Question

Buffers resist change in pH in a system when

A. glucose (C6H12O6) is added to the system.
B. hydrogen chloride (HCl) is added to the system.
C. sodium chloride (NaCl) is added to the system.
D. sodium bromide (NaBr) is added to the system.

Answer 1

What do you think?

Answer 2

This is where Le Chatelier's principle comes in. When a system is at equilibrium and something disturbs that equilibrium, then the system responds by shifting the position of the equilibrium so as to minimize the effect of the disturbance.

For instance, if acid (H+) is added, then the equilibirum will shift to the left to use up some of the added H+ and make more undissociated HA. This keeps the H+ concentration very nearly the same, which of course keeps the pH very nearly the same, as well.

If some base (OH-) is added, then H+ reacts with OH- to make water, and the equilibrium shifts to the right to make more H+, thereby keeping the concentration of H+ very nearly the same, and keeping the pH very nearly the same.

It is incorrect to assume that there is no change in pH for a buffer. When acid or base is added to a buffer there are small changes in pH.

Answer 3

So lets rule some of these out, A would not work because it is a throw in (Something that will produce nothing by putting it into the reaction)

C would not work because it is a neutral salt, and because it is neutral, common sense would agree that nothing would change

D would not work because it is also a neutral salt.


Notice above how I wrote that a change would be if a strong acid or base was added to shift the equation, and we know that HCl is a very strong acid so ultimately it would be the

correct answer - B

Answer 4

Thank you so so so much. Great explanation. I really understand it now @alphadxg

Answer 5

:)