Question on electrostatics

[Temperature101]

---

Members do not see this ad.

This might be an easy question, but I am having trouble picturing it. Can someone explain?

When NaCl dissociates in pure water (H2O), the net charge of the electrolytic solution:

A. becomes negative.
B. becomes positive.
C. becomes neutral.
D. becomes positive or negative, depending upon the relative Na+ and Cl- concentrations.

The answer is C

 

[ztaxin]

This might be an easy question, but I am having trouble picturing it. Can someone explain?

When NaCl dissociates in pure water (H2O), the net charge of the electrolytic solution:

A. becomes negative.
B. becomes positive.
C. becomes neutral.
D. becomes positive or negative, depending upon the relative Na+ and Cl- concentrations.

The answer is C

Net charge is the total charge of a given solution. It is sort of asking the "what does this look like from space" question about a given solution. Each molecule of NaCl dissolves into two ions, the sodium cation and chloride anion. The charges are Na+ and Cl-. Since dissolving each molecule yields two atoms with charges that cancel each other out, the net charge (total charge in the solution) should still be zero.

The answer is worded poorly. The net charge does not BECOME zero. it REMAINS zero.

 

[deleted329605]

Also remember, it's impossible to ever have a positively or negatively charged solution, it's just physically impossible.

 

[MD Odyssey]

Also remember, it's impossible to ever have a positively or negatively charged solution, it's just physically impossible.

Proton beam directed into H2O. Would wind up with a positively charged, acidic solution.

 

[deleted329605]

O cool! What would help maintain such a solutions stability? I'd imagine having an excess of positive charges would create an incredibly unstable mixture....

 

[BerkReviewTeach]

O cool! What would help maintain such a solutions stability? I'd imagine having an excess of positive charges would create an incredibly unstable mixture....

True that it would be unstable, but I think MD Odyssey's point is that it's not impossible to have a solution with a net charge. Putting an ionizing beam into a solution would eject electons and leave behind a cation-rich solution. It would be a highly unstable system, but it violates the impossible clause. It's test taking sensitivity that makes words like always, never, impossible, honest college football program jump out at you as things that just aren't right.