You get this from the admiral in the War Room after the Geth Dreadnaught mission.

Here is a G4 walk through of the mission.

How do I receive the Rannoch: Admiral Koris mission?
$$\ce{H2O~(l) + NaCl~(s) -&gt;[\Delta] Na+~(aq) + Cl^{-}~(aq)}$$

When table salt is placed in water, it dissolves due to the polarity of water molecules. When solvation takes place, negatively polar sides of water molecules attach to $\ce{Na+}$ ions, and positively polar sides of water molecules attach to $\ce{Cl-}$ ions. The ions are then carried away by water molecules through diffusion. Since the sodium is now isolated from the chlorine, what keeps it from violently exploding with water in the following chemical reaction?

$$\ce{2Na + 2H2O -&gt; 2 NaOH + H2}$$

Also, since chlorine is poisonous, wouldn't that make drinking salted water extremely lethal?
