acid question

[onlyfknhuman]

300 ml of a 0.35 M Ca(OH)2 solution was reacted with 300 ml of 0.40 M HCl .

What is the Ph of the resultant solution

Answer says 13.18

Ive done thousands of these questions, but i dont know what im doing wrong!! i cant seem to get 13.18

much appreciated

[Mao]

OH- is in excess, after reaction, we have





assuming this is at 25 degree celsius



(two sig figs)

[onlyfknhuman]

thanks, ! omg i forgot that oh- is in excess

[onlyfknhuman]

Another note;

Only gases will respond to changes in pressure. Solutions will respond to
changes in concentration.

Doesnt this screw eveyrthing up? ive never heard of this >_< and ive been getting eveyrthing right in equilibruim. can someone confirm this

[bucket]

It's not that confusing.
By change in concentration, you could be adding more volume - this is like decreasing the pressure with gasses. There is more space between particles so the reaction producing the more particles is favored.

[Collin Li]

Yes, this is approximately true. Liquids don't have enough degrees of freedom to be significantly affected by a pressure change.

Gases, on the other hand, are clearly affected by the ideal gas equation:



This is also intuitive as gases are free molecules with no kind of 'stickyness' or structure to the other molecules, so a pressure change will clearly affect its concentration or density.

And given that the concentrations are ultimately what is responsible for equilibrium (the reaction quotient), then this is how pressures affect gases. The same cannot be said about liquids.

[onlyfknhuman]

Ah i just needed some confirmation thanks, cause ive never really considered this. So thanks for that.

Btw. How fussy are examiners over states? is it better to guess states then leave them out if not sure?