When limestone, sand, and soda (sodium carbonate) are heated, they undergo a chemical reaction to form glass. This process, known as glassmaking, typically involves melting the raw materials at high temperatures in a furnace.

Limestone (calcium carbonate, CaCO3) serves as a source of calcium oxide (CaO), which acts as a fluxing agent. It helps to lower the melting point of the mixture and promotes the formation of a liquid phase.

Sand (silicon dioxide, SiO2) provides the primary component of glass – silica. When heated, silica undergoes a transformation into a molten state and plays a crucial role in determining the glass's properties, such as its strength and durability.

Soda (sodium carbonate, Na2CO3) acts as a secondary fluxing agent, aiding in the melting process and further reducing the mixture's melting temperature. It also contributes to the glass's chemical composition and can influence its characteristics like clarity, color, and thermal expansion properties.

When these materials are heated together at temperatures typically ranging from 1400 to 1600 degrees Celsius (2552 to 2912 degrees Fahrenheit), they react and fuse to form a molten glass liquid. This liquid is then shaped and cooled in a controlled manner to create various types of glass products.

The proportions and specific types of raw materials used can vary depending on the desired properties and characteristics of the final glass product.