Question

Which one of the following does not have spª hybridized carbon? (a) acetone (b) acetic acid (c) acetonitrile (d) acetamide

Short answer

Acetone, acetic acid, and acetamide do not have sp hybridized carbon; acetonitrile does.

Step-by-step solution

Understanding Hybridization

Hybridization is a concept in chemistry where atomic orbitals mix to form new hybrid orbitals. The 'sp' hybridization involves the combination of one s and one p orbital, giving two hybrid orbitals that align linearly, and occurs in carbon atoms triple-bonded to nitrogen or carbon.

Identifying Each Compound's Structure

We will examine the molecular structures of each compound to identify if any carbon atom is sp hybridized. The molecular structures are: - Acetone: \((CH_3)_2CO\)- Acetic acid: \((CH_3COOH)\)- Acetonitrile: \(CH_3CN\)- Acetamide: \(CH_3CONH_2\)

Analyzing Acetone

Acetone, \((CH_3)_2CO\), contains a carbon atom double-bonded to an oxygen (carbonyl group), which results in sp² hybridization. There are no triple-bonded carbons, thus no sp hybridized carbon.

Analyzing Acetic Acid

Acetic acid, \((CH_3COOH)\), has a carbonyl group (C=O) and a hydroxyl group (O-H). The carbon atom in the carbonyl group is double-bonded to oxygen, resulting in sp² hybridization. There are no carbon-carbon triple bonds.

Analyzing Acetonitrile

Acetonitrile, \(CH_3CN\), has a carbon triple-bonded to nitrogen (C≡N). The carbon involved in the triple bond is sp hybridized, fulfilling the condition for sp hybridization.

Analyzing Acetamide

Acetamide, \(CH_3CONH_2\), features a carbonyl group where carbon is double-bonded to oxygen, which means the carbon is sp² hybridized. There are no carbon-carbon or carbon-nitrogen triple bonds.

Conclusion

Reviewing the structures, only acetonitrile has an sp hybridized carbon. Thus, the compounds acetone, acetic acid, and acetamide do not have sp hybridized carbon.

Key concepts

sp hybridization

In chemistry, 'sp hybridization' is crucial in explaining molecular structures. It occurs when one s orbital and one p orbital from the same atom combine, forming two identical sp hybrid orbitals. This hybridization is common in carbon atoms that form triple bonds, such as with nitrogen or carbon.

Here's a simple breakdown:

• The s orbital is spherical, while the p orbital is dumbbell-shaped.
• The merging of these orbitals results in two linearly aligned sp orbitals, creating a 180° angle between them.
• This geometry minimizes repulsion, making the structure more stable.

Acetonitrile ( (CH_3CN ), for example, features an sp hybridized carbon due to the triple bond between carbon and nitrogen.

molecular structures

Understanding molecular structures involves looking at the specific arrangement of atoms within a molecule. Different hybridizations affect a molecule's shape and bond angles.

Some key points to remember are:

• 'Sp hybridization' leads to linear structures, often associated with carbon-nitrogen triple bonds.
• 'Sp² hybridization' causes planar triangular structures, typical in carbonyl groups.
• 'Sp³ hybridization' results in a tetrahedral shape, common in saturated hydrocarbons.

By analyzing molecular structures, students can predict physical and chemical properties. For instance, acetonitrile's linearity due to its triple bond, contrasts with the triangular planar shape in acetone, due to its sp² hybridized carbon.

carbonyl group

The carbonyl group is a key functional group in organic chemistry, consisting of a carbon atom double-bonded to an oxygen atom. This group is found in numerous organic compounds, like acetone and acetic acid. The carbon in carbonyls involves 'sp² hybridization', resulting in 120° bond angles and a planar structure.

Characteristics of the carbonyl group include:

• The carbon atom in the carbonyl group is typically electrophilic, making it reactive with nucleophiles.
• It's a polar group due to the difference in electronegativity between carbon and oxygen, making the carbon-oxygen bond quite strong.
• This polarity allows carbonyls to participate in a variety of chemical reactions, playing a vital role in both ketones, like acetone, and carboxylic acids, such as acetic acid.

triple bond

A 'triple bond' is a type of covalent bond where three pairs of electrons are shared between two atoms. This bond is notably stronger and shorter than double bonds and is characteristic of certain types of organic compounds.

Key features include:

• Triple bonds are usually seen in alkynes and nitriles, like acetonitrile, contributing to linear molecule shapes due to 'sp hybridization'.
• The strength and shortness of the triple bond contribute to the stability and reactivity of the molecule.
• In a triple bond, one sigma bond is formed along with two pi bonds, which makes these types of bonds unique.

Understanding triple bonds is essential for recognizing the behavior and properties of molecules like acetonitrile.

sp² hybridization

'Sp² hybridization' explains the arrangement of atoms in molecules where carbon forms three sigma bonds. An example is its presence in carbonyl groups, like those in acetone and acetic acid.

Characteristics of 'sp² hybridization' include:

• It involves the mixing of one s and two p orbitals, forming three sp² hybrid orbitals, resulting in 120° bond angles.
• This hybridization leads to a trigonal planar shape, typical of molecules like ethene or compounds with a carbonyl group.
• The shape allows for substantial stability and reactivity, often making such molecules suitable for various chemical reactions like addition or substitution.

Knowledge of 'sp² hybridization' is fundamental for understanding the frameworks of many organic compounds and their reactivity.