everyday chemistry - Can drinking a lot of water be fatal?

I vaguely recall having heard that drinking too much water can, over time, prove fatal to the human body.

Nothing special about the water; not distilled or de-ionized or anything … just plain ol' water.

Now the reason that accompanied this "fact", was that drinking too much water serves to dilute, and thereby, disrupt the electrolyte balance in all (living) body tissue. This in turn, messes with the sodium-potassium pump present in cells leading to loss of functionality of cells.

Now I can't seem to find the source of that information, but I do recall it wasn't particularly trustworthy.

So what I want to know is:

1. 
   

   Is it true, that drinking a lot of water can be fatal?

   
   
   


2. 
   

   If so, is it because the electrolyte concentration inside and outside cells are "diluted"?

   
   


3. 
   

   Does this affect all (living) tissue equally?**

   
   

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Edit:

I fail to see why this was put on hold as a personal medical question. I vote to reopen this on the grounds that it does not:

a) Ask for advice on treating water intoxication

b) Suggest, promote or request, in any way, alternative forms of medicine.

Answer

Based on what I gathered from this Wikipedia article, Yes.

Drinking copious amounts of water can prove fatal. The proper term is "Water intoxication".

When you start taking in a lot of water (by "a lot" I mean more water than your body can excrete via sweat or urine), the interstitial fluid that bathe the cells that form your (living) tissue end up getting "diluted", i.e- the concentration of ions like $\mathrm{Na^{+}}$ is greatly reduced. The result? The concentration of ions in the interstitial fluid is far lower than the concentration of ions inside the cells it surrounds. Thinking of this in another way; the concentration of water in the interstitial fluid is far higher than the concentration of water inside the cells.

Ever soaked dry raisins in water? Over time they begin to absorb water and swell up as a consequence of the concentration gradient set up between the tissue in the raisin (Low concentration of water) and the water in the bowl. This phenomenon, where water flows from a region of higher concentration (of water) to a region of lower concentration (of water) across a semi-permeable membrane is called osmosis.

It's pretty much the same thing in the case of water intoxication. A concentration gradient has been set up between cells and the interstitial fluid that surrounds it. So water begins to flow into the cell, and the cell swells up quite a bit, resulting in a build-up of turgor pressure

This increase in turgor pressure will be seen to varying degrees in all sorts of (living) tissue, especially tissue that is highly vascular. An important example would be neural tissue, particularly that in the brain. This swelling up of tissue results in an increase in intracranial pressure which can lead to loss of functionality over time. This is what makes water intoxication so lethal.

There isn't really much about the chemistry of water that's responsible for this, apart from osmosis that is.

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Addendum:

Drinking a ton of water isn't the only way for water to build up in potentially lethal amounts in the body. Hyponatremia, which refers to a condition of low (below-normal) sodium levels in body fluids, can also lead to water accumulating in the body in excess.

parsha torah portion - Splitting the Makot

The splitting of the Parshiot usually make, at least, some sense. However, in the next two Parshiot the plagues are split up (7 in the first, 3 in the second). Are there sources on why this may be? Is it teaching us something or was it done simply for time and length of parshas sake (I can't imagine this is the case, but maybe).

Answer

Abarbanel discusses this and gives two reasons why the parshiyos were split this way (which, incidentally, are the reasons @LarryK and @GershonGold have offered).

1. The plague of arbeh was chosen to begin Parshas Bo with because it begins the makkos for which Pharaoh began to fear the plagues and negotiate with Moshe before the plague started.


2. All the last three makkos took place in the dark. The locusts "darkened the land of Egypt" with their sheer mass. Choshech, clearly. Bechoros was at exactly midnight (although it would have been full moon, so it probably wasn't completely dark).

[Also, it makes the mnemonic work. First two letters of each parsha, Va'era and Bo add up in gematria to how many plagues are within.]

halacha - Can a man miss tefilah with a minyan because his wife is overwhelmed with the children?

