewaal's attraction, hydrogen bonding etc.

Alkanes, such as $\underset{X}{CH _3(CH _2) _3CH _3}$, being non-polar have the weakest force of attraction called dispersion or London forces.
Ethers, such as $\underset{(Y)}{C _{2}H _{5}OC _2H _5}$, have small dipole moment or weakly polar thus have dipole-dipole interaction. This is stronger than the London forces.
Alcohols, such as $\underset{(Z)}{CH _3(CH _2) _3OH}$, are polar molecules, therefore, have strong dipolar interaction. Moreover, they form an intermolecular hydrogen bond that further increases the attraction (association).

Hence the order of their boiling point will be:
$\underset{(Z)}{CH _3(CH _2) _3OH}>\underset{(Y)}{C _{2}H _{5}OC _2H _5}>\underset{X}{CH _3(CH _2) _3CH _3}$

OR $Z>Y>X$