Roughly how many water molecules are ionized at any given time in a sample of room-temperature wate
Answers
Explanation:
Water is an amphiprotic molecule, it can act as a very weak acid and a very weak base, donating protons to itself to a limited extent:
2H2O (l)⇌H3O+(aq)+OH−(aq)(1)
Individual molecules do not remain ionized for a long time, the reaction is rapid towards both sides of the equilibrium. The animation above shows the Grotthuss mechanism in which the protons tunnel from one water molecule to the next via hydrogen bonding. Auto-ionization of water occurs in a similar way with separation of ions H+ and OH–, which recombine in a matter of femtoseconds. The lifetime of the separated ions is about 70 microseconds and depends on the extent of hydrogen bonding, so it is shorter at lower temperatures.[1]
Applying the equilibrium law to the reaction above, we obtain
Kc=[ H3O+][OH−][ H2O ]2(2)
However, the concentration of water has a constant value of 55.5 mol dm–3 (the law of chemical equilibrium), and so its square can be multiplied by Kc to give a new constant Kw, called the ion-product constant of water:
Answer:
One in a billion
Explanation: