* Hydrogen chloride (HCl) is a gas at room temperature. It's a colorless gas with a pungent, irritating odor.
* Hydrochloric acid (HCl) is an aqueous solution of hydrogen chloride gas. This means that HCl gas is dissolved in water. It's a colorless, highly corrosive liquid with a strong, acrid odor.
Here's a table summarizing the differences:
| Feature | Hydrogen Chloride (HCl) | Hydrochloric Acid (HCl) |
|-------------------|--------------------------|---------------------------|
| State of Matter | Gas | Aqueous solution |
| Appearance | Colorless gas | Colorless liquid |
| Odor | Pungent, irritating | Strong, acrid |
| Conductivity | Non-conductive | Conductive |
Key points to remember:
* Hydrogen chloride (HCl) is the chemical compound itself.
* Hydrochloric acid (HCl) is the solution formed when HCl gas is dissolved in water.
In essence, hydrochloric acid is simply hydrogen chloride dissolved in water. This dissolution leads to the formation of hydronium ions (H3O+) and chloride ions (Cl-), which are responsible for the acidic properties of hydrochloric acid.
