Why does a glass of water evaporate more slowly if you put it in a refridgerator than if you put it near a fireplace? Why does a glass of water evaporate more slowly if you put it in a refridgerator than if you put it near a fireplace? The greater thermal energy causes a greater fraction of molecules to have enough energy to break away from the surface. The greater thermal energy weakens intermolecular forces between water molecules. As the temperature of the water increases, it expands, which leads to the increase of the surface area. As the temperature of the water increases, its viscosity decreases.