/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 45 Which of the following molecules... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 9: Problem 45

Which of the following molecules is (are) polar? For each polar molecule, indicate the direction of polarity-that is, which is the negative end and which is the positive end of the molecule. (a) \(\mathrm{BeCl}_{2}\) (c) \(\mathrm{CH}_{3} \mathrm{Cl}\) (b) \(\mathrm{HBF}_{2}\) (d) \(\mathrm{SO}_{3}\)

Short Answer

Expert verified
Polar molecules: CH3Cl (negative: Cl, positive: C-H region), HBF2 (negative: F, positive: B).

Step by step solution

01

Evaluating Polarity of BeCl2

Beryllium dichloride, \( \mathrm{BeCl}_{2} \), has a linear shape due to its two bonding pairs and no lone pairs on the central atom. Chlorine is more electronegative than beryllium, resulting in dipole moments that cancel each other out in a linear molecule. Therefore, \( \mathrm{BeCl}_{2} \)is nonpolar.
02

Evaluating Polarity of CH3Cl

Methyl chloride, \( \mathrm{CH}_{3} \mathrm{Cl} \), has a tetrahedral shape. The electronegativity difference between chlorine and carbon creates a significant dipole moment directed from carbon to chlorine. The shape does not allow for dipole cancellation, making \( \mathrm{CH}_{3} \mathrm{Cl} \) a polar molecule with the negative end at chlorine and the positive end at the carbon-hydrogen region.
03

Evaluating Polarity of HBF2

In \( \mathrm{HBF}_{2} \), hydrogen, boron, and fluorine are bonded to each other. Fluorine is highly electronegative compared to boron and hydrogen, thus creating a dipole and making the molecule polar. The negative end is towards the fluorine atoms and the positive end is near the boron atom.
04

Evaluating Polarity of SO3

Sulfur trioxide, \( \mathrm{SO}_{3} \), has a trigonal planar shape with no lone pairs on the central sulfur atom. Despite the electronegativity difference between sulfur and oxygen, this shape allows the dipole moments to cancel out, rendering \( \mathrm{SO}_{3} \) nonpolar.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Electronegativity
Electronegativity is a key concept in understanding molecular polarity. It refers to the ability of an atom to attract shared electrons in a chemical bond. An atom with high electronegativity, like fluorine, pulls electrons closer to itself compared to an atom with lower electronegativity, such as hydrogen. This creates a dipole, which is a separation of charges within the molecule.
In our exercise, we see this concept at play:
  • In \( \mathrm{BeCl}_2 \), chlorine has a higher electronegativity than beryllium, but the linear shape allows for dipole moments to cancel out, making the molecule nonpolar.
  • For \( \mathrm{CH}_3 \mathrm{Cl} \), the electronegative chlorine creates a strong dipole moment that doesn't get canceled due to the tetrahedral shape, resulting in a polar molecule.
  • The molecule \( \mathrm{HBF}_2 \) is polar because highly electronegative fluorine atoms create a dipole with the boron atom.
  • Meanwhile, with \( \mathrm{SO}_3 \), despite the difference in electronegativity between sulfur and oxygen, the symmetric trigonal planar shape cancels out dipoles, leading to a nonpolar molecule.
This highlights how electronegativity differences and molecular shape interplay to determine the polarity of a molecule.
Molecular Geometry
Molecular geometry describes the three-dimensional arrangement of atoms in a molecule, which affects the molecule's properties including its polarity. VSEPR (Valence Shell Electron Pair Repulsion) theory is often used to predict molecular shapes based on the repulsion between electron pairs.In terms of our exercise:
  • \( \text{BeCl}_2 \) has a linear geometry. With two bonding pairs and no lone electron pairs on the central beryllium atom, the opposing dipole moments between beryllium and the more electronegative chlorine effectively cancel out.
  • \( \text{CH}_3 \text{Cl} \) exhibits a tetrahedral shape. This results in a net dipole moment because the electrons are not symmetrically distributed, making it polar.
  • \( \text{HBF}_2 \) has a trigonal planar or distorted geometry, where the arrangement allows for a net dipole moment towards the fluorine atoms, making it polar.
  • \( \text{SO}_3 \) adopts a trigonal planar shape. Despite oxygen's higher electronegativity compared to sulfur, the symmetric arrangement ensures dipoles cancel, resulting in a nonpolar molecule.
Molecular shape is crucial because it directly influences how dipole moments interact and whether they will cancel out or reinforce one another.
Dipole Moment
Dipole moment is a measure of the separation of positive and negative charges in a molecule and is a vector quantity. It is determined by both the difference in electronegativity and the geometry of the molecule. The dipole moment is represented by an arrow pointing from the positive to the negative charge.To analyze the examples given:
  • For \( \text{BeCl}_2 \), although there are bonds with dipoles due to electronegativity differences, the linear structure causes them to cancel out and result in a net dipole moment of zero, indicating no overall polarity.
  • In \( \text{CH}_3 \text{Cl} \), the presence of a single electronegative chlorine atom leads to a significant dipole moment. The tetrahedral shape ensures this dipole remains unbalanced, making the molecule polar with the negative end towards chlorine.
  • In \( \text{HBF}_2 \), the unbalanced placement of fluorine atoms, which are more electronegative, results in a dipole moment pointing towards these atoms. This causes an overall molecule polarity.
  • Lastly, \( \text{SO}_3 \) possesses three identical dipoles in a trigonal planar configuration, allowing all its dipoles to cancel out, leaving the molecule with no net dipole moment and thus nonpolar.
Understanding dipole moments helps in predicting the interactions of molecules, such as their solubility and reactivity, based on polarity.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Which has the greater \(\mathbf{O}-\mathbf{N}-\mathbf{O}\) bond angle, \(\mathbf{N O}_{2}^{-}\) or \(\mathrm{NO}_{2}^{+} ?\) Explain briefly.

Compare the \(\mathrm{F}-\mathrm{Cl}-\mathrm{F}\) angles in \(\mathrm{ClF}_{2}^{+}\) and \(\mathrm{ClF}_{2}^{-} .\) Using Lewis structures, determine the approximate bond angle in each ion. Decide which ion has the greater bond angle and explain your reasoning.

Compare the carbon-oxygen bond lengths in the formate ion \(\left(\mathrm{HCO}_{2}^{-}\right),\) in methanol \(\left(\mathrm{CH}_{3} \mathrm{OH}\right),\) and in the carbonate ion \(\left(\mathrm{CO}_{3}^{2-}\right) .\) In which species is the carbon-oxygen bond predicted to be longest? In which is it predicted to be shortest? Explain briefly.

Which of the following compounds or ions do not have an octet of electrons surrounding the central atom: \(\mathbf{B F}_{4}^{-}\) \(\mathrm{SiF}_{4}, \mathrm{SeF}_{4}, \mathrm{BrF}_{4}^{-}, \mathrm{XeF}_{4} ?^{-}\)

Give the bond order for each bond in the following molecules or ions. (a) \(\mathrm{CN}^{-}\) (b) \(\mathrm{CH}_{3} \mathrm{CN}\) (c) \(\mathrm{SO}_{3}\) (d) \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}\)
See all solutions

Recommended explanations on Chemistry Textbooks

Physical Chemistry

Read Explanation

Making Measurements

Read Explanation

The Earths Atmosphere

Read Explanation

Chemical Reactions

Read Explanation

Chemical Analysis

Read Explanation

Nuclear Chemistry

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.