sublimation
the change of a substance from solid to vapor without passing through the liquid state is called sublimation. sublimation at stp typically occurs in materials held together by very weak intermolecular forces. for example, carbon dioxide (co₂) is nonpolar and is therefore held together in solid, “dry ice” form via very weak dispersion forces. since these intermolecular forces are very weak, it does not take much energy to completely break them versus weakening them. therefore, the liquid phase is completely skipped. because of this, solids will also have a vapor pressure. sublimation occurs in solids with vapor pressures that exceed atmospheric pressure.
noticing patterns can be a first step to organizing phenomena and exploring why and how the patterns occur.
19 ccc stability and change predict whether or not the substances in the table will sublime at stp. base your predictions only on the type of bond or intermolecular force holding the solid together.
table: will it sublime? with columns substance, type of bond or intermolecular force, sublime at stp? and rows carbon dioxide (co₂), hydrogen fluoride (hf), calcium chloride (cacl₂), naphthalene (c₁₀h₈), iodine (i₂), sodium chloride (nacl), water (h₂o)

Question

Accepted Answer

To solve this, we analyze each substance's intermolecular forces/bonds and determine if they are weak enough for sublimation at STP (sublimation occurs in solids with very weak intermolecular forces, skipping the liquid phase).

### 1. Carbon dioxide ($\ce{CO_2}$)
- **Type of Bond/Intermolecular Force**: Nonpolar covalent bonds in molecules; intermolecular forces are weak London dispersion forces (since $\ce{CO_2}$ is nonpolar).
- **Sublime at STP?**: Yes (matches the example in the text; weak dispersion forces allow skipping the liquid phase).

### 2. Hydrogen fluoride ($\ce{HF}$)
- **Type of Bond/Intermolecular Force**: Polar covalent bond (H - F); intermolecular forces are strong hydrogen bonds (due to F’s high electronegativity).
- **Sublime at STP?**: No (strong hydrogen bonds require more energy to break; liquid phase is not skipped).

### 3. Calcium chloride ($\ce{CaCl_2}$)
- **Type of Bond/Intermolecular Force**: Ionic bond (between $\ce{Ca^{2+}}$ and $\ce{Cl^-}$ ions); ionic bonds are very strong.
- **Sublime at STP?**: No (strong ionic bonds require significant energy; liquid phase is not skipped).

### 4. Naphthalene ($\ce{C_{10}H_8}$)
- **Type of Bond/Intermolecular Force**: Nonpolar covalent bonds in molecules; intermolecular forces are weak London dispersion forces (naphthalene is nonpolar).
- **Sublime at STP?**: Yes (weak dispersion forces allow sublimation; naphthalene is known to sublime).

### 5. Iodine ($\ce{I_2}$)
- **Type of Bond/Intermolecular Force**: Nonpolar covalent bond (I - I); intermolecular forces are weak London dispersion forces (nonpolar diatomic molecule).
- **Sublime at STP?**: Yes (weak dispersion forces; iodine is known to sublime at STP).

### 6. Sodium chloride ($\ce{NaCl}$)
- **Type of Bond/Intermolecular Force**: Ionic bond (between $\ce{Na^+}$ and $\ce{Cl^-}$ ions); ionic bonds are very strong.
- **Sublime at STP?**: No (strong ionic bonds; liquid phase is not skipped).

### 7. Water ($\ce{H_2O}$)
- **Type of Bond/Intermolecular Force**: Polar covalent bonds (O - H); intermolecular forces are strong hydrogen bonds.
- **Sublime at STP?**: No (strong hydrogen bonds; liquid phase is not skipped, though ice can sublime slowly in some conditions, but at STP, liquid water is stable).

### Filled Table:

| Substance               | Type of Bond or Intermolecular Force       | Sublime at STP? |
|-------------------------|--------------------------------------------|-----------------|
| Carbon dioxide ($\ce{CO_2}$) | London dispersion forces (nonpolar)        | Yes             |
| Hydrogen fluoride ($\ce{HF}$) | Hydrogen bonding (polar)                   | No              |
| Calcium chloride ($\ce{CaCl_2}$) | Ionic bonding                              | No              |
| Naphthalene ($\ce{C_{10}H_8}$) | London dispersion forces (nonpolar)        | Yes             |
| Iodine ($\ce{I_2}$)       | London dispersion forces (nonpolar)        | Yes             |
| Sodium chloride ($\ce{NaCl}$) | Ionic bonding                              | No              |
| Water ($\ce{H_2O}$)       | Hydrogen bonding (polar)                   | No              |

### Key Logic:
Sublimation at STP requires **very weak intermolecular forces** (so the liquid phase is skipped). Substances with strong forces (ionic bonds, hydrogen bonds) do not sublime at STP; those with weak London dispersion forces (nonpolar molecules) do.

Sovi.AI - AI Math Tutor

QUESTION IMAGE

Question

Explanation:

1. Carbon dioxide (\(\ce{CO_2}\))

2. Hydrogen fluoride (\(\ce{HF}\))

3. Calcium chloride (\(\ce{CaCl_2}\))

4. Naphthalene (\(\ce{C_{10}H_8}\))

5. Iodine (\(\ce{I_2}\))

6. Sodium chloride (\(\ce{NaCl}\))

7. Water (\(\ce{H_2O}\))

Filled Table:

Key Logic:

Answer: