When brewing coffee what happens to the water molecules?

1. Heating:

* Increased Kinetic Energy: As water is heated, its molecules gain kinetic energy. They move faster and vibrate more vigorously.

* Weakening of Hydrogen Bonds: The hydrogen bonds that hold water molecules together weaken due to increased thermal motion. This allows the water to absorb more heat and reach a higher temperature.

* Phase Change: At 100°C (212°F), the water molecules have enough energy to overcome the intermolecular forces holding them in a liquid state. They transition into a gaseous state, becoming steam.

2. Extraction:

* Solvent: The hot water acts as a solvent, extracting soluble compounds from the coffee grounds.

* Diffusion: The water molecules move around the coffee grounds, colliding with the grounds' surface. This creates a concentration gradient between the water and the grounds, causing soluble compounds to move from the grounds into the water.

* Solubility: The solubility of compounds in the coffee grounds varies. Some dissolve easily (like caffeine), while others are less soluble (like oils).

* Temperature Dependence: The solubility of many compounds increases with temperature. Hot water extracts more from the coffee grounds than cold water.

3. Cooling:

* Heat Loss: As the brewed coffee cools, the water molecules lose kinetic energy and their movement slows down.

* Re-establishment of Hydrogen Bonds: The hydrogen bonds between water molecules start to re-form. This contributes to the final texture and mouthfeel of the coffee.

In Summary:

Coffee brewing is a complex process involving multiple physical and chemical changes. The water molecules play a key role in:

* Absorbing heat and becoming a solvent.

* Extracting soluble compounds from the coffee grounds.

* Cooling down and affecting the final texture of the coffee.