1. A Review of General Chemistry

The C=O double bond has a dipole moment of about 2.4 D and a bond length of about 1.23 Å.

b. Use this information to evaluate the relative importance of the following two resonance contributors:

Which of the following molecules would you expect to have a dipole moment of zero?

a. CH₃CH₃

b. H₂C═O

c. CH₂Cl₂

For each alkene, indicate the direction of the dipole moment. For each pair, determine which compound has the larger dipole moment.

c. cis-1,2-dibromo-1,2-dichloroethene or cis-1,2-dichloroethene

A single bond between two carbons with different hybridizations has a small dipole. What is the direction of the dipole in the indicated bonds?

a.

b.

Show the ionic compound that you would expect to form between the given metal and nonmetal. Label the charges on each species.

(b) Mg and Br

Which of the solvents are apolar and polar?

For each pair of compounds, predict the one with a higher boiling point. Which compounds have zero dipole moments?

a. cis-1,2-dichloroethene or cis-1,2-dibromoethene

Explain why CH₃Cl has a greater dipole moment than CH₃F even though F is more electronegative than Cl.

Which of the following has a polar covalent bond?

CH₃NH₂ CH₃CH₃ CH₃F CH₃OH

Sulfur dioxide has a dipole moment of 1.60 D. Carbon dioxide has a dipole moment of zero, even though C―O bonds are more polar than S―O bonds. Explain this apparent contradiction.

Which of the following has

a. the most polar bond?

b. the least polar bond?

NaI LiBr Cl₂ KCl

Which compound has the greater electron density on its nitrogen atom?

Which of the following molecules would you expect to have a dipole moment of zero?

d. NH₃

e. H₂C═CH₂

f. H₂C═CHBr

In a covalent bond, are electrons always shared equally between the atoms involved?

The C=O double bond has a dipole moment of about 2.4 D and a bond length of about 1.23 Å.

a. Calculate the amount of charge separation in this bond.