Heavy Sticky Water

Question 1

Density of water at 0°C and 1 atmosphere

Answer 1

1.0 g cm-3 per definition

Question 2

How and why is saltwater’s minimum density and freezing point different than freshwaters?

Answer 2

Because of the changed intermolecular attractions due to the electrostatic forces from its constituent ions, seawater does not have the same temperature of minimum density as freshwater.
It contracts down to its freezing point, well below 0°C because of colligative effects.

Question 3

Is water incompressible?

Answer 3

No, at deep ocean pressures it contracts substantially.

Question 4

Actual density (rho, ρ) changes with depth (z) about how much?

Answer 4

Δρ = 0.0000044 g cm-3 /atmosphere pressure

Question 5

Compression of water under pressure affects organic molecules in deep-sea organisms. Why and how?

Answer 5

Enzymatic modulation of organic reaction rates depends on very weak forces among atoms at the active sites of enzymes, hydrogen bonds and Van Der Waals forces.
Small distortions of an enzyme’s shape can change effectiveness of bonding or bond release.

Question 6

How deep down do you have to go before compression of the water affects organic molecules?

Answer 6

The effect becomes important at depth differentials of 1000 meters. (100 atmospheres).

That means that biochemistry and viability of an organism changes when it is brought to the surface, and biochemical reactions of deep sea bacteria must be studied in pressure chambers.

Enzymes do not “break” but become active again once they are put under pressure.