Civil Engineering - GATE Exam Questions - Discussion
Discussion Forum : GATE Exam Questions - Section 2 (Q.No. 3)
3.
A wastewater sample contains 10-5.6 mmol/l of OH ions at 25° C. The pH of this sample is
Discussion:
19 comments Page 1 of 2.
Sheela said:
7 years ago
@ Bhanu:
pH is the negative of the base 10 logarithms of the molar concentration, measured in units of moles per liter, of hydrogen ions. To attain standard unit here mmol/L is converted into mol/L.
pH is the negative of the base 10 logarithms of the molar concentration, measured in units of moles per liter, of hydrogen ions. To attain standard unit here mmol/L is converted into mol/L.
Rathi said:
1 decade ago
OH- concentration : 10-5.6 mmol/l = 10-8.6 mol/l.
H+ concentration : 10-14-(-8.6) = 10-5.4 mol/l.
Therefore pH value : 5.4.
H+ concentration : 10-14-(-8.6) = 10-5.4 mol/l.
Therefore pH value : 5.4.
Sarvesh saxsena said:
8 years ago
Ans is D, but you are wrong @Chhaya.
Yes, 1 mol=1000mmol.
So,10^-5.6 mmol=10^(-5.6) 10^(-3) =10^(-8.6).
therfore,POH=8.6 & PH= 14-8.6=5.4.
Yes, 1 mol=1000mmol.
So,10^-5.6 mmol=10^(-5.6) 10^(-3) =10^(-8.6).
therfore,POH=8.6 & PH= 14-8.6=5.4.
Shashank pandit said:
3 years ago
poh = 8.6.
As the mmol will change to mole per lit;
therefore as we know;
pH + pOH = 14.
pH + 8.6 = 14.
pH = 14 - 8.6 = 5.4.
As the mmol will change to mole per lit;
therefore as we know;
pH + pOH = 14.
pH + 8.6 = 14.
pH = 14 - 8.6 = 5.4.
(2)
Ibrahim said:
6 years ago
PH + POH = 14.
Since we are given a concentration of Oh ions we are calculating POH. To get PH we subtract from 14.
Since we are given a concentration of Oh ions we are calculating POH. To get PH we subtract from 14.
Manjula said:
4 years ago
H+ * OH- = 10^-14.
H+ *(10^-5.6 *10^-3) = 10^-14.
H+= (10^-14)/(10^-8.6)
= 10^-5.4.
H+ *(10^-5.6 *10^-3) = 10^-14.
H+= (10^-14)/(10^-8.6)
= 10^-5.4.
(1)
Bhawna said:
8 years ago
D is correct because - 5.6mmol/l convert in mol/l =-8.6.
Then 14 - 8.6 = 5.4.
Then 14 - 8.6 = 5.4.
Chhaya said:
8 years ago
Yes, @Rathi & @Bhawan is right.
1mol= 1000 mmol.
10^-5.6+10^-3=10^-8.6.
1mol= 1000 mmol.
10^-5.6+10^-3=10^-8.6.
Gantela gandhi prasad said:
1 decade ago
Your calculation will be wrong 10^(-8.6) you have to replace 10^(-8.4).
Bharath said:
7 years ago
@Sheela :
pH = -log10^-5.6-3 = -log10^-8.6 = 8.6.
then, 14-8.6 = 5.4.
pH = -log10^-5.6-3 = -log10^-8.6 = 8.6.
then, 14-8.6 = 5.4.
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