Question

strong Acid/ Strong Base Titrations.

can you tell me what is the calculations that I should use for the table below?

Table 1 Vi 0 ml 0 ml 0 ml Trail tti 29.3 ml 4.27 ml 26.2 ml 4.27 ml Trail NaQH (ml NaQHIL) H2S04(moConc. Of acids

Answer 1

I have some doubs in here, cause you are not explaining better what are you actually doing, what did you do first nad what's the first data you obtain for.

However let me help you and give you a guide of how to solve this.

First to all, the KHP has the molecular formula of C₈H₅KO₄  (MW = 204.22 g/mol) This is a commonly used salt to standarize a solution of NaOH (or KOH). So, Is your first data, the data for calibration? if that's the case, the reaction taking place here is the following:

NaOH + C₈H₅KO₄ ----------> C₈H₅O₄^- + H₂O

With this you can see that the relation between one and another is 1:1 so:

moles KHP = moles Base

then:

M1V1 = M2V2.

So, if your first data (first chart) is data to standarize the base, then, you already have the volume of base added, and the volume of KHP which was dissolved. With that, calculate moles of KHP:

moles KHP = 0.5 / 204.22 = 0.0024 moles

And with this calculate, concentration of NaOH:

moles KHP = M2V2.

From there, you already have the volume of base (which I think it's 4.27 mL) convert that to Liter (4.27/1000 = 0.00427 L) and then solve for M2 in the above expression:

0.0024 / 0.00427 = 0.5734 M of NaOH

With this concentration, let's go to chart 2.

In this, you already have the volume of NaOH used (Which would be the Vf from chart 1) and you already have concentration. The reaction is:

2NaOH + H₂SO₄ ---------> Na₂SO₄ + 2H₂O

the ratio of moles are:

moles NaOH/moles H₂SO₄ = 2/1----> which means that: moles NaOH = 2 moles H₂SO₄

then, the above expression of molarity changes as:

M_bV_b = 2M_aV_a

But you need moles so:

M_bV_b = 2moles acid

moles acid = M_bV_b/2

so, to get the moles just replace the values of Vf, and concentration of NaOH obtained, to get the moles of acid. then, calculate concentration of acid:

M_a = moles acid / V_a

V_a will depend of the volume of acid you initially use.

Try to do this and you'll get the final answer.

Hope this helps