Choose the groups of molecules below in which all the molecules have a net dipole moment.

a. SiHCl3, O2, H2O
b. HF, H2ClCH2, H2O
c. HF, CH3Cl, H2O
d. CCl4, HCl, NH3
e. HF, H2O, N2

what is the answer?

c. All the others contain at leat molecule that has charge symmetry about two perpendicular axes, and therefore no dipole moment

To determine which groups of molecules have a net dipole moment, we need to consider the individual molecules' molecular geometry and the polarity of their bonds.

a. SiHCl3: The dipole moment of each Si-H bond cancels out with the dipole moment of the Si-Cl bond, resulting in no net dipole moment. Oxygen (O2) is a linear molecule with a 0 net dipole moment. However, H2O is a bent molecule with a net dipole moment. Therefore, group a does not consist of molecules with a net dipole moment.

b. HF: HF is a polar molecule with a net dipole moment. H2ClCH2 has a tetrahedral molecular shape, and the net dipole moment of its polar bonds cancels out, resulting in no net dipole moment. H2O has a bent molecular shape with a net dipole moment. Therefore, group b consists of molecules with a net dipole moment.

c. HF: HF is a polar molecule with a net dipole moment. CH3Cl has a tetrahedral molecular shape, and the net dipole moment of its polar bonds cancels out, resulting in no net dipole moment. H2O has a bent molecular shape with a net dipole moment. Therefore, group c consists of molecules with a net dipole moment.

d. CCl4: CCl4 has a tetrahedral molecular shape, and the net dipole moment of its polar bonds cancels out, resulting in no net dipole moment. HCl is a polar molecule with a net dipole moment. NH3 has a trigonal pyramidal molecular shape, with a net dipole moment. Therefore, group d consists of molecules with a net dipole moment.

e. HF: HF is a polar molecule with a net dipole moment. H2O has a bent molecular shape with a net dipole moment. N2 is a linear molecule with a 0 net dipole moment. Therefore, group e does not consist of molecules with a net dipole moment.

Based on the analysis above, the groups of molecules that have a net dipole moment are:
b. HF, H2ClCH2, H2O
c. HF, CH3Cl, H2O
d. CCl4, HCl, NH3

To determine if a molecule has a net dipole moment, you need to assess the polarity of its bonds and the overall molecular geometry.

Let's go through each group of molecules one by one:

a. SiHCl3, O2, H2O
- SiHCl3: Silicon tetrachloride (SiCl4) is a nonpolar molecule due to the tetrahedral geometry and the symmetrical distribution of the chlorine atoms around the central silicon atom. Therefore, it does not have a net dipole.
- O2: Oxygen gas (O2) consists of two oxygen atoms bonded by a double bond. It is nonpolar because the oxygen-oxygen bond is symmetrical and the molecule is linear, so it does not possess a net dipole.
- H2O: Water (H2O) has a bent molecular geometry and is a polar molecule since the oxygen atom is more electronegative than the hydrogen atoms. The bent shape and the unequal distribution of electron density create a net dipole moment.

Therefore, in group a, only H2O has a net dipole moment.

b. HF, H2ClCH2, H2O
- HF: Hydrogen fluoride (HF) is a polar molecule because fluorine is more electronegative than hydrogen, resulting in an uneven distribution of electron density. It has a net dipole moment.
- H2ClCH2: Dichloromethane (H2ClCH2) has a tetrahedral geometry with a chloromethane molecule attached to hydrogen. Due to the symmetrical arrangement of the chlorine atoms, it cancels out the polarities, resulting in a nonpolar molecule without a net dipole.
- H2O: Water (H2O) has a bent molecular geometry, as mentioned earlier, and is a polar molecule with a net dipole moment.

Therefore, in group b, both HF and H2O have a net dipole moment.

c. HF, CH3Cl, H2O
- HF: As mentioned earlier, HF is a polar molecule with a net dipole moment.
- CH3Cl: Chloromethane (CH3Cl) has a tetrahedral geometry with a chloromethane molecule attached to hydrogen. Due to the asymmetrical distribution of electron density, it is a polar molecule with a net dipole moment.
- H2O: As mentioned before, water (H2O) is a polar molecule with a net dipole moment.

Therefore, in group c, all three molecules (HF, CH3Cl, and H2O) have a net dipole moment.

d. CCl4, HCl, NH3
- CCl4: Carbon tetrachloride (CCl4) has a tetrahedral geometry with four chlorine atoms bonded to a central carbon atom. The symmetrical arrangement of the chlorine atoms cancels out their polarities, resulting in a nonpolar molecule without a net dipole.
- HCl: Hydrogen chloride (HCl) is a polar molecule due to the difference in electronegativity between hydrogen and chlorine. It has a net dipole moment.
- NH3: Ammonia (NH3) has a pyramidal molecular geometry, with the nitrogen atom bonded to three hydrogen atoms. Due to the asymmetry in electron density caused by the nitrogen being more electronegative, NH3 is a polar molecule with a net dipole moment.

Therefore, in group d, only HCl and NH3 have a net dipole moment.

e. HF, H2O, N2
- HF and H2O have already been discussed and found to have a net dipole moment due to their polar nature.
- N2: Nitrogen gas (N2) consists of two nitrogen atoms bonded by a triple bond sharing six electrons. The molecule is linear, with symmetrical distribution, resulting in a nonpolar molecule without a net dipole.

Therefore, in group e, only HF and H2O have a net dipole moment.

In summary, the groups of molecules in which all the molecules have a net dipole moment are:

b. HF, H2ClCH2, H2O
c. HF, CH3Cl, H2O
d. CCl4, HCl, NH3