Finding pH given molarity and volume problem

  • Thread starter pmart491
  • Start date
  • #1
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 im really lost with this problem. Im 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
6,082
1,143
The acid and the base react 1:1, so which is in excess, and by how much?
 
  • #3
19
0
is it .36-.348=.012 moles of HCl which = number of H+ ions?

pH=-log(.012) = 1.92?
 
  • #4
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
6,082
1,143
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
19
0
yea so itd be 1.62 right?
 
  • #7
Borek
Mentor
28,562
3,011
Yep, 1.62 it is.
 
  • #8
chemisttree
Science Advisor
Homework Helper
Gold Member
3,463
501
Welcome back, Borek! You were missed.
 
  • #9
Borek
Mentor
28,562
3,011
Welcome back, Borek! You were missed.
:blushing:

I am planning to spend some time here now ;)
 

Related Threads on Finding pH given molarity and volume problem

  • Last Post
Replies
6
Views
10K
Replies
22
Views
4K
Replies
1
Views
5K
Replies
15
Views
11K
Replies
4
Views
14K
  • Last Post
Replies
1
Views
10K
Replies
1
Views
3K
Replies
2
Views
18K
  • Last Post
Replies
3
Views
3K
Replies
5
Views
7K
Top