HCl Dissolving in Water: Calculating pH and Titration with NaOH

[chawki]

Homework Statement

HCl gas dissolves in water consisting of hydrochloric acid, or hydrochloric acid. HCl dissociates
fully ions as follows: HCl → H⁺ + Cl^-.

Homework Equations

a) Calculate the pH of the solution, which is made ​​by dissolving 1.6 grams of HCl in 0.40 liters of water 298 K temperature.
b) How many ml it takes 0.050 mol/l NaOH solution, when it titraat 30 ml of 0.10 mol/l HCl solution?

The Attempt at a Solution

a)
molar cencentration of H₃O⁺ = n/V
n= 0.0438 mol
C= n/V = 0.0438/0.4 = 0.11 mol/l

PH = -log C of H₃O⁺
PH = -log 0.11
PH = 0.96 (approximately)

b)
HCl with NaOH
Ca*Va = Cb*Vb -------------- we search V of NaOH
Vb = (Ca*Va)/Cb
Vb = (0.10*0.03)/0.050
Vb = 0.06 L
that's 60ml

 

[Borek]

Looks OK.

HCl with NaOH
Ca*Va = Cb*Vb

Beware - you are omitting stoichiometric coefficients. They equal 1 in this case, so the equation holds, but it doesn't hold automatically for every titration.

 

[chawki]

Looks OK.



Beware - you are omitting stoichiometric coefficients. They equal 1 in this case, so the equation holds, but it doesn't hold automatically for every titration.

Thank you Borek
but how would it be if we had 2HCl and 1 NaOH
2 Ca*Va = Cb*Vb ?
also i wonder why they gave us the 298K

 

[Borek]

but how would it be if we had 2HCl and 1 NaOH
2 Ca*Va = Cb*Vb ?

That's not how they react. See

http://www.titrations.info/titration-calculation

also i wonder why they gave us the 298K

My guess is they gave it to make you wonder...