Assume a scenario where a man's wife requires extra help at home during a busy part of the day and requests that her husband skip minyan (and daven alone) in order to help her. (For example, let's say the woman recently gave birth and is very overwhelmed, and she requires extra help getting the children ready for school).

What considerations would be relevant to determining whether a man may skip prayer with a minyan under such a circumstance?¹

Please provide sources that allow/prohibit this.

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¹ _{For example: (1.) Whether this is a case of a mitzva that cannot be handled by someone else. (1a.) If it can be handled by someone else, but only for a price. (2.) How this will affect harmony in the household. (3.) How it will affect the children's education if you help them go to school. (3a.) How it will affect the children's education if you show them that you will continue going to minyan under the circumstances. (4.) Whether the man lives in close proximity to a minyan. (5.) Whether the man would be the tenth person at the minyan, or is the only person that can perform some essential function, such as Torah reading, at the minyan.}

translation - よかろう - What does it mean? Where does it come from?

This is another question that's come from a 昔話。

We have the following section:

大きい箱と小さい箱がありますが、どちらがいいですか。
どちらも結構じゃが、どうしてもと言うのなら、小さいほうでよかろう。

I'm having trouble with the second sentence. My translation is:

• どちらも結構じゃが - Either one is fine. - Here, I think じゃ is a contraction of では and has the same effect as using です.



• どうしてもと言うのなら - If you say I must - の seems like the explanation modality to me.


• 小さいほうでよかろう - The little one would be better. - I'm guessing that ほうで is a less emphatic version of ほうが. Just going on context for よかろう meaning good.

What I'm really interested in is where よかろう came from. At first glance, it seemed like some crazy old volitional form (行こう!）, but It seems kind of ridiculous for there to be a volitional form of an adjective. It really seems like it could be the adjectival form of だろう. (I read something that sounded similar to this that was the adjectival form of だろう, but cannot find the link again.)

• What does よかろう mean?


• Is it equivalent to いいだろう?


• Is this just one of those old fashioned feeling Japanese grammatical forms?


• Is there a case where I could actually put this to use (other than reading 昔話)?

Answer

よかろう is not so different from いいだろう. The crucial part is the same. And your concern about having a volitional form for an adjective is right, but is only half way. If you worry about the volitional form, then why do you not worry about the plain ending form, past form, etc. of adjectives? If you decompose the adjectives, you can observe that all these endings are actually verb endings. They merely look like adjective endings because they are contracted.

よかろう < yoku ar-ou
(possibility form ou attached to the verb ar)
'it is probably good'

い/よいだろう < i/yoi de ar-ou
(possibility form ou attached to the verb ar)
'it is probably good'

い/よいでしょう < i/yoi des-you

(possibility form (y)ou attached to the verb des)
'it is probably good' (polite)

よかろう is slightly old fashioned, but is still in use when you either want to be formal or authoritative.

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じゃ in じゃが is not では but is the same as だ, which historically comes from である.

acid base - Can "Common Ion Effect" suppress the dissociation of water molecules in acidulated water?

$$\begin{align} \ce{H2O &<=> H+ + OH-} \\ K &= \frac{[\ce{H+}][\ce{OH-}]}{[\ce{H2O}]} \\ \ce{H2SO4 &<=> 2H+ + SO4^2-} \end{align}$$

In acidulated water water dissociates into its respective ions(though the dissociation is very less) and simultaneously acid dissociates into its respective ions.

Now as the acid (I have taken $\ce{H2SO4}$ here) also dissociates to give $\ce{H+}$ ions. So the $\ce{H+}$ ion concentration increases which in turn affects the equilibrium of $\ce{H2O}$ and favours the backward reaction forming $\ce{H2O}$ back. So can we say common ion effect has suppressed the dissociation of $\ce{H2O}$?

And if this is the case then why do we use acidulated water while performing the electrolysis of water? (I mean the common ion effect can suppress dissociation of water and we would get less $\ce{H+}$ and $\ce{OH-}$ ions in the medium which would lead to a lower yield if $\ce{H2}$ and $\ce{O2}$ gas.)

