Question

I do not understand what is meant by liquid water molecules in an open lattice structure: If it is a liquid how can there be a lattice? I can imagine some weak transitory hydrogen bonds over several molecules forming nearly independent blobs above and near melting temperatures. Is that a correct view? Or is it better to think of this as that water actually freezes and ice forms at 4C but between 0C and 4C with many sites are left open?

Following this my question is whether an external electric field can affect these bonds, the average number of molecules being in a bonded state, and thus change/vary, the negative thermal expansion coefficient?

Answer 1

In liquid water, hydrogen bonds are continually breaking and reforming, creating a transient open lattice structure that is less organized than the permanent structure found in ice. External electric fields can affect these hydrogen bonds due to water's dipole nature, potentially altering properties such as thermal expansion coefficient. Yet, the effect is complex and not fully characterized.

Step-by-step explanation:

The term liquid water molecules in an open lattice structure refers to the transient and flexible network of hydrogen bonds that exist in liquid water.

Unlike in solid ice, where each water molecule is engaged in forming a stable and well-defined open, cage-like structure due to hydrogen bonds, liquid water has a more dynamic scenario. Here, hydrogen bonds continually break and reform due to the molecules' thermal motion.

At temperatures closer to freezing, some stronger and more organized hydrogen bond structures reminiscent of ice can occur transiently, even though the water remains in the liquid state.

This does not mean that liquid water turns into ice at 4°C, but it suggests that there are transiently stable hydrogen-bonded structures within the liquid. When an external electric field is applied, it can affect these hydrogen bonds because of water's dipole nature, potentially altering properties like the thermal expansion coefficient.

However, the relationship between the external electric fields and water's properties, especially its thermal expansion, is complex and would depend on the size, direction, and strength of the electric field, as well as the state of the water in question.