pH calculations... (1 Viewer)

[Maddy1012]

some step-by-step help for this question would be GREAT

Calculate the pH after 10.0mL of 0.01 mol L-1 HLC solution is diluted by the addition of 90.0ml of distilled water.

 

[xiao1985]

first of all, i'm going to assume what you have is HCl solution, not hlc...

now:
q1) how many moles of HCl are there in 10mL of 0.01 mol L-1 of HCl?
q2) knowing there are that many moles of HCl, (and 10 mL of the solution), after adding 90 mL of water, what is the volume of new solution?
q3) knowing the number of moles of HCl and volume, what's the concentration of HCl?
q4) what's the concentration of H+
q5) what's pH

 

[Maddy1012]

hahaha whoops... i meant HCL.. shows how good i am with a keyboard..
ok i did this..... i dont know if its the right answer tho

0.1x0.01=Px0.1

so.... p=0.1

then to find out the pH would u just do

-log(0.1)???

coz from that i got a pH of 2.. am i right? i just dont think it is.


also i have anther question...

how come -log(h+) doesnt work with everything when finding out a pH.. i own the dot point book and i was doing questions and it said.
determine the pH of

0.1 HCL

0.1 of something else?!?

but the pH of the two were different. explain lol.

 

[Bank$]

determine the pH of

0.1 HCL

0.1 of something else?!?

but the pH of the two were different. explain lol.

there are 2 things u have to consider
1. degree of ionisation
2. whether the 2nd substance is polyprotic

the 2 above will influence the Ph of the 2nd subtance

EDIT: cancel out the 1st point that does not alter the Ph

so yeah u have to check whether the 2nd substance is polyprotic e.g. sulfuric acid

 

[Forbidden.]

some step-by-step help for this question would be GREAT

Calculate the pH after 10.0mL of 0.01 mol L-1 HLC solution is diluted by the addition of 90.0ml of distilled water.

Hey, that's the exact same question I got in the exam and not many people got that right.

 

[Maddy1012]

there are 2 things u have to consider
1. degree of ionisation
2. whether the 2nd substance is polyprotic

the 2 above will influence the Ph of the 2nd subtance

EDIT: cancel out the 1st point that does not alter the Ph

so yeah u have to check whether the 2nd substance is polyprotic e.g. sulfuric acid

hey, thanks... btw... nice signature... hahaha