Glass is primarily composed of silicon dioxide (SiO2), which reacts with hydrofluoric acid (HF) to produce silicon tetrafluoride (SiF4).

Reaction:
SiO2 + 4HF → SiF4 + 2H2O

Explanation:
1. Composition of Glass:
- Glass is an amorphous solid made from a mixture of silica (SiO2), soda (Na2CO3), and lime (CaCO3).
- The main component of glass is silicon dioxide (SiO2), which is responsible for its transparency and physical properties.

2. Reaction with Hydrofluoric Acid:
- Hydrofluoric acid (HF) is a strong acid that can react with silicon dioxide in glass.
- The reaction between silicon dioxide and hydrofluoric acid results in the formation of silicon tetrafluoride (SiF4) and water (H2O).
- The balanced chemical equation for the reaction is: SiO2 + 4HF → SiF4 + 2H2O.

3. Formation of Silicon Tetrafluoride:
- Silicon tetrafluoride (SiF4) is a volatile compound that is formed during the reaction between glass and hydrofluoric acid.
- SiF4 is a colorless gas with a pungent odor.
- It is used in various industrial applications, such as in the production of optical fibers, electronics, and as a precursor for the synthesis of other silicon compounds.

4. Other Products:
- The reaction also produces water (H2O) as a byproduct.
- The water generated in the reaction is in the form of liquid.

In conclusion, when glass reacts with hydrofluoric acid, it produces silicon tetrafluoride (SiF4) and water (H2O) as products. SiF4 is a volatile gas that is commonly used in industrial applications, while water is generated as a byproduct of the reaction.