Finding pH given molarity and volume problem

  • Thread starter pmart491
  • Start date
  • #1
pmart491
19
0

Homework Statement


If you mix 200mL of a 1.8M HCl solution with 300mL of a 1.16M NaOH solution, what will be the pH of the solution?

The Attempt at a Solution


Well I am really lost with this problem. I am pretty sure you need to convert each to moles.

.2L HCl x 1.8moles HCl
------------------
1L HCl

.3L NaOH x 1.16 moles NaOH
---------------------------
1L NaOH


HCl=.36moles

NaOH=.348moles

HCl + NaOH -> NaCl + H2O

not too sure where u go from there
 

Answers and Replies

  • #2
symbolipoint
Homework Helper
Education Advisor
Gold Member
6,903
1,572
The acid and the base react 1:1, so which is in excess, and by how much?
 
  • #3
pmart491
19
0
is it .36-.348=.012 moles of HCl which = number of H+ ions?

pH=-log(.012) = 1.92?
 
  • #4
pmart491
19
0
or do u have to change moles of HCl back to molarity?

.012moles HCl
-------------
.5L total

=.024

pH=-log(.024)=1.62
 
  • #5
symbolipoint
Homework Helper
Education Advisor
Gold Member
6,903
1,572
HCl in aqueous solution is strongly ionized, or completely ionized for most practical purposes. For pH, you want the hydrogen ion CONCENTRATION AS MOLARITY...., and then find the negative logarithm.
 
Last edited:
  • #6
pmart491
19
0
yea so itd be 1.62 right?
 
  • #7
Borek
Mentor
29,137
3,766
Yep, 1.62 it is.
 
  • #8
chemisttree
Science Advisor
Homework Helper
Gold Member
3,694
693
Welcome back, Borek! You were missed.
 
  • #9
Borek
Mentor
29,137
3,766
Welcome back, Borek! You were missed.

:blushing:

I am planning to spend some time here now ;)
 

Suggested for: Finding pH given molarity and volume problem

Replies
2
Views
803
  • Last Post
Replies
3
Views
619
Replies
7
Views
1K
Replies
22
Views
5K
Replies
2
Views
747
  • Last Post
Replies
3
Views
717
Replies
3
Views
766
  • Last Post
Replies
2
Views
1K
Replies
10
Views
2K
  • Last Post
Replies
1
Views
241
Top