what is the concentration?

Question

dilute hydrochloric acid is titrated with 1.20 mol dm -3 sodium hydroxide solution (NaOH). 20.0 cm3 of the dilute hydrochloric acid (HCl) is require dto neutralise 25.0 cm3 of sodium hydroxide solution.
what is the concentration of the dilute hydrochloric acid in mol dm-3

Answer 1

Okay first, you have to deduce how many moles of acid react with the base.

1 mol HCl ----------> 1 Mol NaOH

1 H+ --------> 1 OH-

Therefore:

Molarity Acid X Volume Acid = Molarity Base X Volume Base

MaVa = MbVb
Ma(20cm3) = 1.2 X 25 cm3
Ma = 30/20
Ma = 1.5 moles per dm-3

That gives the MOLARITY of the acid. The concentration is in grams per dm-3.

1.5 moles of HCl = (Molar Mass) X 1.5
= 36.46 X 1.5
= 54.69g

So effectively;

The Molarity = 1.5 moles dm-3
The Concentration = 54.69 grams per dm-3

Which ever you need!

Answer 2

First write the formula

HCl + NaOH = NaCl + H20
1 : 1 :: 1 : 1
It will be noticed that the molar ratios of reactants & products are all one. Hence;-
Using the equation moles (n) = [conc] x volume used divided by 1000 to convert cm3 to dm3.

Moles (NaOH) = 1.25 x 25 /1000 = Moles (HCl) because the molar ratios are all one.to one

Now we know the moles of HCl used and the volume , hence conc'n of HCl can be calculated.

1.25 x 25/1000 = [conc HCl] x 20/1000 =>
[conc HCl] = 1.25 x25/1000 x 1000/20 =>
[conc HCl] = 1.25 x 25/20 =>
[conc HCl] = 1.25 x 1.25 = 1.5625 mol dm-3 (M)

Answer 3

MaVa=MbVb

Ma(20)=(1.2)(25)
Ma=1.5

Answer 4

Sorry I dont know the answer but, Wow, what a question!!!!!!!!!