Answer

You have a couple of concepts mixed together in the wrong way.

(1) The ionization of water is typically written as

$\text{K}_\text{w} = \ce{[H+] \cdot [OH^-]}$

The assumption is that the ionization is so low that the concentration of water remains a constant. For a solution which is half water and half acetic acid that wouldn't be true of course.

(2) The dissociation and recombination of water molecules is a very fast reaction and occurs continuously in water.

$\ce{2H2O <=> H3O+ + OH-}$

(3) In reality the autoprotolysis of water is dependent on the activities of the $\ce{H+}$ and $\ce{OH-}$. So the relation is more properly written as

$\text{K}_\text{w} = a_\ce{H+} \cdot a_\ce{OH^-}$

In dilute solutions the activity is essentially the same as the concentration, but in more concentrated solutions the activity drops as the concentration increases because of the formation of clusters of ion pairs in solution.

Also the activity drops as the overall ionic strength of the solution increases for the same reason. So if you add $\ce{NaCl}$ to the solution, then the ionic strength of the solution increases and the activity of the hydronium ions and hydroxide ions decreases. So in concentrated $\ce{NaCl}$ the $\ce{Na+}$ and $\ce{Cl-}$ ions aren't really just "spectators."

(4) If you add $\ce{H2SO4}$ to distilled water then the acid will dissociate according to the following reactions:

$\ce{H2SO4 + H2O <=> H3O+ + HSO4-}\quad \quad \text{pK}_{\alpha1} = -3$

$\ce{HSO4- + H2O <=> H3O+ + SO4^{2-}}\quad \quad \text{pK}_{\alpha2} = 1.99$

The final pH will depend on the final concentration of the sulfate species which is commonly expressed as the molarity of the sulfuric acid. So if we diluting concentrated sulfuric acid we typically use

$\text{m}_1 \cdot \text{V}_1 = \text{m}_2 \cdot \text{V}_2$

where $\text{m}$ is the molarity of the solution and $\text{V}$ is the volume of the solution. This ignores the fact that in dilute solution the sulfuric acid isn't just $\ce{[H2SO4]}$ but that the overall sulfuric acid concentration is the sum of $\ce{[H2SO4]}$, $\ce{[HSO4^-]}$, and $\ce{[SO4^{2-}]}$.

(5) Acidifying an electrolysis solution isn't really about ion concentration since adding NaCl isn't as effective as adding HCl. The gist is that protons can move through solution very quickly since a water molecule can accept a proton from one direction to form hydronium and kick off a different proton in the other direction to form water again. So a net charge can move through solution quickly as a result of the chain reaction of such transfers. Thus any individual proton doesn't have to travel far.

CONCLUSION

The overall notion would be better expressed as that adding sulfuric acid to water increases the $[\ce{H+}]$ and reduces the $[\ce{OH-}]$ thus shifting the equilibrium for the autoprotolysis of water.

halacha - Starting Shabbat early during the summer

Is there an earliest time one may begin Shabbat during the summer months?

We were traveling south and stopped at a Jewish community for Shabbat. The Shul there davened Mincha friday at 6:10, then added an extra prayer between Mincha and Kaaballat Shabbat to add 3 or 4 minutes. The Rabbi's explanations was they needed to add the extra time so as too not daven Maariv before the "earliest allowed time". I never heard of that before and was confused since it was still daylight out while walking back after davening was over.

Answer

The earliest time that Shabbat may be accepted is called "Plag ha-Mincha", which occurs one and one quarter 'hours' before sunset. An 'hour' for this purpose, is defined as 1/12 of the day (from sunrise to sunset).

Is it acceptable in Japanese to write kanji characters in the Chinese style?

In Japanese, is it acceptable to write kanji letters in the Chinese style? For example, is it acceptable to write 田 with the 3rd and 4th strokes swapped, or 着 with the 6th and 7th strokes combined?